JP2011005008A - Heart treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a side effect on a vagus nerve due to stimulation and to achieve miniaturization and reduction of power consumption while accurately detecting heartbeats.SOLUTION: This heart treatment device 1 includes: a heartbeat detecting part 2 that detects heartbeats by using an electrode disposed at the heart A; a pulse transformer 5 having a primary winding 5a and a secondary winding 5b connected to the vagus nerve B, the heartbeat detecting part 2 being disposed on the side of the primary winding 5a; and a pulse generating part 8 that supplies an electric pulse to the primary winding 5a of the pulse transformer 5 based on the heartbeats detected by the heartbeat detecting part 2, the electric pulse having a pulse width not exceeding the ET (voltage-time) product of the pulse transformer 5.

Description

  The present invention relates to a heart treatment device.

  2. Description of the Related Art Conventionally, heart treatment apparatuses that perform defibrillation by electrically stimulating the vagus nerve during cardiac fibrillation or tachycardia are known (see, for example, Patent Documents 1 to 3).

JP-A-8-38625 JP 2004-173790 A JP 2009-28397 A

  However, the electric pulse having a pulse width of 0.1 to several msec, which is used for vagus nerve stimulation in Patent Document 1, may cause side effects on the vagus nerve, and the use of an electric pulse with lower energy is desired. . Further, in Patent Documents 1 and 2, there is a problem that the electric pulse supplied to the vagus nerve wraps around the heartbeat detection circuit and the heartbeat cannot be accurately detected during stimulation of the vagus nerve. In order to solve this problem, in Patent Document 3, the vagus nerve stimulation unit that outputs an electric pulse to the vagus nerve is electrically insulated from the heartbeat detecting unit, thereby preventing the electric pulse from entering the heartbeat detecting unit. is doing. However, power supply sources are provided in areas that are insulated from each other, which disadvantageously increases the size and power consumption of the heart treatment device.

  The present invention has been made in view of the above-described circumstances, and prevents cardiac side effects caused by stimulation, and can reduce the size and power consumption while accurately detecting the heartbeat. The object is to provide a device.

In order to achieve the above object, the present invention provides the following means.
The present invention provides a heartbeat detection unit that detects a heartbeat by means of an electrode disposed on a heart, a pulse transformer in which the heartbeat detection unit is disposed on a primary winding side, and a secondary winding is connected to a vagus nerve, Provided is a heart treatment device comprising: a pulse generation unit that supplies an electric pulse having a pulse width not exceeding an ET product of the pulse transformer to a primary winding of the pulse transformer based on the heartbeat detected by the heartbeat detection unit To do.

According to the present invention, when the heart rate rises and the time interval of the heartbeat detected by the heartbeat detection unit is shortened, an electric pulse is supplied from the pulse generation unit to the vagus nerve via the pulse transformer to stimulate the vagus nerve. Thus, the heart rate can be lowered and stabilized.
In this case, since an electric pulse having a sufficiently short pulse width, which is limited by the ET product of the pulse transformer, is supplied to the vagus nerve, side effects on the vagus nerve due to stimulation can be prevented.

  In addition, since the heartbeat detection unit and the vagus nerve are electrically insulated by the pulse transformer, the wraparound of the electric pulse supplied to the vagus nerve to the heartbeat detection unit is prevented, and even during stimulation of the vagus nerve Heartbeat can be detected accurately. Further, by supplying power from the primary winding side of the pulse transformer to the secondary winding side, a power supply source may be provided only on the primary winding side of the pulse transformer. Thereby, size reduction of a heart treatment apparatus and reduction of power consumption can be aimed at.

  In the above invention, the power supply unit is disposed on the primary winding side of the pulse transformer and supplies power to the pulse generation unit, and the pulse transformer includes the secondary winding with respect to the primary winding. The winding ratio may be larger than the ratio of the voltage of the electric pulse to the voltage of power supplied by the power supply unit.

  In this way, the electric pulse output from the pulse generator is boosted from the voltage of the power supply unit by the pulse transformer and supplied to the vagus nerve. As a result, the configuration for boosting the voltage of the electric pulse such as a booster circuit is not required, and the heart treatment device can be further downsized and the power consumption can be further reduced.

  Further, in the above invention, a plurality of the pulse transformers are provided, and the pulse generation unit continuously generates the electric pulse, and is disposed between each pulse transformer and the vagus nerve, and the vagus nerve A rectifier circuit that limits a current from the pulse generator to each of the pulse transformers, and a transformer selection that selects a pulse transformer to which the electric pulses are supplied from the pulse generator so that successive electric pulses are supplied to different pulse transformers It is good also as providing a means.

  In this way, even if the pulse width of each electric pulse is short and insufficient for stimulation of the vagus nerve, the electric pulse is continuously supplied to the vagus nerve from a plurality of pulse transformers to the vagus nerve. A sufficiently long pulse width can be obtained as the whole supplied electric pulse. The rectifier circuit can prevent an unintended pulse transformer from being a load. In addition, the electrical pulse supplied from one pulse transformer to the vagus nerve can be prevented from flowing into other pulse transformers via the vagus nerve, and the electrical pulse can be more reliably prevented from entering the heartbeat detection circuit. it can.

Moreover, in the said invention, the said pulse generation part is good also as generating the electric pulse from which a voltage differs.
In this way, by combining electrical pulses with different voltages, the overall shape of the electrical pulse supplied to the vagus nerve is formed into a shape more suitable for stimulation of the vagus nerve, thereby improving the therapeutic effect. Can do.

  ADVANTAGE OF THE INVENTION According to this invention, the side effect to the vagus nerve by a stimulus is prevented, and there exists an effect that size reduction and reduction of power consumption can be aimed at, detecting a heartbeat correctly.

1 is an overall configuration diagram of a heart treatment device according to an embodiment of the present invention. It is a figure which shows the stimulation pulse in (a) point a of FIG. 1, and (b) point b. It is a flowchart explaining operation | movement of the heart treatment apparatus of FIG. It is a figure which shows the modification of the heart treatment apparatus of FIG. It is a figure which shows the stimulation pulse in (a) point a of FIG. 3, (b) b point, and (c) c point. It is a flowchart explaining operation | movement of the vagus nerve stimulation part of the heart treatment apparatus of FIG. It is a figure which shows the modification of the stimulation pulse in (a) point a of FIG. 3, (b) b point, and (c) c point.

A heart treatment apparatus 1 according to an embodiment of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, the heart treatment device 1 according to the present embodiment includes a heartbeat detection circuit (heartbeat detection unit) 2 that detects a heartbeat, and a defibrillation that supplies a defibrillation pulse and a pacing pulse to the heart A, respectively. Motion pulse generator 3 and pacing pulse generator 4, vagus nerve stimulator 6 including pulse transformer 5 connected to vagus nerve B, defibrillation pulse generator 3, pacing pulse generator 4 and vagus nerve stimulator 6 and a control unit 7 for controlling 6.
The heartbeat detection circuit 2 detects a heartbeat based on a waveform of an electrocardiogram signal obtained from a potential change of an electrode arranged in the heart A.

  The defibrillation pulse generator 3 and the pacing pulse generator 4 are defibrillated by instantly discharging electric charge from a charged capacitor (not shown) to the heart A in the same manner as the configuration of a conventional heart treatment device. Pulses or pacing pulses are generated. The defibrillation pulse generator 3 uses a defibrillation electrode (not shown) connected to the heart A when defibrillation occurs in the heart A. Deliver fibrillation pulses to heart A. The pacing pulse generation unit 4 uses a pacing pulse common to the heartbeat detection circuit 2 when a bradycardia occurs in the heart A. Supply to heart A through electrodes.

  The vagus nerve stimulation unit 6 includes a DA converter (pulse generation unit) 8 to which a digital signal is input from the control unit 7, a primary winding 5a connected to the DA converter 8, and a secondary winding 5b connected to the vagus nerve. And a pulse transformer 5 connected to B. When the digital signal is input from the control unit 7 to the DA converter 8, the DA converter 8 converts the digital signal into a square wave analog signal, that is, a stimulation pulse (electrical pulse), and the converted signal is applied to the primary winding 5 a of the pulse transformer 5. Entered. Thereby, the stimulation pulse can be supplied to the vagus nerve B connected to the secondary winding 5b of the pulse transformer 5 to stimulate the vagus nerve B. At this time, the DA converter 8 outputs a stimulation pulse having a voltage substantially the same as the voltage of the battery 9 included in the heart treatment device 1.

  In general, the pulse transformer 5 has a larger dimension as the ET product is larger, and an outer diameter dimension suitable for implantation in a living body is selected. Further, the pulse transformer 5 is selected in accordance with the voltage of the stimulation pulse to be supplied to the vagus nerve B, and the winding ratio between the primary winding 5a and the secondary winding 5b is suitable.

  For example, it is assumed that a battery 9 having a voltage of 3V and a pulse transformer 5 having an ET product of 3V · μs, which are generally used in an implantable heart treatment apparatus, are used. In this case, if the voltage of the stimulation pulse supplied to the primary winding 5a of the pulse transformer 5 is 3V, the upper limit of the pulse width at that time is about 1 μs. The pulse transformer 5 is assumed to have a winding ratio of 1: 3 between the primary winding 5a and the secondary winding 5b. Thereby, the voltage of the stimulation pulse at the point b in FIG. 1 is 3 times the voltage of the stimulation pulse at the point a in FIG. 1, that is, 9 V, as shown by the solid lines in FIGS. The pressure is increased.

  The control unit 7 monitors the time interval T of heartbeats sequentially detected by the heartbeat detection circuit 2. Then, the control unit 7 reduces the tachycardia when the heartbeat time interval T is smaller than the first predetermined lower limit T1, and reduces the tachycardia when the heartbeat time interval T is smaller than the second predetermined lower limit T2, which is smaller than the first predetermined lower limit. The bradycardia is determined when the movement is greater than the predetermined upper limit T3. When the controller 7 determines the abnormality, the controller 7 causes the defibrillation pulse generator 3 or the pacing pulse generator 4 to output a defibrillation pulse or pacing pulse based on the determination, or causes the DA converter 8 to output the defibrillation pulse or pacing pulse. Output a digital signal.

The operation and action of the thus configured heart treatment device 1 will be described below with reference to FIG.
When the heart treatment device 1 according to the present embodiment starts detecting heartbeats (step S1), the heartbeat time interval T is constantly monitored (step S2). When the heart A fibrillates and the heartbeat time interval T falls below the second predetermined lower limit T2 (step S3), a defibrillation pulse is supplied to the heart A (step S4), and defibrillation is performed. .

  When the heart A has a tachycardia and the heartbeat time interval T falls below the first predetermined lower limit T1 (step S5), a stimulation pulse is output to the vagus nerve B (step S6), and the heart rate is in the normal range. Can be lowered. When the heart A causes bradycardia and the heartbeat time interval T exceeds a predetermined upper limit T3 (step S7), a pacing pulse is output to the heart A (step S8), and the heartbeat is raised to the normal range.

  In this case, according to the present embodiment, the heartbeat detection circuit 2 and the vagus nerve B are arranged on the different windings 5a and 5b side of the pulse transformer 5 and are electrically insulated from each other, while the pulse transformer 5 1 The stimulation pulse generated on the side of the next winding 5a is transmitted to the vagus nerve B. This prevents the stimulation pulse from wrapping around the heartbeat detection circuit 2 and has an advantage that the heartbeat can be accurately detected even while the vagus nerve B is being stimulated. Further, since only one power supply source is required, there is an advantage that the power consumption and size of the heart treatment device 1 can be reduced.

  In addition, the stimulation pulse generated on the primary winding 5a side of the pulse transformer 5 is boosted by the pulse transformer 5 from the voltage of the battery 9 to a voltage suitable for stimulation of the vagus nerve B, and therefore generated by the DA converter 8. A booster circuit or the like for boosting the stimulated pulse is not required. Thereby, there exists an advantage that the reduction in power consumption and size reduction of the heart treatment apparatus 1 can further be achieved. Further, there is an advantage that side effects on the vagus nerve B can be prevented by using a stimulation pulse whose pulse width is sufficiently shorter than the pulse width of the electric pulse conventionally used for stimulation of the vagus nerve B.

In the above embodiment, the stimulation pulse may be supplied to the vagus nerve B in a burst shape.
For example, as indicated by the chain line in FIGS. 2A and 2B, the stimulation pulse is output a plurality of times with a time interval similar to the pulse width of each stimulation pulse. Thereby, the vagus nerve B can be stimulated more strongly and tachycardia can be stopped more effectively.

In the above embodiment, the stimulation pulse is supplied to the vagus nerve B using one pulse transformer 5. Instead, the stimulation pulse is continuously vagus using a plurality of pulse transformers 5. It is good also as supplying to the nerve B.
When the small pulse transformer 5 is used, the ET product thereof is relatively low, so that the pulse width of the stimulation pulse that can be supplied to one pulse transformer 5 at a time is limited to be relatively short. Therefore, as illustrated above, according to the design based on the configuration of the conventional heart treatment device, the pulse width actually used in the heart treatment device 1 of the present embodiment is about 1 μs.

  For example, as shown in FIG. 4, when two DA converters 8 and a pulse transformer 5 are used, digital signals continuously output from the control unit (transformer selection means) 7 are alternately sent to the DA converters 8. To enter. Thereby, as shown in FIGS. 5A and 5B, stimulation pulses are alternately generated at points a and b in FIG. These stimulation pulses can be regarded as one stimulation pulse having an expanded pulse width at the point c in FIG. 3, as shown in FIG. 5 (c). That is, a stimulation pulse whose energy is increased by expanding the pulse width is supplied to the vagus nerve B.

  In this case, a rectifier circuit 10 such as a diode is provided at the subsequent stage of each pulse transformer 5 in order to prevent an unintended pulse transformer 5 from being a load of the stimulation pulse output from the DA converter 8. This also prevents the stimulation pulse supplied from one pulse transformer 5 to the vagus nerve B from flowing in the reverse direction to the other pulse truss 5 via the vagus nerve B.

The operation of the vagus nerve stimulation unit 6 configured as described above will be described below with reference to FIG. The pulse width X indicates the pulse width of each stimulation pulse, and the pulse width Y indicates the entire pulse width of the plurality of stimulation pulses to be supplied to the vagus nerve B.
When tachycardia is determined by the control unit 7, the vagus nerve stimulation unit 6 sets the output voltage of the DA converter 8 according to the specification of the stimulation pulse determined by the control unit 7 (step S11) (step S11). In addition, the pulse width X of the stimulation pulse limited by the output voltage and the ET product of the pulse transformer 5 is determined (step S13). And the variable Z with respect to the sum total of the pulse width of the stimulation pulse supplied to the vagus nerve B is set to the pulse width Y (step S14), and one DA converter 8 is selected (step S15).

  If the variable Z is larger than the pulse width X (step S16), the stimulation pulse having the pulse width X is output (step S17), the output pulse width X is subtracted from the variable Z (step S18), and DA conversion is performed. The output of the stimulation pulse having the pulse width X is repeated while switching the device 8 to the other (step SS19). When the variable Z becomes smaller than the pulse width X (step S16), a stimulation pulse having a pulse width Z is output (step S20). As a result, a stimulation pulse having a pulse width Y as a whole is supplied to the vagus nerve B.

  In this manner, the supply of the stimulation pulse having the pulse width Y to the vagus nerve B is repeated a predetermined number of times (step S23) while incrementing the counter (step S22) at a predetermined time period (step S21). When the stimulation over the set duration is completed, whether or not the tachycardia is stopped by the control unit 7 monitoring the heartbeat for a certain period, for example, a time obtained by subtracting the duration from 60 seconds (step S24). Determined.

By doing in this way, even if the energy of each stimulation pulse output from the pulse transformer 5 is insufficient for the stimulation of the vagus nerve B, the energy of the stimulation pulse can be appropriately increased.
In this case, a stimulation pulse may be supplied from each DA converter 8 to each pulse transformer 5 while alternately switching the path by a switch or the like. By doing in this way, the structure of the heart treatment apparatus 1 can be simplified further and size reduction can be achieved.

When a plurality of pulse transformers 5 are used, the voltage of each stimulation pulse input to each pulse transformer 5 may be changed.
For example, as shown in FIGS. 7A and 7B, when a stimulation pulse is alternately input to each pulse transformer 5 while raising and lowering the voltage, as shown in FIG. Is approximately formed as a triangular wave as a whole. By doing in this way, the stimulation pulse supplied to the vagus nerve B is formed not only in the square wave but in various shapes, and by using the stimulation pulse having a shape suitable for treatment, the therapeutic effect of the heart treatment device 1 is achieved. Can be improved.

1 heart treatment device 2 heart rate detection circuit (heart rate detection unit)
DESCRIPTION OF SYMBOLS 3 Defibrillation pulse generation part 4 Pacing pulse generation part 5 Pulse transformer 5a Primary winding 5b Secondary winding 6 Vagus nerve stimulation part 7 Control part (transformer selection means)
8 DA converter (pulse generator)
9 Battery (Power supply unit)
10 Rectifier circuit A Heart B Vagus nerve

Claims (4)

A heart rate detection unit for detecting a heart rate by means of an electrode disposed on the heart;
A pulse transformer in which the heartbeat detection unit is arranged on the primary winding side, and the secondary winding is connected to the vagus nerve;
A heart treatment apparatus comprising: a pulse generation unit that supplies an electric pulse having a pulse width not exceeding an ET product of the pulse transformer to a primary winding of the pulse transformer based on the heartbeat detected by the heartbeat detection unit. A power supply unit disposed on the primary winding side of the pulse transformer, for supplying power to the pulse generation unit;
2. The heart according to claim 1, wherein the pulse transformer has a winding ratio of the secondary winding to the primary winding larger than a ratio of the voltage of the electric pulse to the voltage of power supplied by the power supply unit. Therapeutic device. A plurality of the pulse transformers are provided,
The pulse generator continuously generates the electrical pulses;
A rectifier circuit that is arranged between each pulse transformer and the vagus nerve and limits a current from the vagus nerve to each pulse transformer;
The heart treatment device according to claim 1, further comprising: a transformer selection unit that selects a pulse transformer to which the electric pulse is supplied by the pulse generation unit so that the continuous electric pulse is supplied to different pulse transformers.   The heart treatment device according to claim 3, wherein the pulse generator generates electrical pulses having different voltages.

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