JP4252826B2 - Heart treatment equipment - Google Patents

Description

【００４０】
【表２】

【００４１】
【表３】

【００４２】
神経刺激パラメータテーブル記憶手段３１は、表１〜表３に示すような神経刺激のパラメータに関するテーブルを記憶しており、図３のＱＴ時間計時手段３３によって計測されたＱＴ時間に基づいて、神経刺激を行うか否か、行う場合にはそのパラメータを選択、決定して神経刺激制御手段３２に送る。
【００４３】
神経刺激制御手段３２において神経刺激フラグがオンとなった状態で、心房収縮検出手段６が右心房１５の収縮を検出すると、心房収縮検出手段６の出力により、ＯＲ回路２２を経て心房刺激インターバルタイマ２８がリセットされる。心房刺激インターバル設定値記憶手段２９には、正常時における心臓の拍動周期に相当する時間が設定されており、その時間内に次の心房収縮が検出されない場合には、心房刺激インターバルタイマ２８の計数値が心房刺激インターバル設定値記憶手段２９に記憶された設定値に達し、比較手段３０が出力を発する。この比較手段３０の出力により心房刺激が行われるとともに、この比較手段３０の出力はＯＲ回路２２を経て神経刺激制御手段３２に供給される。神経刺激制御手段３２は神経刺激パラメータテーブル記憶手段３１において選定された表１から表３に示すＱＴ時間に応じた各種パラメータの制御に基づいて神経刺激手段７に信号を送り、神経電極リード１６、神経刺激電極１７を経由して迷走神経１８を刺激する。なお、表１から表３に示すパラメータは、単独で用いられるだけでなく、患者の状態に応じていくつかの組み合わせで選択することができることは当然である。
このように、ＱＴ時間によって、患者の運動やメンタルストレスの状態を検出し、運動やメンタルストレスが多い（大きい）ときは、比較的強い神経刺激を行い、少ない（小さい）ときには比較的弱い神経刺激を行う、若しくは神経刺激を行わないように制御する。
【００４４】
図５は、本発明の第1の実施形態の作用を説明するためのフロー図である。
以下、図５のフロー図を用いて、本例の作用を詳細に説明する。まず、神経刺激制御手段３２の神経刺激フラグをオフとする（ステップＳ１）。次に、心室検出継続カウンタ１９をリセットし（ステップＳ２）、更に心房刺激インターバルタイマ２８をリセットして（ステップＳ３）システム全体の初期化を完了させる。
【００４５】
次に、心房収縮検出手段６において心房収縮が検出されたか否かが判断される（ステップＳ４）。判断ステップＳ４で心房収縮が検出されない場合は心房刺激インターバルタイマ２８がタイムアウトしているか否かが判断され（ステップＳ５）、タイムアウトしていると判断されると比較手段３０から心房刺激手段５に出力が発せられ、心房刺激が為される（ステップＳ６）。判断ステップＳ５でタイムアウトされていないと判断された場合は再度心房収縮の検出を待つことになる。判断ステップＳ４において心房収縮が検出されると心房刺激インターバルタイマ２８がリセットし、再び最初から計数を開始する（ステップＳ７）とともに、ＡＶＤタイマ２３の計数をスタートさせる（ステップＳ８）。
【００４６】
次に、神経刺激制御手段３２の神経刺激フラグがオンになっているか否かが判断され（ステップＳ９）、神経刺激フラグがオンになっている場合は神経刺激制御手段３２から神経刺激手段７に信号が発せられ、迷走神経１８の刺激がなされる（ステップＳ１０）。判断ステップＳ９で神経刺激フラグがオフであると判断されると神経刺激を行わないで次のステップに進む。
【００４７】
心室収縮検出手段４が心室の収縮を検出すると、心室検出継続カウンタ１９をインクリメントし、この値が心室検出継続回数設定値記憶手段２０に記憶されている設定値に達したか否か、すなわち、心室検出継続回数設定値記憶手段２０に記憶されている３〜１０回という回数だけ、心室の収縮が連続して検出されたかどうかが判断される（ステップＳ１１）。心室検出継続カウンタ１９の計数値が、上記設定値に達した場合には、心室検出継続回数比較手段２１からＡＶＤ選択手段２６に出力が与えられ、ＡＶＤ選択手段２６は第２ＡＶＤ記憶手段２５に記憶されている設定値を選択する（ステップＳ１２）。第２ＡＶＤ記憶手段２５に記憶されている房室遅延時間の設定値は通常の値より短く設定されているため、心室収縮検出手段４が自発的な心室の収縮を検出する以前にＡＶＤタイマ２３が上記第２ＡＶＤ記憶手段２５の設定値に達するのでＡＶＤ比較手段２７から出力が得られ、強制的な心室刺激が行われるとともに、心室検出継続カウンタ１９がリセットされる（ステップＳ１３）。
【００４８】
判断ステップＳ１１において、心室検出継続カウンタ１９が、心室検出継続回数設定値記憶手段２０に記憶されている設定値に達しないと判断された場合は、心室検出継続回数比較手段２１からＡＶＤ選択手段２６への信号出力は得られないので、ＡＶＤ選択手段２６は第１ＡＶＤ記憶手段２４に記憶されている設定値を選択したままとなる（ステップＳ１４）。
【００４９】
続いて、心室収縮検出手段４において心室収縮が検出されたが否かが判断され（ステップＳ１５）、心室収縮が検出された場合には、心室検出継続カウンタ１９がインクリメントされる（ステップＳ１６）。判断ステップＳ１５で心室収縮が検出されなかったと判断された場合は、ＡＶＤタイマ２３がタイムアウトしているかどうか、すなわちＡＶＤタイマ２３の計数値が、ＡＶＤ選択手段２６が選択している第１ＡＶＤ記憶手段２４又は第２ＡＶＤ記憶手段２５の設定値を越えたか否かが判断される（ステップＳ１７）。
【００５０】
判断ステップＳ１７でＡＶＤタイマ２３がタイムアウトしてないと判断された場合は、再度心室収縮の検出を待つが、ＡＶＤタイマ２３がタイムアウトした場合には、ＡＶＤ比較手段２７から出力が発せられて、心室刺激手段３からの心室刺激が行われるとともに（ステップＳ１８）、心室検出継続カウンタ１９がリセットされ（ステップＳ１９）、更に、ＱＴ時間計時手段３３の計数が開始される（ステップＳ２０）。
【００５１】
この状態で、センサ手段８のＴ波検出手段３４において、Ｔ波部分に相当する、予め定められた期間内で心室内心電図の時間微分を行い、その微分波形からＴ波の負の傾きが最大となる時点を検出し（ステップＳ２１）、ＱＴ時間計時手段３３の計数を停止させる（ステップＳ２２）。Ｔ波微分の負の最大値が検出され、心電図のＱＴ時間が測定されると、その測定した値が神経刺激パラメータテーブル記憶手段３１に送られ、標準値となるＱＴ時間（ＱＴnormal）と比較される。比較の結果、ＱＴ時間が正常範囲内であるかどうかがまず判定され（ステップＳ２３）、正常範囲内であれば、神経刺激のフラグがオフのまま先へ進み、正常範囲外（以下）であれば神経刺激のフラグがオンとされ（ステップＳ２４）、ＱＴ時間測定値に応じて神経刺激の各種パラメータが選択される（ステップＳ２５）。
【００５２】
次に、本発明のセンサ手段８の他の具体例である心電図面積センサを図６に示す。このセンサ手段８は心電図の面積を測定して、ＱＴ時間にかわる患者の生体情報とするものであり、図１の心室刺激手段３への入力、つまりＡＶＤ比較手段２７の出力と心室検出電極１０からの心室内心電図情報が与えられる積分手段３５と、この積分手段の出力から負の最大値を検出する負最大値検出手段３６から構成されている。
【００５３】
積分手段３５は、ＱＴ時間測定と同様に、心室刺激手段３により心室刺激が行われると送られてくる図４Ａに示される心室内心電図の積分を開始する。この積分波形を図４Ｂに示す。図４Ｂから明らかなように、基準となる規定電位Ｑ点からＱＲＳ波（負極性）を積分すると負の面積値が単調に増加していくが、Ｔ波がＱＲＳ波と反対の極性（正）であるため、Ｔ波を積分する段階で、上記負の積分値は減少方向に転換する。心電図面積が負の最大値であるのは、ＱＲＳ波の積分が終了した点ＳからＴ波の検出が始まる時点（仮に「Ｘ」とする。）に至る直線部分の値である。負最大値検出手段３６は、上記の値を検出し、この負の積分最大値を生体情報として、神経刺激パラメータテーブル記憶手段３１に送る。そして、神経刺激パラメータテーブル記憶手段３１において、この負の積分最大値に応じた各種パラメータが選択される。この神経刺激パラメータとしてはＱＴ時間のときと同様に神経刺激パルス列中のパルス数、心房イベントから迷走神経１８を刺激するまでの遅延時間（ディレイ時間）、神経刺激パルスの振幅、神経刺激パルスのパルス幅、神経刺激パルスのパルス間周期、神経刺激パルス列の個数（繰返回数）、神経刺激パルス列間の時間（休止時間）、神経刺激のオン／オフ（神経刺激フラグ）などが考えられる。
【００５４】
次に、図６に示す心電図面積センサを用いたときの心臓治療装置を本発明の第２の実施形態とし、その作用を図７に基づいて説明する。
ステップＳ１〜ステップＳ１９、及びステップＳ２３〜ステップＳ２５は図５と重複するので同一符号で示し、その説明は省略する。
【００５５】
ＡＶＤタイマ２３がタイムアウトして、ＡＶＤ比較手段２７から出力が発せられて、心室刺激手段３からの心室刺激が行われるステップＳ１８の段階から説明を加えることとする。心室刺激がなされると心室検出継続カウンタ１９がリセットされるとともに（ステップＳ１９）、センサ手段８の積分手段３５において心室内心電図情報の積分演算をスタートさせる（ステップＳ２６）。
このとき、心室内心電図は図４Ａに示されるように、基底電位からマイナスに触れているので積分演算結果は負の信号出力として検出される。次に負の最大値が検出されたか否かが判断され（ステップＳ２７）、負の最大値が検出されたと判断された場合には、この負の最大値が正常範囲内であるか否かがまず判定され（ステップＳ２８）、正常範囲内であれば、神経刺激のフラグがオフのまま先へ進み、正常範囲外であれば神経刺激のフラグがオンとされ（ステップＳ２４）、測定された負の最大値に応じて神経刺激の各種パラメータが選択される（ステップＳ２５）。
【００５６】
次に、本発明の心臓治療装置の第３の実施形態を図８のブロック構成図を用いて説明する。図１のブロック構成図と同じ部分は同一符号を付して、説明も簡単にするにとどめる。本発明の第３の実施形態では、制御手段２の構成及びセンサ手段８の構成が、図1と図３、及び図１と図６を結合した本発明の第1及び第２の実施形態と異なっているので、以下、この点を中心に説明する。
【００５７】
図８における本発明の心臓治療装置の第３の実施形態においては、図１に示す第1の実施形態のセンサ手段８に変えて体動センサ４３を備えているところに特徴がある。体動センサ４３には、一般的に、圧電センサや加速度センサが用いられる。センサは、胸部皮下に埋め込まれる心臓治療装置１のハウジング内部に配置され、ハウジングに直接、あるいは回路基板上に取り付けられる。圧電センサでは、物理的運動によって圧電性結晶に応力が加わり、結晶が電気的信号を発生する。加速度センサでは、一般的には片持ち梁を持つ構造となっており、加速度によって梁が運動・変位を生じて電気的信号を発生する。この電気的信号の発生する頻度あるいは強さ、ある一定の周波数内の強さから患者の体動を検出する。激しい運動を行うと体動の変化（加速度や振動）が大きくなり、交感神経も興奮状態となる。したがって、体動センサ４３で、加速度や振動を検出することにより交感神経の興奮度を測定することができる。そして、体動センサ４３からの出力は、体動検出タイマ４４で計測した適当な時間間隔で体動検出手段４５によって検出され、それぞれの計測時における運動量変化が測定される。
【００５８】
図８のブロック構成図において、制御手段２は、心房刺激手段５への入力と心房収縮検出手段６の出力が供給されるＯＲ回路２２と、ＯＲ回路２２の出力が供給され計数を開始する房室遅延タイマ４０（図１のＡＶＤタイマ２３と同じ）と、正常時の房室遅延時間を設定値として記憶する房室遅延設定値記憶手段４１と、房室遅延タイマ４０で計数した時間が房室遅延設定値記憶手段４１に記憶されている設定値と一致したことを検出する房室遅延比較手段４２と、ＯＲ回路２２の出力が供給される心房刺激インターバルタイマ２８と、心房刺激インターバル設定値記憶手段２９と、心房刺激インターバルタイマ２８の計数値が心房刺激インターバル設定値記憶手段２９に記憶されている設定値に一致したときに出力を発する比較手段３０と、体動センサ４３からの出力を体動検出タイマ４４で計測した適当な時間ごとに検出する体動検出手段４５からの出力が供給される神経刺激パラメータテーブル記憶手段３１と、ＯＲ回路２２の出力が供給され、神経刺激のタイミングを制御する神経刺激制御手段３２から構成されている。
【００５９】
以下、本発明の心臓治療装置の第３の実施形態の作用を説明する。
図８において、心房収縮検出手段６が右心房１５の収縮を検出すると、心房収縮検出手段６は、その出力をＯＲ回路２２を介して心房刺激インターバルタイマ２８と房室遅延タイマ４０に送り、心房刺激インターバルタイマ２８をリセットするとともに、房室遅延タイマ４０の計数をスタートさせる。
【００６０】
房室遅延設定値記憶手段４１には、心房が収縮してから心室が収縮するまでの患者にとって許容される遅延時間が設定されており、通常は、この設定値をカウントする前に、自発的な心室収縮が起こり、房室遅延タイマ４０はその度毎に、心室収縮検出手段４の出力によりリセットされる。このため、房室遅延タイマ４０は、房室遅延設定値記憶手段４１に記憶された設定値までカウントしないので、房室遅延比較手段４２からの出力は得られず、心室刺激手段３には房室遅延比較手段４２の出力が供給されない。したがって、強制的な心室刺激は行われない。
【００６１】
房室遅延設定値記憶手段４１に記憶されている房室遅延時間以内に自発的な心室収縮が起こらない場合は、心室収縮検出手段４から出力が得られないので、房室遅延タイマ４０は停止することなくカウントを継続する。すなわち、房室遅延タイマ４０は、房室遅延設定値記憶手段４１に記憶されている設定値に一致するまでカウントを継続し、一致した時点で房室遅延比較手段４２から出力を発生する。この房室遅延比較手段４２の出力は、心室刺激手段３に送られ、心室電極リード９を経て心室刺激電極１０により、右心室１４の刺激を行う。
【００６２】
一方、心房収縮検出手段６が右心房１５の収縮を検出すると、心房収縮検出手段６の出力により、ＯＲ回路２２を経て心房刺激インターバルタイマ２８がリセットされる。心房刺激インターバル設定値記憶手段２９には、正常時における心臓の拍動周期に相当する時間が設定されており、その時間内に次の心房収縮が検出されない場合には、心房刺激インターバルタイマ２８の計数値が心房刺激インターバル設定値記憶手段２９に記憶された設定値に達し、比較手段３０が出力を発する。この比較手段３０の出力により心房刺激が行われるとともに、この比較手段３０の出力はＯＲ回路２２を経て神経刺激制御手段３２に供給され、神経刺激手段７により迷走神経１８の刺激が行われる。ここで、神経刺激の頻度や強度については、患者の状態に応じて、神経刺激パラメータテーブル記憶手段３１に記憶されているパラメータを選択することにより調整される。このパラメータの選択は、加速度センサに代表される体動センサ４３の出力を体動検出手段４５で検出することにより行われる。
【００６３】
次に、本発明の心臓治療装置の第４の実施形態を図９のブロック構成図を用いて説明する。図８のブロック図と同じものは同一符号を付している。
この第４の実施形態が第３の実施形態と異なるところは、神経刺激パラメータテーブル記憶手段３１のパラメータを選定するセンサ部分のみである。第４の実施形態においては、心房電極あるいは心室電極のいずれかに設けられる血液センサ４６が用いられる。この血液センサ４６で検出される生体情報には、中心静脈血液温度、静脈血酸素飽和度、血液ｐＨ、血液中カテコラミン量などがあるが、これらはいずれも運動やストレスによる自律神経（特に交感神経）の興奮度と関係するものである。
【００６４】
以下、本発明の心臓治療装置の第４の実施形態の作用を説明するが、ブロック構成図全体の概要説明は図８に示した第３の実施形態と同じなので省略する。この第４の実施形態においては、右心室１４内に設けた心室刺激／検出電極１０あるいは心室電極リード９中に取り付けた血液センサ４６が用いられる。図９においては、わかりやすく図示するため、心室刺激／検出電極１０あるいは心室電極リード９とは別体のように描いているが、心臓１３内においては一体的に形成されるものである。
【００６５】
この右心室１４内に配置された血液センサ４６により、交感神経の興奮度と関係する上述した血液中のさまざまな生体情報が検出され、この検出情報が神経刺激パラメータテーブル記憶手段３１に送られて、迷走神経１８の刺激の頻度や強度を制御するパラメータの選択が行われる。
【００６６】
次に、図１０に示すブロック構成図に基づいて、本発明の第５の実施形態を説明する。図１０の実施形態においても、図８及び図９に示すものと同一部分のブロックは同一符号を付している。この第５の実施形態において、第３及び第４の実施形態と異なるところは、神経刺激パラメータテーブル記憶手段３１のパラメータを選択するための生体情報を検出する呼吸センサ５０を設けた点である。この呼吸センサ５０は、心房電極リード１１に接続されるインピーダンス計測手段５１と、このインピーダンス計測手段の出力が加えられる呼吸検出手段５２と、呼吸検出のタイミングを計る呼吸検出タイマ５３とから構成される。インピーダンス計測手段５１は、心房電極リード１１を介して、胸部皮下に埋め込まれる心臓治療装置１のチタン製ハウジングと心房刺激／検出電極１２との間に心臓が刺激されない強度の定電流の計測波形を重畳・印加し、その両端の電圧を測ることによってインピーダンスを計測する。これにより呼吸センサ５０は、右心房１５と胸部との間のインピーダンスの変化から胸郭の拡張や収縮状態が検出できるため、患者の呼吸状態を知ることができる。なお、呼吸センサ５０は、インピーダンス計測手段５１と心室電極リード９を接続して、右心室１４と胸部との間のインピーダンスの変化から患者の呼吸状態を知る構成とすることもできる。
【００６７】
以下、本発明の心臓治療装置の上記第５の実施形態の作用を説明する。運動やストレスにより交感神経の興奮度が高まると、呼吸（呼吸数や呼吸量）が激しくなり、それが心房電極リード１１を介して、呼吸センサ５０のインピーダンス計測手段５１でインピーダンス変化として捉えられる。呼吸検出手段５２は呼吸検出タイマ５３でカウントされる適当な時間ごとに、インピーダンス計測手段５１で計測されるインピーダンス波形を処理し、インピーダンス変化の速度からは呼吸数が、大きさからは呼吸量が検出され、この呼吸数や呼吸量に応じて、神経刺激パラメータテーブル記憶手段３１のパラメータを選択する。そして、この選択されたパラメータに基づいて、神経刺激制御手段３２から神経刺激手段７に信号が発せられ、神経刺激手段７により、患者の状態に応じて適切な迷走神経１８の刺激が行われる。
【００６８】
図８〜図１０に示す本発明の心臓治療装置の第３〜第５の実施形態について、図１１のフロー図に基づいてまとめてその動作を説明する。この３つの実施形態の異なる部分はセンサ手段の部分であるから、以下の説明ではこれらを全て生体情報検出センサとして説明する。この生体情報検出センサは各実施形態に応じて、それぞれ体動センサ、血液センサ、呼吸センサを表している。
まず、最初に、神経刺激制御手段３２の神経刺激フラグをオフにするとともに（ステップＳ３０）、生体情報センサに含まれる生体情報検出タイマをスタートさせ（ステップＳ３１）、あわせて、心房刺激インターバルタイマ２８をリセットし、計数を開始させる（ステップＳ３２）。
【００６９】
次に、生体情報検出センサの生体情報検出タイマがタイムアウトしているか否かが判断される（ステップＳ３３）。生体情報検出タイマがタイムアウトしている場合、生体情報を検出する時間になると、生体情報が検出され（ステップＳ３４）、再び生体情報検出タイマがリセットされる（ステップＳ３５）。そして、続いて、生体情報検出センサにおける生体情報の検出に基づいて、神経刺激パラメータテーブル記憶手段３１のテーブルからその患者に最適な神経刺激パラメータが選択される（ステップＳ３６）。ここでの神経刺激パラメータの選択には、神経刺激を行うか否かの選択も含まれ、神経刺激を行う場合には神経刺激フラグがオンされる。判断ステップＳ３３で生体情報検出タイマがタイムアウトしていないと判断されると、生体情報の検出はなされずに、心房収縮の検出を待つ。
【００７０】
続いて、心房収縮検出手段６において、心房収縮が検出されたか否かが判断される（ステップＳ３７）。心房収縮が検出された場合には、心房刺激インターバルタイマ２８をリセットし（ステップＳ３８）、続いて房室遅延タイマ４０をリセットして計数を開始させる（ステップＳ３９）。次に、神経刺激制御手段３２の神経刺激フラグがオンになっているか否かが判断され（ステップＳ４０）、神経刺激フラグがオンになっている場合は神経刺激制御手段３２から神経刺激手段７に信号が発せられ、迷走神経１８の刺激がなされる（ステップＳ４１）。判断ステップＳ４０で神経刺激フラグがオフであると、神経刺激を行わないで次のステップに進む。
【００７１】
判断ステップＳ３７で心房収縮が検出されなかったと判断された場合は、心房刺激インターバルタイマ２８がタイムアウトしているかどうか、すなわち心房刺激インターバルタイマ２８の計時時間が心房刺激インターバル設定値記憶手段２９に記憶されている設定値を超えたかどうかが判断される（ステップＳ４２）。そして、タイムアウトしていると判断されると、比較手段３０から心房刺激手段５に出力が発せられ、心房刺激が行われる（ステップＳ４３）。
【００７２】
ステップＳ４１において、迷走神経１８の刺激が為された後は、再び生体情報検出タイマがタイムアウトしているか否かが判断される（ステップＳ４４）。そして、タイムアウトしていると判断された場合には、ステップＳ３４〜ステップＳ３６と同様に、生体情報検出（ステップＳ４５）、生体情報検出タイマリセット（ステップＳ４６）、神経刺激パラメータ設定（ステップＳ４７）が順次行われ、次の心室収縮の検出ステップ（ステップＳ４８）に入る。なお、ここでの神経刺激パラメータの選択には、神経刺激を行うか否かの選択も含まれ、神経刺激を行う場合には神経刺激フラグがオンされる。
判断ステップＳ４４で生体情報検出タイマがタイムアウトしていないと判断されると、つまり、未だ計測するタイミングではないと判断されると、同様に、次の心室収縮検出ステップ（ステップＳ４８）に入る。
【００７３】
次に、判断ステップＳ４８で、心室の収縮が検出されると、房室遅延タイマ４０が計数を停止し（ステップＳ４９）、再び判断ステップＳ３３に戻る。判断ステップＳ４８で、心室収縮が検出されなかったときは、房室遅延タイマ４０がタイムアウトしているかどうか、すなわち、房室遅延設定値記憶手段４１に記憶されている設定値を超えたかどうかが判断される（ステップＳ５０）。判断ステップＳ５０でタイムアウトしていると判断されると、房室遅延比較手段４２から心室刺激手段３に出力を発し、心室刺激が行われる（ステップＳ５１）。この心室刺激が行われた後は、再び判断ステップＳ３３に戻り、判断ステップＳ５０で房室遅延タイマ４０がタイムアウトしていないと判断されると、判断ステップＳ４４に戻り、再び生体情報検出タイマのタイムアウトが為されたか否かの判断を行う。
【００７４】
図１２は、本発明の心臓治療装置の第６の実施形態を示すブロック構成図である。図８〜図１０に示す第３〜第５の実施形態と異なるところは、生体情報の種類として心室内圧力の時間変化率（時間微分）dp/dtを検出している部分である。同一の構成部分は同一符号を付している。
この本発明の第６の実施形態を示す図１２においては、右心室１４内に設けられる圧力センサ６０と、圧力センサ６０の出力を受け取る心室収縮性心室圧力センサ６１と、心室収縮検出手段４の出力と房室遅延比較手段４２の出力、すなわち心室刺激を命じる情報が供給され、その出力を心室収縮性心室圧力センサ６１に供給するＯＲ回路６２が新たに付加されている。そして、心室収縮性心室圧力センサ６１は、圧力センサ６０からの信号入力を時間微分する微分回路６３と、ＯＲ回路６２の出力のタイミングで微分回路６３の出力をモニタし、その最大値を保持する最大値保持回路６４から構成される。
【００７５】
以下、本発明の第６の実施形態の作用について説明する。圧力センサ６０は、心室が収縮するときの圧力を測定するものであり、通常は心室刺激／検出電極１０、あるいは心室電極リード９中に装備されている。そして、この圧力センサ６０により心室内圧力を計測し、この圧力センサ６０からの信号を微分回路６３で微分したものがdp/dtであり、最大値保持回路６４において保持された微分最大値がmax dp/dt である。この微分最大値max dp/dtは、ＯＲ回路６２の出力のタイミング、すなわち、心室収縮の検出もしくは心室への刺激のタイミングから所定の期間内、例えば100msの期間内の最大値が保持されるようにしている。そして保持されたmax dp/dtは、制御手段２の神経刺激パラメータテーブル記憶手段３１に送られ、この値に応じてその患者にとって最適な刺激パラメータが選択される。
【００７６】
ここで、心室のmax dp/dtは、激しい運動やメンタルストレスによって増加するので、このmax dp/dtの値から、運動やメンタルストレスの大小を感知することができる。この性質を利用して、max dp/dtが大きいときは、強い神経刺激を行い、max dp/dtが小さいときは、弱い神経刺激にとどめるか、神経刺激を行わないようにする。
【００７７】
図１３は、本発明の心臓治療装置の第７の実施形態を示すブロック構成図である。図１２に示す第６の実施形態と異なるところは、生体情報の種類とその検出センサの部分である。第６の実施形態では、生体情報として心室内圧力の時間変化率（時間微分）dp/dtの最大値を用いたのであるが、図１３に示す第７の実施形態では、心室収縮性インピーダンスセンサ７０を用いている。それ以外のブロック構成は第６の実施形態とまったく同じであるので、同一のブロック構成は同一符号を付している。
【００７８】
心室収縮性インピーダンスセンサ７０の具体例を図１４と図１５に示す。図１４は心室前駆出時間センサ７１の例であり、図１５は一回拍出量センサ７５の例である。
図１３の心室収縮性インピーダンスセンサ７０として図１４の心室前駆出時間センサ７１を用いたものを本発明の第７の実施形態として以下に説明する。
心室前駆出時間とは、電気的な心室収縮（心室の収縮検出あるいは心室刺激）の開始から実際に心室が血液の駆出を開始するまでの時間である。この心室前駆出時間から、運動やメンタルストレスの多少を感知することができる。
【００７９】
この心室前駆出時間センサ７１は、心室収縮検出あるいは心室刺激をトリガーとして時間の計測を開始する前駆出時間計時手段７２と、心室の容積変化をモニターするインピーダンス計測手段７３と、インピーダンス計測手段７３の出力を受けて心室容積に所定の減少があったときに血液の駆出が始まったと判断する心室駆出検出手段７４から構成される。
【００８０】
以下、第７の実施形態の作用を説明すると、図１３において、心室収縮検出手段４の出力と房室遅延比較手段４２の出力はＯＲ回路６２に供給される。したがって、ＯＲ回路６２には、心室の収縮を検出した場合若しくは心室刺激を行った場合に出力が得られ、この出力が心室前駆出時間センサ７１（図１４）の前駆出時間計時手段７２に供給され、前駆出時間の計測が開始される。そして、心室刺激／検出電極１０は心室電極リード９を介して図１４のインピーダンス計測手段７３に接続されており、インピーダンス計測手段７３は、心室の容積に変動があるとインピーダンスの変化として、その心室の容積変動を検出する。
【００８１】
インピーダンス計測手段７３の出力は、心室駆出検出手段７４に送られ、心室駆出検出手段７４は、インピーダンス計測手段７３からの出力、すなわちインピーダンス変化をモニターして、心室容積に所定の減少があった場合に血液の駆出を開始したと判断し、前駆出時間計時手段７２の計時を停止させる。この計測された心室前駆出時間は、図１３の神経刺激パラメータテーブル記憶手段３１に送られ、心室前駆出時間に応じて患者に最適な神経刺激のためのパラメータが選択される。この前駆出時間は運動やメンタルストレスによって短縮するので、心室前駆出時間が小さいときは迷走神経の刺激を強くするようにする。
【００８２】
図１５は、図１３の心室収縮性インピーダンスセンサ７０の一例を示す一回拍出量センサ７５の構成を示すブロック図である。
一回拍出量とは、一回の心室収縮において、拡張終期心室容積から収縮終期心室容積を減じた量であり、この一回拍出量からも運動やメンタルストレスの大小を知ることができるものである。
図１５の一回拍出量センサ７５を図１３の心室収縮性インピーダンスセンサ７０として採用した例を本発明の第８の実施形態として以下に説明する。
【００８３】
図１５に示す一回拍出量センサ７５は、心室収縮検出あるいは心室刺激をトリガーとして心室の拡張終期の容積を検出する拡張終期容積検出手段７６と、インピーダンス変化により心室の容積変化をモニターするインピーダンス計測手段７７と、拡張終期容積検出に続いてインピーダンス計測手段７７の出力から心室容積の最小値を収縮終期容積として検出する収縮終期容積検出手段７８と、拡張終期容積検出手段７６の出力から、収縮終期容積検出手段７８の出力を減算して心室の一回拍出量を演算する一回拍出量演算手段７９から構成される。
【００８４】
以下、本発明の第８の実施形態の作用を説明すると、図１３において、上述のように、ＯＲ回路６２には、心室の収縮を検出した場合若しくは心室刺激を行った場合に出力が得られ、この出力が一回拍出量センサ７５（図１５）の拡張終期容積検出手段７６に供給される。一方、心室刺激／収縮電極１０に接続されているインピーダンス計測手段７７は、計測したインピーダンスから心室の容積を割り出し、これを拡張終期容積検出手段７６と収縮終期容積検出手段７８に送る。拡張終期容積検出手段７６は、インピーダンス計測手段７７からの出力に基づいて心室収縮検出時あるいは心室刺激時の心室容積を検出してこの容積を心室拡張終期容積とする。また、収縮終期容積検出手段７８は、インピーダンス計測手段７７の出力をモニタし、心室容積の最小値を心室収縮終期容積として検出する。
【００８５】
そして、一回拍出量演算手段７９において、拡張終期容積検出手段７６と収縮終期容積検出手段７８との出力差、すなわち拡張終期心室容積と収縮終期心室容積との差が演算され、この演算結果が一回拍出量として図１３の神経刺激パラメータテーブル記憶手段３１に送られる。そして、一回拍出量に応じて患者に最適な神経刺激のためのパラメータが選択される。この一回拍出量は運動やメンタルストレスによって多くなったり少なくなったりするので、一回拍出量が多いときは、迷走神経の刺激を強くするようにする。
【００８６】
次に、図１６のフロー図を用いて、図１２〜図１５に示す本発明の第６〜第８の実施形態の作用を詳細に説明する。
まず、最初に、神経刺激制御手段３２の神経刺激フラグをオフとし（ステップＳ６０）、あわせて、心房刺激インターバルタイマ２８がリセットされ、計数が開始する（ステップＳ６１）。
【００８７】
この状態で初期設定が完了し、次に、心房収縮検出手段６において、心房収縮が検出されたか否かが判断される（ステップＳ６２）。心房収縮が検出された場合には、心房刺激インターバルタイマ２８をリセットし（ステップＳ６３）、続いて房室遅延タイマ４０をリセットして計数を開始させる（ステップＳ６４）。次に、神経刺激制御手段３２の神経刺激フラグがオンになっているか否かが判断され（ステップＳ６５）、神経刺激フラグがオンになっている場合は神経刺激制御手段３２から神経刺激手段７に信号が発せられ、迷走神経１８の刺激がなされる（ステップＳ６６）。判断ステップＳ６５で神経刺激フラグがオフであると、神経刺激を行わないで次のステップに進む。
【００８８】
判断ステップＳ６２で心房収縮が検出されなかったと判断された場合は、心房刺激インターバルタイマ２８がタイムアウトしているかどうか、すなわち心房刺激インターバルタイマ２８の計時時間が心房刺激インターバル設定値記憶手段２９に記憶されている設定値を超えたかどうかが判断される（ステップＳ６７）。そして、タイムアウトしていると判断されると、比較手段３０から心房刺激手段５に出力が発せられ、心房刺激が行われる（ステップＳ６８）。
【００８９】
続いて、心室の収縮がなされたか否かが判断される（ステップＳ６９）。そして、心室の収縮が検出されると、房室遅延タイマ４０の計数を停止させる（ステップＳ７０）。判断ステップＳ６９で、心室収縮が検出されなかったときは、房室遅延タイマ４０がタイムアウトしているかどうか、すなわち、房室遅延設定値記憶手段４１に記憶されている設定値を超えたかどうかが判断される（ステップＳ７１）。判断ステップＳ７１でタイムアウトしていると判断されると、房室遅延比較手段４２から心室刺激手段３に出力を発し、心室刺激が行われる（ステップＳ７２）。この心室刺激が行われたとき、及びステップＳ７０で房室遅延タイマ４０の計時を停止させた後、各実施形態のセンサ手段によって、心室圧力（第６の実施形態）、前駆出時間（第７の実施形態）及び一回拍出量（第８の実施形態）の検出が行われる（ステップＳ７３）。そして、この各実施形態のセンサ手段により検出した、運動やメンタルストレスに関連した生理量が神経刺激パラメータテーブル記憶手段３１に送られ、患者に応じた最適な神経刺激パラメータが選択される（ステップＳ７４）。ここでの神経刺激パラメータの選択には、神経刺激を行うか否かの選択も含まれ、神経刺激を行う場合には神経刺激フラグがオンされる。
【００９０】
以上、本発明の心臓治療装置について、複数の実施の形態についてブロック図、フロー図に基づいて説明したが、本発明は、これらの実施の形態にとどまらず、交感神経の興奮度を示すさまざまな生体情報を検出し、神経刺激パラメータを制御することが可能である。
【００９１】
【発明の効果】
以上述べたように、本発明によれば、運動やストレスによる患者の交感神経の興奮度をさまざまな生体情報によって知り、その興奮度に応じて適切できめ細かに迷走神経の刺激を行うことができるため、神経刺激による副作用や心拍数が低下しすぎることの回避、消費電力節約等の甚大な効果が得られる。
【図面の簡単な説明】
【図１】本発明の心臓治療装置の第1及び第２の実施形態の構成例を示すブロック図である。
【図２】本発明の心臓治療装置に用いられる電極リード及び刺激電極の心臓への配置図である。
【図３】本発明心臓治療装置の第１の実施形態におけるＱＴ時間を検出するためのセンサ手段の構成図である。
【図４】Ａは心臓の心室内心電図とＱＴ時間を示す波形図、Ｂはこの心室内心電図を積分した波形図である。
【図５】図１のブロック図のセンサ手段としてＱＴ時間検出センサを用いた本発明の心臓治療装置の第１の実施形態の作用を示すフロー図である。
【図６】本発明の心臓治療装置の第２の実施形態に用いられる心電図面積を検出するための心電図面積センサの構成図である。
【図７】図１のブロック図のセンサ手段として心電図面積センサを用いた本発明の心臓治療装置の第２の実施形態の作用を示すフロー図である。
【図８】本発明の心臓治療装置の第３の実施形態の構成例を示すブロック図である。
【図９】本発明の心臓治療装置の第４の実施形態の構成例を示すブロック図である。
【図１０】本発明の心臓治療装置の第５の実施形態の構成例を示すブロック図である。
【図１１】図８〜図１０に示す本発明の心臓治療装置の第３〜第５の実施形態の作用を示すフロー図である。
【図１２】本発明の心臓治療装置の第６の実施形態の構成例を示すブロック図である。
【図１３】本発明の心臓治療装置の第７〜第８の実施形態に共通の構成例を示すブロック図である。
【図１４】本発明の心臓治療装置の第７の実施形態に用いられる心室前駆出時間センサの構成図である。
【図１５】本発明の心臓治療装置の第８の実施形態に用いられる一回拍出量センサの構成図である。
【図１６】図１２〜図１５に示す本発明の心臓治療装置の第６〜第８の実施形態の作用を説明するためのフロー図である。
【図１７】Ａは心臓の構造を示す図であり、Ｂは体表面に電極を置いて測定した心電図の例である。
【図１８】神経刺激パラメータを説明する図である。
【符号の説明】
１・・・心臓治療装置、２・・・制御手段、３・・・心室刺激手段、４・・・心室収縮検出手段、５・・・心房刺激手段、６・・・心房収縮検出手段、７・・・神経刺激手段、８・・・センサ手段、９・・・心室電極リード、１０・・・心室刺激／検出電極、１１・・・心房電極リード、１２・・・心房刺激／検出電極、１３・・・心臓、１６・・・神経電極リード、１７・・・神経刺激電極、１８・・・迷走神経、４３・・・体動センサ、４４・・・血液センサ、５０・・・呼吸センサ、６１・・・心室収縮性心室圧力センサ、７１・・・心室前駆出センサ、７５・・・一回拍出量センサ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cardiac treatment device for preventing sudden cardiac death due to fatal arrhythmia caused by stress or exercise.
[0002]
[Prior art]
FIGS. 17A and 17B show the structure of the heart and the electrocardiogram waveform. The heart is composed of two atriums and two ventricles. The atrium is a room for accumulating returned blood, and the ventricle is a room for delivering blood. Blood from the vena cava enters the right atrium and is sent from the right atrium through the right ventricle to the pulmonary artery. Arterial blood that has taken up oxygen in the lungs enters the left atrium via the pulmonary veins, and is sent from the left atrium through the left ventricle to the aorta. The ventricle is thicker than the atria, and there are valves between the right and right ventricles, the right and left ventricles, the left and left ventricles, and the left and right ventricles to prevent blood regurgitation. Is provided. Heart failure is a condition in which the function of the ventricle that pumps blood is deteriorated, and many are left heart failure in which the condition of the left ventricle is deteriorated.
[0003]
The heart beats about 100,000 times a day although there are individual differences. Since a weak current is generated every beat, the state of the heart can be known by detecting this current. An electrocardiogram shown in FIG. 17B shows a temporal change in the state of the heart. This electrocardiogram is for a normal examination in which an electrode is attached to the body surface and is basically composed of a plurality of waves having an amplitude of several millivolts. As shown in the figure, first, the first wave is a P wave, which represents the current when the atria (right and left atria) contract. The next big wave called QRS wave appears when the ventricle contracts and pushes blood to the whole body. In the right ventricle, venous blood is sent to the pulmonary artery, and in the left ventricle, arterial blood is sent to the aorta. The T wave is an electric current when the contracted ventricular muscle is electrically restored, and this series of wave transitions is an electrical view of the process from the contraction of the heart muscle to the relaxation. .
The interval from when the atrium contracts to when the ventricle contracts is called the PQ interval, and the time from when the ventricle contracts to when the ventricle relaxes is called the QT interval or QT time.
[0004]
Sudden deaths, especially those caused by heart disease, are called sudden cardiac deaths, and about 50,000 people a year in Japan. The direct cause of sudden cardiac death is the occurrence of ventricular tachycardia or ventricular fibrillation, which is called fatal arrhythmia, causing hemodynamic failure. In ventricular tachycardia, the ventricle pulsates abnormally and rapidly, and in ventricular fibrillation, the individual muscle fibers that make up the ventricle begin to be disorderly excited and the entire ventricle trembles in small increments. When a fatal arrhythmia occurs, the heart's pumping function declines or disappears, making it impossible to pump out the necessary blood throughout the body, resulting in loss of consciousness associated with a decrease in cerebral blood flow. It can lead to death.
[0005]
Treatment for implanting an implantable cardioverter defibrillator (ICD) is performed for a patient who has such a risk of sudden cardiac death. When detecting the occurrence of ventricular tachycardia or ventricular fibrillation, the ICD performs defibrillation by applying an electric shock to the heart. However, the ICD is a therapeutic treatment device that operates after an abnormality occurs in the heart, and a large electric shock for defibrillation may damage the heart tissue.
[0006]
By the way, although the cardiac activity is controlled by the autonomic nervous system, the autonomic nervous system includes the sympathetic nervous system and the parasympathetic nervous system, and the parasympathetic nervous system of the heart is the vagus nerve. When sympathetic activity increases (tense), cardiac activity (heart rate and cardiac output) increases, and when vagal activity increases, cardiac activity (heart rate) decreases. Activity in the sympathetic and vagus nerves is usually antagonistic and the heart is stably controlled to maintain an appropriate resting heart rate, approximately 70 beats / minute. That is, when the sympathetic nerve is tensioned, it acts on the heart in an exciting manner, whereas when the vagus nerve is tensioned, it acts on the heart in a suppressive manner.
[0007]
Recently, it has been proposed to treat ventricular arrhythmia by performing electrical stimulation of the vagus nerve using such an action (see, for example, Patent Document 1). In this proposal, when a tachyarrhythmia is detected, an activation current from a current generator for nerve stimulation is sent to the vagus nerve, and fibrillation of the heart is removed (defibrillation is performed).
[0008]
An apparatus that detects arrhythmia in response to the activity of a nerve signal that transmits information from the autonomic nervous system to the heart has also been proposed (see, for example, Patent Document 2). This arrhythmia detection device has a sensor for detecting neural activity and a comparator having a threshold value that forms a condition for the presence of arrhythmia. This comparator uses an output signal indicating the occurrence of arrhythmia as a condition of neural activity. Output depending on whether or not they match. That is, as soon as chronic fibrillation or other dangerous tachyarrhythmia is detected from changes in autonomic nervous system activity, the vagus nerve is lightly activated for 5 seconds. When the return to the normal state is detected, the treatment is terminated, but when the abnormal state of the heart is continuously detected, the treatment is continued, and if sympathetic block is advantageous, the stellate ganglion is used. Done for a few seconds. When the heart activity falls below a predetermined rate due to the current being supplied to the vagus and sympathetic nerves, the pacemaker block automatically initiates stimulation to the heart, thereby attempting to maintain or repair a normal heartbeat It is.
[0009]
Furthermore, in order to prevent a fatal arrhythmia, a method and apparatus for applying electrical stimulation to the vagus nerve has been proposed (see, for example, Patent Document 3). The device for treating cardiac arrhythmia is intended to prevent or stop cardiac arrhythmia and maintain an appropriate function of the heart through stimulation of cardiac tissue and stimulation of the vagus nerve. This heart treatment device not only compares the preset tachycardia detection interval threshold to the patient's beat, but also changes in the ST portion (voltage) of the electrocardiogram suggesting acute myocardial ischemia and complicated ventricles Other factors related to the tachycardia are also investigated, and it is possible to suppress the tachycardia by stimulating the vagus nerve based on this. In addition, the vagus nerve is stimulated in order to overcome the heart rate decrease accompanying the stimulation to the vagus nerve, and the heart is stimulated so that the heart rate of the patient falls within an allowable range. This cardiac arrhythmia treatment device comprises means for continuously measuring an electrocardiogram of a patient's heart, means for detecting a feature indicative of tachycardia of the electrocardiogram, means for initializing memory of a series of characteristics, one or more electric And a means for initializing a series of characteristics of the electrocardiogram following the supply of the stimulating action.
[0010]
[Patent Document 1]
JP-A-8-38625
[Patent Document 2]
JP-A-8-52121
[Patent Document 3]
WO93 / 21824 (PCT / US93 / 00051)
[0011]
[Problems to be solved by the invention]
Excessive stimulation of the vagus nerve affects organs other than the heart, such as indigestion and nausea due to excessive secretion of gastric acid, insulin, glucagon, etc., or increased cough, pharyngitis, laryngospasm, sensory paralysis, respiratory distress However, there is a problem that side effects such as induction of asthma attacks become prominent in patients with a history of asthma, and conversely there is a problem that sufficient effects cannot be obtained if the stimulation to the vagus nerve is weak.
However, although the thing of patent document 1 gives activation current to a vagus nerve and prevents tachyarrhythmia, in order to perform uniform nerve stimulation irrespective of a patient's condition, it solves the above-mentioned problem Can not do it.
Moreover, the thing of patent document 2 arrange | positions the sensor body for detecting an arrhythmia in at least one of the vagus nerve or sympathetic nerve in the cervical region outside the heart, and this sensor body is directly connected to the nerve. Detects arrhythmia by touching or detecting nerve activity through blood vessels, thereby detecting chronic fibrillation or other dangerous tachyarrhythmias due to changes in autonomic nervous system activity It can be done. However, since this device also performs uniform nerve stimulation, side effects may occur and sufficient effects may not be obtained. Further, since the nerve activity signal is weak, when the sensor is placed in the cervical region, there is a possibility that an electromyogram of the peripheral skeletal muscle accompanying the movement of the cervical region or an external noise is erroneously detected. In particular, when the sensor is placed in a blood vessel, the blood vessel wall between the sensor body and the nerve, further connective tissue, fat, etc. intervene to increase the distance between the two, and the detected nerve activity signal is weaker. Thus, there is a possibility that discrimination from noise becomes difficult. Furthermore, it has been difficult to find the location of the sensor body in the blood vessel where the sensitivity to the nerve activity signal is optimal and to fix it stably at that location.
[0012]
The method described in Patent Document 3 detects an ST value (voltage) from electrocardiogram information, generates a nerve stimulation trigger based on whether the value exceeds a threshold, and prevents tachycardia and fibrillation in advance. It is an object. However, like the ones described in Patent Documents 1 and 2, it merely performs uniform nerve stimulation, and fine nerve stimulation cannot be performed.
The ST value indicates the degree of myocardial ischemia or myocardial injury, and further changes in the acute phase of ischemia but returns to the normal level in the chronic phase. In the control of nerve stimulation based on the value, it is difficult to realize prevention under various situations experienced in daily life.
[0013]
Fatal arrhythmias occur frequently in patients with organic heart diseases such as myocardial infarction and cardiomyopathy. It is known that autonomic excitation, particularly enhancement of sympathetic tone, is strongly involved in the development of this lethal arrhythmia. This increase in sympathetic nerve tone increases the automatic ability of the myocardium and the stimulation conduction system, shortens the refractory period of excitement, and makes arrhythmia easy to occur. On the other hand, reports of sudden cardiac death in cases of attenuation of vagus nerve excitation and loss of circadian fluctuation in patients with organic heart disease also suggest the involvement of increased sympathetic tone. In general, sympathetic tone is increased by exercise and mental stress. Especially in patients with organic heart disease, the combination of organic lesions of the heart and increased sympathetic tone increases the possibility of the occurrence of fatal arrhythmias.
[0014]
Thus, the present invention detects fatal arrhythmia by indirectly detecting sympathetic nerve tension by detecting biological information that changes due to exercise, mental stress, etc., and controlling stimulation of the vagus nerve. If the sympathetic excitement is judged to be intense from the detected exercise or mental stress, the strong nerve stimulation is applied, and the sympathetic excitement from the exercise or mental stress is provided. When it is determined that the value is small, fine nerve stimulation is realized by performing control so that weak nerve stimulation is performed.
[0015]
The present invention also provides a heart for preventing the occurrence of a lethal arrhythmia by detecting exercise, mental stress, etc. by any one of ventricular contractility, body movement, respiration, and blood sensors and controlling stimulation of the vagus nerve. For the purpose of providing a therapeutic apparatus, control is performed so that vagus nerve stimulation is performed when detected exercise, mental stress, or the like exceeds a predetermined threshold.
[0016]
[Means for Solving the Problems]
To achieve the above object, a cardiac treatment device of the present invention includes a nerve stimulation unit that generates a nerve stimulation signal for stimulating the vagus nerve, a heart stimulation unit that generates a heart stimulation pulse for stimulating the heart, Changes by exercise or mental stress Sensor means for sensing biological information, nerve stimulation means, and control means connected to the sensor means are provided. And this control means is the output of the sensor means. From this, when it is determined that the degree of excitement of the sympathetic nerve is intense, so that the nerve stimulation is stronger than when the degree of excitement is determined to be small, It is characterized by adjusting a parameter of a nerve stimulation signal.
[0017]
As a preferred form of the present invention, the nerve stimulation signal parameter is at least one of a period between pulses, a pulse width, a pulse number, a pulse current, a pulse voltage, a delay time, a pause time, and the number of repetitions, or these It is characterized by being a plurality of combinations selected from.
The sensor means detects ventricular contractility, and in particular, sensor means for detecting an electrocardiogram QT time, an electrocardiogram area, a precursor discharge time, a stroke volume, a ventricular pressure, or the like is used.
[0018]
Furthermore, the nerve stimulation means of the heart treatment device of the present invention generates a nerve stimulation signal when the contractility of the ventricle is larger than a predetermined threshold value, and stops generating the nerve stimulation signal when it is small. It is said.
[0020]
In the heart treatment apparatus of the present invention, the heart stimulation means stimulates the heart at a predetermined rate, and cancels the generation of the heart stimulation pulse in response to the cardiac contraction detection means, thereby lowering the lower limit of the heart rate. It is characterized by maintaining.
[0021]
As described above, according to the heart treatment device of the present invention, by performing optimal nerve stimulation according to the patient's situation, it is possible to avoid side effects of nerve stimulation and excessive reduction in heart rate, power consumption saving, etc. The effect is obtained.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of a heart treatment device according to the present invention will be described in detail with reference to FIG. In this specification, the “event” of the heart includes a contraction phenomenon that occurs in the heart (atrium and / or ventricle) regardless of whether it is caused by a stimulus or spontaneously.
The heart treatment device 1 includes a control unit 2, a ventricular stimulation unit 3 that generates a right ventricular stimulation pulse that stimulates the right ventricle 14 of the heart 13, a ventricular contraction detection unit 4 that detects spontaneous contraction of the right ventricle 14, and a right side of the heart 13. An atrial stimulation means 5 for generating a right atrial stimulation pulse for stimulating the atrium 15, an atrial contraction detection means 6 for detecting spontaneous contraction of the right atrium 15, a neural stimulation means 7 for generating a neural stimulation pulse for stimulating the vagus nerve 18, and a sensor Consists of means 8.
[0023]
The ventricular stimulation means 3 and the ventricular contraction detection means 4 are connected to the ventricular stimulation / detection electrode 10 by a common ventricular electrode lead 9, and the atrial stimulation means 5 and the atrial contraction detection means 6 are similarly connected to the atrium via the atrial electrode lead 11. Connected to the stimulation / detection electrode 12. Ventricular stimulation / detection electrode 10 and atrial stimulation / detection electrode 12 are disposed in right ventricle 14 and right atrium 15 of heart 13.
[0024]
In general, as the electrodes for the heart, there are a heart muscle, a so-called myocardium electrode embedded in the myocardium, and a catheter electrode for inserting the electrode to the heart via the vena cava. FIG. 2 shows an example of a catheter electrode, but both the ventricular electrode lead 9 and the atrial electrode lead 11 are initially guided from the vena cava to the right atrium 15 of the heart 13. The atrial electrode lead 11 inserted into the right atrium 15 from the vena cava is inserted so as to be hooked into the bag-shaped right atrial appendage protruding from the right atrial wall, and the atrial electrode lead 11 is bent into a J shape. 12 is placed in contact with the inner wall of the right atrial appendage. Similarly, the ventricular electrode lead 9 inserted into the right atrium 15 from the vena cava enters the right ventricle 14 through the atrioventricular valve, and the ventricular stimulation / detection electrode 10 provided at the distal end of the ventricular electrode lead 9 is on the right. It arrange | positions so that the lowest part of the ventricle 14 may be contacted.
[0025]
Although not shown in FIG. 2, the nerve stimulation means 7 is connected to the nerve stimulation electrode 17 through the nerve electrode lead 16, and the nerve stimulation electrode 17 is wound around the vagus nerve 18 and fixed. The region around which the nerve stimulation electrode 17 is wound is preferably the cervical region or the right center position of the outer carotid artery. Further, the nerve stimulation electrode 17 can be arranged to stimulate the vagus nerve 18 adjacent to the blood vessel wall by placing a catheter electrode in the blood vessel. In that case, the subclavian vein is suitable as the placement region.
[0026]
The control means 2 of the heart treatment apparatus 1 shown in FIG. 1 includes a ventricular detection continuation counter 19 connected to the ventricular stimulation means 3 and the ventricular contraction detection means 4, a ventricular detection continuation count setting value storage means 20, and a ventricular detection continuation counter. 19 and ventricular detection continuation frequency setting value storage means 20 supplied with ventricular detection continuation frequency comparison means 21, OR circuit 22 supplied with the output of atrial contraction detection means 6 and the input to atrial stimulation means 5, An atrioventricular delay (AVD) timer 23 to which the output of the OR circuit 22 and the output of the ventricular contraction detecting means 4 are supplied, and a first AVD storage means 24 for storing a first AVD set value which is a normal atrioventricular delay time. A second AVD storage means 25 for storing a second AVD set value shorter than the normal atrioventricular delay time, and A for selecting either the first AVD storage means 24 or the second AVD storage means 25 D selection means 26, AVD comparison means 27 for detecting that the time counted by AVD timer 23 coincides with the set value selected by AVD selection means 26, and an atrial stimulation interval timer to which the output of OR circuit 22 is supplied 28, an atrial stimulation interval set value storage means 29, a comparison means 30 that emits an output when the count value of the atrial stimulation interval timer 28 matches the set value stored in the atrial stimulation interval setting value storage means 29, It comprises a nerve stimulation parameter table storage means 31 to which the output of the sensor means 8 is supplied, and a nerve stimulation control means 32 to which the output of the OR circuit 22 is supplied and which controls the timing of the nerve stimulation.
[0027]
FIG. 3 shows a QT time sensor which is one specific example of the sensor means 8. The sensor means 8 is supplied with an intraventricular electrocardiogram from the ventricular detection electrode 10 only when the ventricular stimulation is performed, and the QT time counting means 33 to which the output of the AVD comparison means 27 of the control means 2 in FIG. 1 is supplied. It is comprised from the T wave detection means 34 which detects a T wave from an intraventricular electrocardiogram. The output of the T wave detecting means 34 is supplied to the QT time measuring means 33, and the QT time is measured and supplied to the nerve stimulation parameter table storage means 31 of the control means 2 in FIG.
[0028]
Here, the measurement of the QT time will be described using the intraventricular electrocardiogram of FIG. This intraventricular electrocardiogram is slightly different from the electrocardiogram measured by attaching electrodes to the normal body surface shown in FIG. 17B. That is, the ventricular electrocardiogram has almost no P wave for observing the contraction of the atrium, and is composed of a QRS wave starting from the stimulation of the ventricle and a T wave having a different polarity from the QRS wave. The T wave is a wave that is generated when the ventricular contraction relaxes, that is, when the ventricular excitement ends.
As already described, the QT time is the time from when the right ventricle 14 is stimulated to contract the ventricular muscle until the ventricular muscle relaxes and returns to its original state. When measuring the QT time using an intraventricular electrocardiogram, the time differentiation of the T wave is taken, and the point at which the differential value (slope) becomes the maximum negative is taken as the T point, and the QT time is measured. This QT time is biological information related to typical ventricular contractility, which is about 400 ms in a normal state, that is, normal, but sympathetic nerve activity is enhanced when intense exercise or stress is felt. Then, it becomes shorter and becomes less than half of the normal time.
[0029]
In the first embodiment of the heart treatment apparatus of the present invention, the sensor means 8 of FIG. 1 is constituted by the QT time sensor of FIG.
Hereinafter, the operation of the first embodiment of the heart treatment device of the present invention shown in FIG. 1 will be described. First, when the contraction of the right atrium 15 is detected by the atrial contraction detection means 6, the atrial contraction detection means 6 sends its output to the atrial stimulation interval timer 28 and the AVD timer 23 via the OR circuit 22, and the atrium is detected. The stimulation interval timer 28 is reset and the counting of the AVD timer 23 is started.
[0030]
The AVD selection unit 26 selects the normal atrioventricular delay time setting value, for example, 150 ms, stored in the first AVD storage unit 24 in the initial state. In a normal cardiac activity state, spontaneous ventricular contraction occurs after the AVD timer 23 starts and before the set value stored in the first AVD storage means 24 is counted. Further, it is reset by the output of the ventricular contraction detecting means 4. For this reason, the AVD timer 23 does not count the set value stored in the first AVD storage unit 24 set in the AVD selection unit 26. Therefore, in this case, no output from the AVD comparison means 27 is obtained, and the ventricular stimulation means 3 is not supplied with the output of the AVD comparison means 27, so that no forced ventricular stimulation is performed.
[0031]
If no spontaneous ventricular contraction occurs within the normal atrioventricular delay time stored in the first AVD storage means 24, no output is obtained from the ventricular contraction detection means 4, so the AVD timer 23 stops. Continue counting. That is, the AVD timer 23 continues counting until it matches the set value stored in the first AVD storage means 24 selected by the AVD selection means 26, and generates an output from the AVD comparison means 27 at the time of matching. .
[0032]
The output of the AVD comparison means 27 is sent to the ventricular stimulation means 3, and the right ventricle 14 is stimulated by the ventricular stimulation electrode 10 through the ventricular electrode lead 9. At the same time, it is added to the ventricular detection continuation counter 19 to reset the ventricular detection continuation counter 19. The output of the AVD comparison means 27 is supplied to the QT time counting means 33 of the sensor means 8 shown in FIG.
[0033]
The ventricular detection continuation counter 19 that is reset by ventricular stimulation (output of the AVD comparison means 27) is incremented every time the ventricular contraction detection means 4 detects spontaneous ventricular contraction, and the ventricular detection continuation count setting value storage means 20 When the contraction of the ventricle is continuously detected for the number of times stored in (a specific example, about 3 to 10 times), the ventricular detection continuation number comparison means 21 outputs an output. The output of the ventricular detection continuation number comparison means 21 is supplied to the AVD selection means 26. The AVD selection unit 26 switches the set value from the set value of the first AVD storage unit 24 to the set value of the second AVD storage unit 25 based on the output from the ventricular detection continuation number comparison unit 21.
[0034]
The set value stored in the second AVD storage means 25 is set to a set value, for example, 100 ms, which is smaller than about 150 ms, which is a normal atrioventricular delay time. Here, when the atrioventricular delay time of 100 ms is set as a set value, since the ventricular contraction detecting means 4 does not detect the ventricular contraction while the AVD timer 23 counts 100 ms, the AVD timer 23 always stores the second AVD storage means 25 in the second AVD storage means 25. In order to count the stored setting values, an output is obtained from the AVD comparison means 27 each time.
[0035]
The output of the AVD comparison means 27 is applied to the ventricular stimulation means 3, the ventricular detection continuation counter 19, and the sensor means 8 (QT time counting means 33 in FIG. 3). Thereby, the QT time is measured as biological information representing the degree of excitement of the sympathetic nerve.
The AVD selection means 26 switches from the first AVD storage means 24 to the atrioventricular delay time setting value of the second AVD storage means 25 because it is necessary to forcibly perform ventricular stimulation in order to measure the QT time. is there.
[0036]
The T-wave detection means 34 in the sensor means 8 shown in FIG. 3 forcibly gives a pulse to the ventricular stimulation means 3 and detects the T-wave only when the right ventricle 14 is stimulated. When a T wave is detected, an output is sent to the QT time counting means 33 and the count of the QT time counting means 33 is stopped. Then, the measured QT time is sent from the QT time counting means 33 to the nerve stimulation parameter table storage means 31 of the control means 2, and a parameter corresponding to the QT time is selected.
[0037]
The nerve stimulation parameters selected according to the QT time include the number of pulses in the nerve stimulation pulse train, the delay time from the atrial event to stimulation of the vagus nerve 18, the amplitude of the nerve stimulation pulse, and the nerve stimulation pulse. The pulse width of the neural stimulation pulse, the inter-pulse period of the neural stimulation pulse, the number of neural stimulation pulse trains (number of repetitions), the time between the neural stimulation pulse trains (pause time), the on / off of neural stimulation (neural stimulation flag), etc. The vagus nerve 18 can be stimulated by combining these parameters according to the patient's situation. FIG. 18 is a diagram for explaining the nerve stimulation parameters, which are shown in comparison with a cardiac event in an electrocardiogram.
[0038]
Tables 1 to 3 show some examples of controlling the nerve stimulation parameters. In any control example, when the QT time is in the normal range (greater than QTnormal × 0.9), the nerve stimulation flag is set to OFF and the vagus nerve 18 is not stimulated, but the QT time is shorter than the normal range. When this happens, the nerve stimulation flag is set to ON, and the nerve stimulation parameters are controlled according to the degree of shortening to stimulate the vagus nerve 18. Table 1 is an example of controlling the number of pulses for nerve stimulation according to the QT time. As the QT time becomes shorter than the normal QT time, the number of nerve stimulation pulses is increased and the number of stimulations is increased. Yes. Table 2 controls the period between pulses according to the QT time. That is, as the QT time becomes shorter than the normal QT time, the inter-pulse period of the nerve stimulation pulse is reduced to increase the stimulation frequency. Table 3 shows an example in which the delay time from the atrial event to the nerve stimulation (delay time) is changed according to the QT time. As the QT time becomes shorter than the normal QT time, the timing for performing the nerve stimulation is determined from the atrial event. I am trying to delay.
[0039]
[Table 1]

[0040]
[Table 2]

[0041]
[Table 3]

[0042]
The nerve stimulation parameter table storage means 31 stores tables relating to nerve stimulation parameters as shown in Tables 1 to 3, and based on the QT time measured by the QT time measuring means 33 in FIG. Whether or not to perform, if so, the parameter is selected and determined and sent to the nerve stimulation control means 32.
[0043]
When the atrial contraction detection means 6 detects the contraction of the right atrium 15 in the state where the nerve stimulation flag is turned on in the nerve stimulation control means 32, the atrial stimulation interval timer is output via the OR circuit 22 by the output of the atrial contraction detection means 6. 28 is reset. In the atrial stimulation interval set value storage means 29, a time corresponding to the heart beat period in the normal state is set, and if the next atrial contraction is not detected within that time, the atrial stimulation interval timer 28 The count value reaches the set value stored in the atrial stimulation interval set value storage means 29, and the comparison means 30 generates an output. Atrial stimulation is performed by the output of the comparison means 30, and the output of the comparison means 30 is supplied to the nerve stimulation control means 32 via the OR circuit 22. The nerve stimulation control means 32 sends a signal to the nerve stimulation means 7 based on the control of various parameters corresponding to the QT time shown in Tables 1 to 3 selected in the nerve stimulation parameter table storage means 31, and the nerve electrode lead 16, The vagus nerve 18 is stimulated via the nerve stimulation electrode 17. It should be noted that the parameters shown in Tables 1 to 3 are not only used alone, but can be selected in several combinations depending on the patient's condition.
Thus, the state of the patient's exercise and mental stress is detected based on the QT time. When the exercise or mental stress is large (large), relatively strong nerve stimulation is performed. When the exercise or mental stress is small (small), relatively weak nerve stimulation is performed. Or control not to perform nerve stimulation.
[0044]
FIG. 5 is a flowchart for explaining the operation of the first embodiment of the present invention.
Hereinafter, the operation of this example will be described in detail with reference to the flowchart of FIG. First, the nerve stimulation flag of the nerve stimulation control means 32 is turned off (step S1). Next, the ventricular detection continuation counter 19 is reset (step S2), the atrial stimulation interval timer 28 is further reset (step S3), and the initialization of the entire system is completed.
[0045]
Next, it is determined whether or not atrial contraction is detected by the atrial contraction detection means 6 (step S4). If no atrial contraction is detected in the determination step S4, it is determined whether or not the atrial stimulation interval timer 28 has timed out (step S5). If it is determined that the time-out has occurred, the comparison means 30 outputs to the atrial stimulation means 5. Is emitted and atrial stimulation is performed (step S6). If it is determined in step S5 that the time-out has not occurred, the detection of atrial contraction is awaited again. When an atrial contraction is detected in the determination step S4, the atrial stimulation interval timer 28 is reset, starts counting again from the beginning (step S7), and starts counting the AVD timer 23 (step S8).
[0046]
Next, it is determined whether or not the nerve stimulation flag of the nerve stimulation control means 32 is turned on (step S9). If the nerve stimulation flag is turned on, the nerve stimulation control means 32 changes to the nerve stimulation means 7. A signal is emitted and the vagus nerve 18 is stimulated (step S10). If it is determined in the determination step S9 that the nerve stimulation flag is OFF, the processing proceeds to the next step without performing nerve stimulation.
[0047]
When the ventricular contraction detection means 4 detects the contraction of the ventricle, the ventricular detection continuation counter 19 is incremented, and whether or not this value has reached the set value stored in the ventricular detection continuation count setting value storage means 20, that is, It is determined whether or not ventricular contraction has been continuously detected by the number of 3 to 10 times stored in the ventricular detection continuation number setting value storage unit 20 (step S11). When the count value of the ventricular detection continuation counter 19 reaches the set value, an output is given from the ventricular detection continuation number comparison means 21 to the AVD selection means 26, and the AVD selection means 26 stores in the second AVD storage means 25. The set value is selected (step S12). Since the set value of the atrioventricular delay time stored in the second AVD storage means 25 is set to be shorter than the normal value, the AVD timer 23 is set before the ventricular contraction detection means 4 detects the spontaneous ventricular contraction. Since the set value of the second AVD storage means 25 is reached, an output is obtained from the AVD comparison means 27, forced ventricular stimulation is performed, and the ventricular detection continuation counter 19 is reset (step S13).
[0048]
In the determination step S11, when it is determined that the ventricular detection continuation counter 19 does not reach the set value stored in the ventricular detection continuation count setting value storage means 20, the ventricular detection continuation count comparison means 21 to the AVD selection means 26 Since the signal output to is not obtained, the AVD selection means 26 keeps selecting the setting value stored in the first AVD storage means 24 (step S14).
[0049]
Subsequently, it is determined whether or not ventricular contraction is detected by the ventricular contraction detection means 4 (step S15). If ventricular contraction is detected, the ventricular detection continuation counter 19 is incremented (step S16). If it is determined in step S15 that no ventricular contraction has been detected, whether the AVD timer 23 has timed out, that is, the count value of the AVD timer 23 is the first AVD storage unit 24 selected by the AVD selection unit 26. Alternatively, it is determined whether or not the set value of the second AVD storage means 25 has been exceeded (step S17).
[0050]
When it is determined in the determination step S17 that the AVD timer 23 has not timed out, the detection of the ventricular contraction is again waited. However, when the AVD timer 23 has timed out, an output is issued from the AVD comparison means 27 and the ventricle is detected. Ventricular stimulation from the stimulation means 3 is performed (step S18), the ventricular detection continuation counter 19 is reset (step S19), and the counting of the QT time counting means 33 is started (step S20).
[0051]
In this state, the T wave detection means 34 of the sensor means 8 performs time differentiation of the intracardiac electrocardiogram within a predetermined period corresponding to the T wave portion, and the negative slope of the T wave is maximized from the differential waveform. Is detected (step S21), and the counting of the QT time counting means 33 is stopped (step S22). When the negative maximum value of the T wave derivative is detected and the QT time of the electrocardiogram is measured, the measured value is sent to the nerve stimulation parameter table storage means 31 and compared with the QT time (QTnormal) as a standard value. The As a result of the comparison, it is first determined whether or not the QT time is within the normal range (step S23). If the QT time is within the normal range, the neurostimulation flag is turned off and the processing proceeds. For example, the nerve stimulation flag is turned on (step S24), and various parameters of nerve stimulation are selected according to the measured QT time (step S25).
[0052]
Next, an electrocardiogram area sensor which is another specific example of the sensor means 8 of the present invention is shown in FIG. This sensor means 8 measures the area of the electrocardiogram and uses it as the patient's biological information in relation to the QT time. The input to the ventricular stimulation means 3 in FIG. 1, ie, the output of the AVD comparison means 27 and the ventricular detection electrode 10 From the integration means 35 to which the intraventricular electrocardiogram information is given, and the negative maximum value detection means 36 for detecting the negative maximum value from the output of the integration means.
[0053]
Similarly to the QT time measurement, the integrating means 35 starts integration of the intraventricular electrogram shown in FIG. 4A sent when ventricular stimulation is performed by the ventricular stimulating means 3. This integrated waveform is shown in FIG. 4B. As is clear from FIG. 4B, when the QRS wave (negative polarity) is integrated from the reference potential Q point serving as a reference, the negative area value increases monotonously, but the T wave has the opposite polarity (positive) to the QRS wave. Therefore, at the stage of integrating the T wave, the negative integrated value is changed in a decreasing direction. The electrocardiogram area has a negative maximum value in a linear portion from the point S at which the QRS wave integration is completed to the point in time when detection of the T wave starts (assumed to be “X”). The negative maximum value detection means 36 detects the above value and sends this negative integrated maximum value to the nerve stimulation parameter table storage means 31 as biological information. Then, in the nerve stimulation parameter table storage unit 31, various parameters corresponding to the negative integrated maximum value are selected. As the nerve stimulation parameters, the number of pulses in the nerve stimulation pulse train, the delay time from the atrial event to the stimulation of the vagus nerve 18 (delay time), the amplitude of the nerve stimulation pulse, the pulse of the nerve stimulation pulse, as in the QT time. The width, the period between nerve stimulation pulses, the number of nerve stimulation pulse trains (number of repetitions), the time between nerve stimulation pulse trains (pause time), and on / off of nerve stimulation (neural stimulation flag) can be considered.
[0054]
Next, the heart treatment apparatus when the electrocardiogram area sensor shown in FIG. 6 is used will be described as a second embodiment of the present invention, and its operation will be described with reference to FIG.
Steps S1 to S19 and Steps S23 to S25 are the same as those in FIG.
[0055]
A description will be added from the stage of step S18 in which the AVD timer 23 times out, an output is issued from the AVD comparison means 27, and the ventricular stimulation from the ventricular stimulation means 3 is performed. When ventricular stimulation is performed, the ventricular detection continuation counter 19 is reset (step S19), and the integration calculation of the ventricular electrocardiogram information is started in the integration means 35 of the sensor means 8 (step S26).
At this time, as shown in FIG. 4A, the intraventricular electrocardiogram touches minus from the base potential, so that the integration calculation result is detected as a negative signal output. Next, it is determined whether or not a negative maximum value has been detected (step S27). If it is determined that a negative maximum value has been detected, whether or not this negative maximum value is within the normal range is determined. First, a determination is made (step S28). If it is within the normal range, the neurostimulation flag is turned off and the process proceeds. If it is outside the normal range, the nerve stimulation flag is turned on (step S24), and the measured negative Various parameters of nerve stimulation are selected according to the maximum value (step S25).
[0056]
Next, a third embodiment of the heart treatment device of the present invention will be described with reference to the block diagram of FIG. The same parts as those in the block configuration diagram of FIG. 1 are denoted by the same reference numerals, and the description will be simplified. In the third embodiment of the present invention, the configuration of the control means 2 and the configuration of the sensor means 8 are the same as those of the first and second embodiments of the present invention, which are shown in FIGS. 1 and 3 and FIGS. Since these are different, the following description will focus on this point.
[0057]
The third embodiment of the heart treatment device of the present invention shown in FIG. 8 is characterized in that a body motion sensor 43 is provided instead of the sensor means 8 of the first embodiment shown in FIG. As the body motion sensor 43, a piezoelectric sensor or an acceleration sensor is generally used. The sensor is disposed inside the housing of the heart treatment device 1 implanted under the chest, and is attached directly to the housing or on a circuit board. In a piezoelectric sensor, stress is applied to the piezoelectric crystal by physical movement, and the crystal generates an electrical signal. The acceleration sensor generally has a structure having a cantilever beam, and the beam causes movement / displacement due to acceleration to generate an electrical signal. The patient's body movement is detected from the frequency or intensity of the electrical signal, or the intensity within a certain frequency. When intense exercise is performed, changes in body movement (acceleration and vibration) increase, and the sympathetic nerve is also excited. Therefore, the degree of excitement of the sympathetic nerve can be measured by detecting acceleration and vibration with the body motion sensor 43. The output from the body motion sensor 43 is detected by the body motion detection means 45 at appropriate time intervals measured by the body motion detection timer 44, and the change in the amount of exercise at each measurement is measured.
[0058]
In the block diagram of FIG. 8, the control means 2 includes an OR circuit 22 to which an input to the atrial stimulation means 5 and an output of the atrial contraction detection means 6 are supplied, and an atrium that starts to count when the output of the OR circuit 22 is supplied. A chamber delay timer 40 (same as the AVD timer 23 in FIG. 1), an atrioventricular delay setting value storage means 41 for storing the atrioventricular delay time at normal time as a set value, and the time counted by the atrioventricular delay timer 40 An atrioventricular delay comparison unit 42 for detecting that the set value stored in the chamber delay set value storage unit 41 matches, an atrial stimulation interval timer 28 to which an output of the OR circuit 22 is supplied, and an atrial stimulation interval set value A storage means 29; and a comparison means 30 that emits an output when the count value of the atrial stimulation interval timer 28 matches the set value stored in the atrial stimulation interval set value storage means 29; The nerve stimulation parameter table storage means 31 to which the output from the body movement detection means 45 for detecting the output from the body movement sensor 43 at appropriate intervals measured by the body movement detection timer 44 is supplied, and the output of the OR circuit 22 The nerve stimulation control means 32 is supplied and controls the timing of nerve stimulation.
[0059]
The operation of the third embodiment of the heart treatment device of the present invention will be described below.
In FIG. 8, when the atrial contraction detection means 6 detects the contraction of the right atrium 15, the atrial contraction detection means 6 sends its output to the atrial stimulation interval timer 28 and the atrioventricular delay timer 40 via the OR circuit 22. The stimulation interval timer 28 is reset, and the counting of the atrioventricular delay timer 40 is started.
[0060]
In the atrioventricular delay set value storage means 41, a delay time allowed for the patient from the time when the atrium contracts to the time when the ventricle contracts is set. Usually, before the set value is counted, spontaneously When the ventricular contraction occurs, the atrioventricular delay timer 40 is reset by the output of the ventricular contraction detection means 4 each time. For this reason, the atrioventricular delay timer 40 does not count to the set value stored in the atrioventricular delay set value storage means 41, so that no output from the atrioventricular delay comparison means 42 is obtained, and the ventricular stimulation means 3 The output of the room delay comparison means 42 is not supplied. Therefore, forced ventricular stimulation is not performed.
[0061]
If no spontaneous ventricular contraction occurs within the atrioventricular delay time stored in the atrioventricular delay setting value storage means 41, no output is obtained from the ventricular contraction detection means 4, so the atrioventricular delay timer 40 is stopped. Continue counting without doing. That is, the atrioventricular delay timer 40 continues counting until it matches the set value stored in the atrioventricular delay set value storage means 41, and generates an output from the atrioventricular delay comparing means 42 at the time of matching. The output of the atrioventricular delay comparison means 42 is sent to the ventricular stimulation means 3, and the right ventricle 14 is stimulated by the ventricular stimulation electrode 10 through the ventricular electrode lead 9.
[0062]
On the other hand, when the atrial contraction detection means 6 detects the contraction of the right atrium 15, the atrial stimulation interval timer 28 is reset via the OR circuit 22 by the output of the atrial contraction detection means 6. In the atrial stimulation interval set value storage means 29, a time corresponding to the heart beat period in the normal state is set, and if the next atrial contraction is not detected within that time, the atrial stimulation interval timer 28 The count value reaches the set value stored in the atrial stimulation interval set value storage means 29, and the comparison means 30 generates an output. Atrial stimulation is performed by the output of the comparison means 30, and the output of the comparison means 30 is supplied to the nerve stimulation control means 32 via the OR circuit 22, and the vagus nerve 18 is stimulated by the nerve stimulation means 7. Here, the frequency and intensity of nerve stimulation are adjusted by selecting parameters stored in the nerve stimulation parameter table storage unit 31 according to the patient's condition. Selection of this parameter is performed by detecting the output of the body motion sensor 43 represented by the acceleration sensor by the body motion detection means 45.
[0063]
Next, a fourth embodiment of the heart treatment device of the present invention will be described with reference to the block diagram of FIG. The same components as those in the block diagram of FIG.
The fourth embodiment differs from the third embodiment only in the sensor portion that selects the parameters of the nerve stimulation parameter table storage means 31. In the fourth embodiment, a blood sensor 46 provided on either the atrial electrode or the ventricular electrode is used. The biological information detected by the blood sensor 46 includes central venous blood temperature, venous oxygen saturation, blood pH, blood catecholamine amount, etc., all of which are autonomic nerves (especially sympathetic nerves) due to exercise and stress. ) Is related to the degree of excitement.
[0064]
Hereinafter, the operation of the fourth embodiment of the heart treatment device of the present invention will be described, but the outline description of the entire block configuration diagram will be omitted because it is the same as that of the third embodiment shown in FIG. In the fourth embodiment, a blood sensor 46 attached to the ventricular stimulation / detection electrode 10 or the ventricular electrode lead 9 provided in the right ventricle 14 is used. In FIG. 9, the ventricular stimulation / detection electrode 10 or the ventricular electrode lead 9 is depicted as being separated from the ventricular stimulation / detection electrode 10 for easy understanding, but is integrally formed in the heart 13.
[0065]
The blood sensor 46 disposed in the right ventricle 14 detects various biological information in the blood related to the degree of excitement of the sympathetic nerve, and the detected information is sent to the nerve stimulation parameter table storage means 31. A parameter for controlling the frequency and intensity of stimulation of the vagus nerve 18 is selected.
[0066]
Next, a fifth embodiment of the present invention will be described based on the block configuration diagram shown in FIG. Also in the embodiment of FIG. 10, blocks in the same part as those shown in FIG. 8 and FIG. The fifth embodiment is different from the third and fourth embodiments in that a respiration sensor 50 for detecting biological information for selecting parameters in the nerve stimulation parameter table storage unit 31 is provided. The respiration sensor 50 includes an impedance measurement means 51 connected to the atrial electrode lead 11, a respiration detection means 52 to which an output of the impedance measurement means is applied, and a respiration detection timer 53 that measures the timing of respiration detection. . The impedance measuring unit 51 generates a constant current measurement waveform with a strength that does not stimulate the heart between the titanium housing of the heart treatment device 1 implanted under the chest and the atrial stimulation / detection electrode 12 via the atrial electrode lead 11. Impedance is measured by superimposing and applying, and measuring the voltage across it. Thereby, the respiration sensor 50 can detect the expansion and contraction of the thorax from the change in impedance between the right atrium 15 and the chest, and thus can know the respiration state of the patient. The respiratory sensor 50 may be configured to connect the impedance measuring means 51 and the ventricular electrode lead 9 so as to know the patient's respiratory state from the change in impedance between the right ventricle 14 and the chest.
[0067]
The operation of the fifth embodiment of the heart treatment device of the present invention will be described below. When the excitement level of the sympathetic nerve increases due to exercise or stress, respiration (respiration rate or respiration rate) becomes intense, and this is captured as an impedance change by the impedance measuring means 51 of the respiration sensor 50 via the atrial electrode lead 11. The respiration detection means 52 processes the impedance waveform measured by the impedance measurement means 51 at appropriate intervals counted by the respiration detection timer 53, and the respiration rate is determined from the speed of impedance change, and the respiration rate is determined from the magnitude. The detected parameters of the nerve stimulation parameter table storage unit 31 are selected according to the respiration rate and respiration rate. Based on the selected parameter, a signal is emitted from the nerve stimulation control means 32 to the nerve stimulation means 7, and the nerve stimulation means 7 stimulates the vagus nerve 18 appropriately according to the patient's condition.
[0068]
The third to fifth embodiments of the heart treatment device of the present invention shown in FIG. 8 to FIG. 10 will be described collectively based on the flowchart of FIG. Since the different part of these three embodiments is the part of the sensor means, in the following description, these will all be described as biological information detection sensors. This biological information detection sensor represents a body motion sensor, a blood sensor, and a respiration sensor, respectively, according to each embodiment.
First, the nerve stimulation flag of the nerve stimulation control means 32 is turned off (step S30), the biological information detection timer included in the biological information sensor is started (step S31), and the atrial stimulation interval timer 28 is also started. Is reset to start counting (step S32).
[0069]
Next, it is determined whether or not the biological information detection timer of the biological information detection sensor has timed out (step S33). If the biometric information detection timer has timed out, the biometric information is detected when the time for detecting biometric information is reached (step S34), and the biometric information detection timer is reset again (step S35). Subsequently, based on the detection of biological information by the biological information detection sensor, an optimal nerve stimulation parameter for the patient is selected from the table of the nerve stimulation parameter table storage unit 31 (step S36). The selection of the nerve stimulation parameter here includes selection of whether or not to perform nerve stimulation. When nerve stimulation is performed, the nerve stimulation flag is turned on. If it is determined in the determination step S33 that the biological information detection timer has not timed out, the detection of the atrial contraction is awaited without detecting the biological information.
[0070]
Subsequently, the atrial contraction detection means 6 determines whether or not an atrial contraction is detected (step S37). If atrial contraction is detected, the atrial stimulation interval timer 28 is reset (step S38), and then the atrioventricular delay timer 40 is reset to start counting (step S39). Next, it is determined whether or not the nerve stimulation flag of the nerve stimulation control means 32 is turned on (step S40). If the nerve stimulation flag is turned on, the nerve stimulation control means 32 changes to the nerve stimulation means 7. A signal is emitted and the vagus nerve 18 is stimulated (step S41). If the nerve stimulation flag is off in the determination step S40, the process proceeds to the next step without performing nerve stimulation.
[0071]
If it is determined in step S37 that no atrial contraction has been detected, whether or not the atrial stimulation interval timer 28 has timed out, that is, the time measured by the atrial stimulation interval timer 28 is stored in the atrial stimulation interval set value storage means 29. It is determined whether the set value is exceeded (step S42). If it is determined that a time-out has occurred, an output is issued from the comparison means 30 to the atrial stimulation means 5, and atrial stimulation is performed (step S43).
[0072]
In step S41, after the vagus nerve 18 has been stimulated, it is determined again whether the biological information detection timer has timed out (step S44). If it is determined that a time-out has occurred, biometric information detection (step S45), biometric information detection timer reset (step S46), and nerve stimulation parameter setting (step S47) are performed as in steps S34 to S36. The steps are sequentially performed, and the next ventricular contraction detection step (step S48) is entered. Note that the selection of the nerve stimulation parameter here includes selection of whether or not to perform nerve stimulation. When nerve stimulation is performed, the nerve stimulation flag is turned on.
If it is determined in the determination step S44 that the biometric information detection timer has not timed out, that is, if it is determined that it is not yet time to measure, the next ventricular contraction detection step (step S48) is entered.
[0073]
Next, when the contraction of the ventricle is detected in the determination step S48, the atrioventricular delay timer 40 stops counting (step S49) and returns to the determination step S33 again. When the ventricular contraction is not detected in the determination step S48, it is determined whether or not the atrioventricular delay timer 40 has timed out, that is, whether or not the set value stored in the atrioventricular delay set value storage means 41 has been exceeded. (Step S50). If it is determined in the determination step S50 that a time-out has occurred, an output is issued from the atrioventricular delay comparison means 42 to the ventricular stimulation means 3, and ventricular stimulation is performed (step S51). After the ventricular stimulation is performed, the process returns to the determination step S33 again. If it is determined in the determination step S50 that the atrioventricular delay timer 40 has not timed out, the process returns to the determination step S44 and the biometric information detection timer times out again. It is determined whether or not
[0074]
FIG. 12 is a block diagram showing a sixth embodiment of the heart treatment device of the present invention. A difference from the third to fifth embodiments shown in FIGS. 8 to 10 is a portion in which the time change rate (time differentiation) dp / dt of the intraventricular pressure is detected as the type of biological information. The same components are denoted by the same reference numerals.
In FIG. 12 showing the sixth embodiment of the present invention, a pressure sensor 60 provided in the right ventricle 14, a ventricular contractile ventricular pressure sensor 61 that receives the output of the pressure sensor 60, and a ventricular contraction detecting means 4. An OR circuit 62 for supplying the output and the output of the atrioventricular delay comparing means 42, that is, information for instructing ventricular stimulation, and supplying the output to the ventricular contractile ventricular pressure sensor 61 is newly added. The ventricular contractile ventricular pressure sensor 61 monitors the output of the differentiation circuit 63 at the timing of the differentiation circuit 63 that differentiates the signal input from the pressure sensor 60 with respect to time and the OR circuit 62, and holds the maximum value. The maximum value holding circuit 64 is configured.
[0075]
The operation of the sixth embodiment of the present invention will be described below. The pressure sensor 60 measures the pressure when the ventricle contracts, and is usually provided in the ventricular stimulation / detection electrode 10 or the ventricular electrode lead 9. The pressure sensor 60 measures the intraventricular pressure, and the signal obtained by differentiating the signal from the pressure sensor 60 by the differentiation circuit 63 is dp / dt. The maximum differential value held in the maximum value holding circuit 64 is max. dp / dt. This differential maximum value max dp / dt is such that the maximum value within a predetermined period, for example, a period of 100 ms, is held from the timing of the output of the OR circuit 62, that is, the timing of detection of ventricular contraction or the timing of stimulation to the ventricle. I have to. The held max dp / dt is sent to the nerve stimulation parameter table storage means 31 of the control means 2, and an optimum stimulation parameter for the patient is selected according to this value.
[0076]
Here, since the max dp / dt of the ventricle increases due to intense exercise or mental stress, the magnitude of exercise or mental stress can be detected from the value of max dp / dt. By utilizing this property, when max dp / dt is large, strong nerve stimulation is performed, and when max dp / dt is small, weak nerve stimulation is performed or nerve stimulation is not performed.
[0077]
FIG. 13: is a block block diagram which shows 7th Embodiment of the heart treatment apparatus of this invention. The difference from the sixth embodiment shown in FIG. 12 is the type of biological information and its detection sensor. In the sixth embodiment, the maximum value of the time change rate (time differentiation) dp / dt of the ventricular pressure is used as the biological information. In the seventh embodiment shown in FIG. 13, the ventricular contractile impedance sensor is used. 70 is used. Since the other block configuration is exactly the same as that of the sixth embodiment, the same block configuration is denoted by the same reference numeral.
[0078]
Specific examples of the ventricular contractile impedance sensor 70 are shown in FIGS. FIG. 14 shows an example of a ventricular precursor time sensor 71, and FIG. 15 shows an example of a stroke volume sensor 75.
A ventricular contractile impedance sensor 70 shown in FIG. 13 using the ventricular precursor time sensor 71 shown in FIG. 14 will be described below as a seventh embodiment of the present invention.
The ventricular progenitor time is the time from the start of electrical ventricular contraction (ventricular contraction detection or ventricular stimulation) until the ventricle actually starts ejecting blood. From this ventricular progenitor time, some degree of exercise and mental stress can be detected.
[0079]
The ventricular progenitor time sensor 71 includes a progenitor time measuring unit 72 that starts time measurement triggered by ventricular contraction detection or ventricular stimulation, an impedance measuring unit 73 that monitors changes in the volume of the ventricle, and an impedance measuring unit 73. It comprises ventricular ejection detection means 74 that receives the output and determines that blood ejection has started when there is a predetermined decrease in the ventricular volume.
[0080]
Hereinafter, the operation of the seventh embodiment will be described. In FIG. 13, the output of the ventricular contraction detecting means 4 and the output of the atrioventricular delay comparing means 42 are supplied to an OR circuit 62. Therefore, an output is obtained in the OR circuit 62 when the contraction of the ventricle is detected or when the ventricular stimulation is performed, and this output is supplied to the precursor time measuring means 72 of the ventricular precursor time sensor 71 (FIG. 14). Then, measurement of the precursor ejection time is started. The ventricular stimulation / detection electrode 10 is connected to the impedance measuring means 73 of FIG. 14 via the ventricular electrode lead 9, and the impedance measuring means 73 detects the change in impedance when the volume of the ventricle changes. Detects volume fluctuations.
[0081]
The output of the impedance measuring means 73 is sent to the ventricular ejection detecting means 74. The ventricular ejection detecting means 74 monitors the output from the impedance measuring means 73, that is, the impedance change, and there is a predetermined decrease in the ventricular volume. If it is determined that the blood ejection has started, the time counting of the precursor time counting means 72 is stopped. The measured ventricular progenitor time is sent to the nerve stimulation parameter table storage unit 31 in FIG. 13, and parameters for nerve stimulation optimal for the patient are selected according to the ventricular progenitor time. Since this precursor release time is shortened by exercise and mental stress, the stimulation of the vagus nerve should be strengthened when the ventricular precursor release time is small.
[0082]
FIG. 15 is a block diagram showing a configuration of a stroke volume sensor 75 showing an example of the ventricular contractile impedance sensor 70 of FIG.
Stroke volume is the amount obtained by subtracting the end-systolic ventricular volume from the end-diastolic ventricular volume in a single ventricular contraction, and the amount of exercise and mental stress can be determined from this stroke volume. Is.
An example in which the stroke volume sensor 75 in FIG. 15 is employed as the ventricular contractile impedance sensor 70 in FIG. 13 will be described below as an eighth embodiment of the present invention.
[0083]
The stroke volume sensor 75 shown in FIG. 15 includes an end-diastolic volume detection means 76 that detects a ventricular end-diastolic volume by using ventricular contraction detection or ventricular stimulation as a trigger, and an impedance that monitors a change in ventricular volume by impedance change. From the output of the measuring means 77, the end-diastolic volume detecting means 76, and the end-diastolic volume detecting means 76 for detecting the minimum value of the ventricular volume as the end-systolic volume from the output of the impedance measuring means 77 following the detection of the end-diastolic volume. The stroke volume calculating means 79 calculates the stroke volume of the ventricle by subtracting the output of the end volume detecting means 78.
[0084]
Hereinafter, the operation of the eighth embodiment of the present invention will be described. In FIG. 13, as described above, an output is obtained in the OR circuit 62 when ventricular contraction is detected or when ventricular stimulation is performed. The output is supplied to the end-diastolic volume detection means 76 of the stroke volume sensor 75 (FIG. 15). On the other hand, the impedance measuring means 77 connected to the ventricular stimulation / contraction electrode 10 calculates the volume of the ventricle from the measured impedance and sends it to the end-diastolic volume detection means 76 and the end-systolic volume detection means 78. The end-diastolic volume detecting means 76 detects the ventricular volume at the time of detecting ventricular contraction or ventricular stimulation based on the output from the impedance measuring means 77, and sets this volume as the ventricular end-diastolic volume. The end systolic volume detecting means 78 monitors the output of the impedance measuring means 77 and detects the minimum value of the ventricular volume as the ventricular end systolic volume.
[0085]
The stroke volume calculating means 79 calculates the output difference between the end-diastolic volume detecting means 76 and the end-systolic volume detecting means 78, that is, the difference between the end-diastolic ventricular volume and the end-systolic ventricular volume. Is sent to the nerve stimulation parameter table storage means 31 of FIG. 13 as a stroke volume. Then, a parameter for nerve stimulation optimal for the patient is selected according to the stroke volume. This stroke volume may increase or decrease due to exercise or mental stress. Therefore, when the stroke volume is large, the stimulation of the vagus nerve should be strengthened.
[0086]
Next, the operation of the sixth to eighth embodiments of the present invention shown in FIGS. 12 to 15 will be described in detail using the flowchart of FIG.
First, the nerve stimulation flag of the nerve stimulation control means 32 is turned off (step S60). At the same time, the atrial stimulation interval timer 28 is reset and counting starts (step S61).
[0087]
In this state, the initial setting is completed. Next, the atrial contraction detection means 6 determines whether or not an atrial contraction is detected (step S62). If atrial contraction is detected, the atrial stimulation interval timer 28 is reset (step S63), and then the atrioventricular delay timer 40 is reset to start counting (step S64). Next, it is determined whether or not the nerve stimulation flag of the nerve stimulation control means 32 is turned on (step S65). If the nerve stimulation flag is turned on, the nerve stimulation control means 32 changes to the nerve stimulation means 7. A signal is emitted and the vagus nerve 18 is stimulated (step S66). If the nerve stimulation flag is off in the determination step S65, the process proceeds to the next step without performing nerve stimulation.
[0088]
If it is determined in step S62 that no atrial contraction has been detected, whether or not the atrial stimulation interval timer 28 has timed out, that is, the time measured by the atrial stimulation interval timer 28 is stored in the atrial stimulation interval set value storage means 29. It is determined whether or not the set value is exceeded (step S67). If it is determined that a time-out has occurred, an output is issued from the comparison means 30 to the atrial stimulation means 5, and atrial stimulation is performed (step S68).
[0089]
Subsequently, it is determined whether or not the ventricle is contracted (step S69). When the contraction of the ventricle is detected, the counting of the atrioventricular delay timer 40 is stopped (step S70). When the ventricular contraction is not detected in the determination step S69, it is determined whether or not the atrioventricular delay timer 40 has timed out, that is, whether or not the set value stored in the atrioventricular delay set value storage means 41 has been exceeded. (Step S71). If it is determined in the determination step S71 that a time-out has occurred, an output is issued from the atrioventricular delay comparison means 42 to the ventricular stimulation means 3, and ventricular stimulation is performed (step S72). When this ventricular stimulation is performed, and after the time measurement of the atrioventricular delay timer 40 is stopped in step S70, the ventricular pressure (sixth embodiment) and the precursor ejection time (seventh time) are detected by the sensor means of each embodiment. And the stroke volume (eighth embodiment) are detected (step S73). Then, the physiological quantity related to exercise and mental stress detected by the sensor means of each embodiment is sent to the nerve stimulation parameter table storage means 31, and the optimal nerve stimulation parameter corresponding to the patient is selected (step S74). ). The selection of the nerve stimulation parameter here includes selection of whether or not to perform nerve stimulation. When nerve stimulation is performed, the nerve stimulation flag is turned on.
[0090]
As described above, a plurality of embodiments of the heart treatment device of the present invention have been described on the basis of block diagrams and flow diagrams. It is possible to detect biological information and control nerve stimulation parameters.
[0091]
【The invention's effect】
As described above, according to the present invention, the excitement level of a patient's sympathetic nerve due to exercise and stress can be known from various biological information, and the vagus nerve can be stimulated appropriately and finely according to the excitement level. For this reason, significant effects such as avoiding side effects caused by nerve stimulation and excessive reduction in heart rate and saving power consumption can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration example of first and second embodiments of a heart treatment device of the present invention.
FIG. 2 is an arrangement view of an electrode lead and a stimulation electrode used in the heart treatment device of the present invention on the heart.
FIG. 3 is a configuration diagram of sensor means for detecting a QT time in the first embodiment of the heart treatment device of the present invention.
FIG. 4A is a waveform diagram showing an intracardiac electrogram and QT time of the heart, and B is a waveform diagram obtained by integrating the intracardiac electrogram.
FIG. 5 is a flowchart showing the operation of the first embodiment of the heart treatment device of the present invention using a QT time detection sensor as the sensor means of the block diagram of FIG. 1;
FIG. 6 is a configuration diagram of an electrocardiogram area sensor for detecting an electrocardiogram area used in the second embodiment of the heart treatment device of the present invention.
FIG. 7 is a flowchart showing the operation of the second embodiment of the heart treatment device of the present invention using an electrocardiogram area sensor as the sensor means of the block diagram of FIG. 1;
FIG. 8 is a block diagram showing a configuration example of a third embodiment of the heart treatment device of the present invention.
FIG. 9 is a block diagram showing a configuration example of a fourth embodiment of the heart treatment device of the present invention.
FIG. 10 is a block diagram showing a configuration example of a fifth embodiment of the heart treatment apparatus of the present invention.
FIG. 11 is a flowchart showing the operation of the third to fifth embodiments of the heart treatment device of the present invention shown in FIGS. 8 to 10;
FIG. 12 is a block diagram showing a configuration example of a sixth embodiment of the heart treatment device of the present invention.
FIG. 13 is a block diagram showing a configuration example common to the seventh to eighth embodiments of the heart treatment device of the present invention.
FIG. 14 is a configuration diagram of a ventricular precursor time sensor used in a seventh embodiment of the heart treatment device of the present invention.
FIG. 15 is a block diagram of a stroke volume sensor used in an eighth embodiment of the heart treatment device of the present invention.
FIG. 16 is a flowchart for explaining the operation of the sixth to eighth embodiments of the heart treatment device of the present invention shown in FIGS. 12 to 15;
FIG. 17A is a diagram showing the structure of the heart, and B is an example of an electrocardiogram measured by placing electrodes on the body surface.
FIG. 18 is a diagram illustrating nerve stimulation parameters.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Heart treatment apparatus, 2 ... Control means, 3 ... Ventricular stimulation means, 4 ... Ventricular contraction detection means, 5 ... Atrial stimulation means, 6 ... Atrial contraction detection means, 7 ... nerve stimulation means, 8 ... sensor means, 9 ... ventricular electrode lead, 10 ... ventricular stimulation / detection electrode, 11 ... atrial electrode lead, 12 ... atrial stimulation / detection electrode, DESCRIPTION OF SYMBOLS 13 ... Heart, 16 ... Neural electrode lead, 17 ... Neural stimulation electrode, 18 ... Vagus nerve, 43 ... Body motion sensor, 44 ... Blood sensor, 50 ... Respiration sensor 61 ... Ventricular contractile ventricular pressure sensor, 71 ... Ventricular precursor sensor, 75 ... Stroke volume sensor

Claims (9)

A nerve stimulation means for generating a nerve stimulation signal for stimulating the vagus nerve,
A cardiac stimulation means for generating cardiac stimulation pulses for stimulating the heart;
Sensor means for sensing biological information that changes due to exercise or mental stress ;
Control means connected to the nerve stimulation means and the sensor means;
The control means, when it is determined from the output of the sensor means that the degree of excitement of the sympathetic nerve is intense, the nerve stimulation signal so as to perform stronger nerve stimulation than when it is determined that the degree of excitement is small. Adjusting a parameter of the heart.   The parameter of the neural stimulation signal is at least one of a period between pulses, a pulse width, a pulse number, a pulse current, a pulse voltage, a delay time, a pause time, and the number of repetitions, or a plurality of combinations selected from these. The heart treatment apparatus according to claim 1.   The heart treatment apparatus according to claim 1, wherein the sensor means detects a contractility of the ventricle.   The cardiac treatment device according to claim 3, wherein the contractility of the ventricle is any one of QT time, electrocardiogram area, precursor delivery time, stroke volume, and ventricular pressure.   The heart treatment device according to claim 3 or 4, wherein the nerve stimulation means stops the generation of the nerve stimulation signal when the contractility of the ventricle is smaller than a predetermined threshold value.   The heart treatment apparatus according to claim 1, wherein the sensor means senses body movement.   The heart treatment device according to claim 1 or 2, wherein the sensor means senses respiration.   The heart treatment device according to claim 1 or 2, wherein the sensor means senses blood. Cardiac contraction detection means for detecting cardiac contraction, wherein the cardiac stimulation means stimulates the heart at a predetermined rate and cancels generation of cardiac stimulation pulses in response to the cardiac contraction detection means The heart treatment device according to any one of claims 1 to 8, wherein the lower limit of the heart rate is maintained.

Images