JP4548824B2 - Active implantable medical devices such as AAI or AAI / DDD type pacemakers, defibrillators and / or cardioverter defibrillators - Google Patents

Description

  The present invention relates to an “active implantable medical device” as defined in EC Council No. 90/385 / CEE dated June 20, 1990, and more specifically, to treat the heart to treat cardiac arrhythmias. Pacemaker devices capable of delivering low energy electrical stimulation to the device, “multi-site” devices (ie devices capable of pacing in 3 or 4 cardiac sinuses), defibrillators and / or cardio The present invention relates to a device such as a fibrillation device. More specifically, including stimulation and detection circuitry on the atrium and ventricle, operating according to two pacing modes, DDD or AAI (AAI mode is a DDD mode with prolonged atrial-ventricular delay) it can. Optionally, the device may include a mode called “automatic mode switching” that achieves automatic switching between DDD mode and AAI mode based on meeting a preset requirement to allow mode switching.

  However, as will be appreciated by those skilled in the art, the present invention is not limited to devices having automatic mode switching and is equally applicable to devices configured to operate only in AAI mode, In configuration, the present invention proposes to modify the AAI operating mode without having automatic mode switching and / or to avoid automatic mode switching.

  The basic mode of operation of a DDD / AAI cardiac pacemaker is the AAI mode with single sinus chamber atrial stimulation and monitoring (detection) of ventricular activity. This mode is maintained as long as atrioventricular conduction is normal, i.e., as long as the ventricular detection corresponding to each atrial event (atrial detection corresponding to spontaneous activity, or ventricular stimulation corresponding to a paced event) follows. Is done. In certain circumstances, there is an atrial-ventricular block (AVB) that includes temporary ventricular polarization disturbances. In this case, the cardiac pacemaker automatically switches to operate in the DDD mode with parameters optimized for the temporary AVB situation. After AVB disappears and spontaneous atrioventricular conduction is re-established and after a certain number of states have been implemented, the cardiac pacemaker automatically switches to operate in AAI mode. This automatic mode switching between DDD and AAI modes is described, for example, in EP-A-0488904 and its corresponding U.S. Pat. No. 5,318,594, which is processed as usual and is an ELA in Montrouge, France. Granted to Medical.

  The starting point of the present invention is that the inventors made observations when a patient developed ventricular extrasystole (VES) during clinical follow-up of a patient wearing a DDD / AAI device with AAI or automatic mode switching. That is. VES is a spontaneous ventricular event that exhibits a significant ventricular interval PR (or VR) compared to a slightly preceding ventricular event with a preceding associated atrial depolarization. Due to VES binding compared to previous ventricular events, VES occurs simultaneously with atrial depolarization of subsequent heartbeats (ie, cardiac cycle) or is detected in the instant near the end of the atrial supplementary contraction interval (AEI), ie, within the atrium. Occurs at the moment when a spontaneous event is lacking and an atrial stimulus needs to be applied.

In some cases described in detail below, known devices have limited ability to properly detect or manage electrocardiographic activity when a VES occurs at a particular critical heart wave moment. Is shown. Due to the lack of the ability to properly manage all the situations that can occur when a VES occurs:
1. Inappropriate atrial or ventricular stimulation is applied to the heart and is therefore ineffective and possibly problematic for blood flow;
2. With these AAI / DDD devices with automatic mode switching, DDD mode with wrong interatrioventricular block diagnosis (misidentified that the device detected AVB when spontaneous conduction actually exists) Switching occurs;
3. A combination of the above two malfunctions, i.e. improper stimulation followed by a switch to unwanted DDD mode,
It is triggered. These inadequate effects lead to the patient's specific disease state, which is likely to lead to the occurrence of ventricular velocity / rhythm disorders and must be prevented.

Subject and summary of invention

Accordingly, the present invention provides active implantable medical devices such as pacemakers, defibrillators and / or cardioverter defibrillators:
Means for detecting spontaneous atrial and ventricular events, including means for detecting the occurrence of premature ventricular contractions during spontaneous ventricular events;
Counted when means for calculating an atrial supplementary contraction interval and means for initiating counting of the supplementary contraction interval calculated in response to detection of an atrial event and when no spontaneous atrial event has been detected during this interval Means for applying atrial stimulation at the end of an atrial replenishment contraction interval;
And to an improved device and process comprising:

According to the invention, said device further comprises:
Means for defining a critical period in relation to the end of the counted atrial supplementary systolic interval;
Means for determining whether the instant of occurrence of ventricular extrasystole is during the critical period when a ventricular extrasystole is detected;
Means for recognizing the occurrence of a dangerous condition, said dangerous condition being based on the vicinity of the end of the ventricular extrasystole and the end of the atrial supplementary contraction interval, corresponding to improper operation and / or a wrong diagnosis, Means for changing the operating parameter of at least one device in response to detecting that an extrasystole has occurred within the critical period to eliminate the dangerous condition;

The aforementioned critical period can precede or follow the end of the counted atrial supplementary contraction interval, and more preferably:
1. A period defined by a time window that precedes the end of the atrial replenishment contraction interval with a preset time interval, eg, precedes the end of the atrial replenishment contraction interval with less than about 63 ms;
2. A post-ventricular atrial refractory period (PVARP) following the end of the atrial replacement systole interval, in which counting is initiated in response to detection of premature ventricular contractions;
3. A monitoring period for inter-chamber interference following the end of the atrial replenishment contraction interval, wherein a count is initiated in response to the application of an atrial stimulation pulse at the end of the atrial replenishment contraction interval;
4). A post-atrial stimulation blanking period following the end of the atrial replenishment contraction interval, the count being initiated in response to the application of an atrial stimulation pulse at the end of the atrial replenishment contraction interval;
It is preferable to do.

  For the first and second critical phase examples, the means for changing the operating parameters of the at least one device is notably a count of atrial replenishment systolic intervals in response to detection of preventricular contraction (VES). It can be a reset (ie, the start of a new atrial replacement contraction interval). The present invention is adapted in this respect to the "automatic mode switching" type device described above, i.e. means for stimulating the ventricle; means for diagnosing atrioventricular block; not followed by a correlated spontaneous ventricular event Means for detecting the occurrence and repetition of spontaneous or stimulated atrial events; and mode switching means capable of controlling switching from AAI mode to DDD mode in response to proven atrioventricular block diagnosis; Is characterized in that the at least one operating parameter changing means includes means for prohibiting the mode switching means from switching modes.

  For the second and fourth critical phase examples, the means for changing at least one operating parameter of the device includes the last detected atrial event and ventricular extrasystole, particularly in response to the occurrence of a ventricular extrasystole. Measuring the time lapse between the time of occurrence of (i) if the measured time lapse is within a given time interval that is shorter than the calculated duration of the atrial replacement contraction interval; and / or Or (ii) setting an indicator of suspected misdiagnosis when ventricular stimulation is added within the safety window following the addition of atrial stimulation; (a) at least one not followed by a correlated spontaneous ventricular event Detecting one atrial stimulus and / or (b) responding to the alleged misdiagnosed indicator being set to a first preset number of cycles, eg 12 cycles. It is possible to prohibit the switching. The preset time interval is, for example, in the range of 10 to 120 ms, and can be preferably 63 ms shorter than the atrial replacement contraction interval. The suspicion indicator may have a set state (eg, logic 1) corresponding to the presence of suspicion and a reset state (eg, logic 0) corresponding to the absence of suspicion. In this regard, the misdiagnosed suspicion indicator is responsive to a second preset number of cycles, eg, no atrial event not being followed by a correlated spontaneous ventricular event for 12 cycles. Can be reset (ie there is no suspicion).

  For the second, third, and fourth critical phase examples, the means for changing at least one operating parameter of the device includes the last detected atrial event, particularly in response to the occurrence of a premature ventricular contraction. Measure the time course between the occurrence of a premature ventricular contraction; (i) the measured time course is located within a given time interval that is less than the calculated duration of the atrial replacement contraction interval And / or (ii) the atrial replacement contraction interval can be extended by a preset duration in response to the ventricular stimulus being applied within the safety window following the application of the atrial stimulus. The extension time of the preset atrial supplementary contraction interval is, for example, 10 to 120 ms, preferably 63 ms. The prolonged atrial replacement interval was calculated by the atrial stimulator in response to no atrial stimulation being detected for a preset number of cycles, for example 12 cycles, for which there is no correlated spontaneous ventricular event. It can be restored to its initial value.

  Other details, characteristics and various advantages of the present invention will be understood by those skilled in the art by means of preferred embodiments which will be described in detail below with reference to the accompanying drawings.

Detailed Description of the Invention

  The present invention can be implemented by any known circuit technique, and more preferably, the control software of a known two-sinus ventricular type pacemaker that combines the DDD mode and the AAI mode with monitoring of ventricular activity is suitably used. Implemented by programming. However, as described above and as described below, the present invention is applied to a cardiac pacemaker that functions only in the AAI mode by adjusting the execution condition of the AAI mode and reflecting it in the software command. You can also.

The following definitions are used repeatedly in the description.
P-wave detection or DetP; sensing of spontaneous activity originating from the atria; if a P-wave is detected if no ventricular detection follows within a given delay period, eg about 31 ms for this detection Possible (otherwise sensing “far field far field”, ie remote depolarization coming from the ventricle within the atrium).
R-wave detection or DetR; sensing of spontaneous activity originating from the ventricle.
Stimulus A or StimA; a stimulus applied to the atria.
Stimulus V or StimV; a stimulus applied to the ventricle.
Atrial event; P-wave detection or stimulation A.
Ventricular event; R-wave detection or stimulation V.
Cardiac cycle; the interval separating two comparable events in the same sinus chamber, for example two P-wave detections or two stimuli A.
Average PP; for example, the average interval between atrial velocities calculated over 8 cycles not including extrasystoles.
Atrial supplementary contraction interval (AEI): A time interval counted after P wave detection or stimulation A in the atrium. If no P wave is detected in the same sinus chamber, stimulation A is added subsequently.
Ventricular extrasystole (VES); ventricular detection is preceded by ventricular R-wave detection or stimulation V and the ventricular event coupling interval (RR or VR) is, for example, 75% or less of the average RR VES.

  For further details regarding the detection and treatment of extrasystoles, reference may be made to EP 0550342 and the corresponding US Pat. No. 5,31,451 to ELA Medical, which are generally It is incorporated herein.

In the context of the present invention, the cardiac pacemaker operates in conventional AAI mode while monitoring ventricular activity, i.e., atrial detection outside the refractory period (P wave detection) or atrial stimulation (stimulus A) does not initiate AVD, rather The atrial supplementary contraction interval AEI is started. For AAI mode with monitoring of ventricular activity, the algorithm can additionally search for the presence or absence of ventricular events and give permission for suspicion of AVB if a ventricular event is present, and therefore inter-atrioventricular relationship if necessary That is, switch to the two-chamber chamber DDD mode with AVD calculation and application. Three situations can trigger the DDD mode:
1. A complete atrioventricular block, a condition indicated by a “blocked” atrial wave (stimulated or spontaneous), ie an atrial depolarization that is not followed by a ventricular depolarization. In particular, mode switching intervenes when two blocked waves that are detected or stimulated are consecutive, or when ventricular detection is not performed for longer than 3 seconds.
2. A secondary atrioventricular block (AVBII), which is a condition that occurs when the ratio of the number of P waves that are not extra systolic divided by the number of R waves that are not extra systolic is greater than one. Mode switching intervenes when the device detects a ratio of typically 12/9 or higher.
3. Primary atrioventricular block (AVBI), a condition indicated by an atrioventricular conduction delay greater than a given value, particularly 350 ms after a spontaneous P wave or 450 ms after a stimulated P wave. Switching to the DDD mode intervenes after n consecutive cycles, preferably n is 6.

  If one of these requirements exists, the device automatically switches from AAI mode to DDD mode.

  After returning to a predetermined number of spontaneous ventricular activities, or after being in DDD mode for a preset number of cycles, the device automatically switches from DDD mode to AAI mode, and the three AAI The AAI mode is maintained unless any of the switching requirements from the mode to the DDD mode is satisfied.

  As the inventors have recognized, the above-described clinical trials ensure that the operation during conventional AAI mode and / or AAI / DDD automatic mode switching is properly performed by generating VES during the critical period of a specific heart rhythm. Several cases that did not work were observed.

The first case is shown in FIG. 1a, where atrial detection P ₂ (FIG. 1a) precedes extra systolic ventricular depolarization (VES) with a small time, particularly less than 30 ms. According to known devices, the device is (1) intrinsic spontaneous atrial depolarization and (2) “far field” ventricular detection situation, ie after a certain delay rather than due to atrial depolarization hear "VES detection due to the inability to distinguish between a situation in which signals detected in the atrium derived from the atrial detection P ₂ is disabled by the detection algorithm and cardiac rhythm analysis. If there is a suspicion, the device assumes that there is no P-wave, and therefore does not regenerate (i.e., restart counting) according to AAI mode (pure AEI mode is a mode with no ventricular slip detection). At the end of the atrial escape interval AEI, for spontaneous atrial detection by a subsequent P ₁ wave it is not confirmed and activate a cardiac pacemaker adds the atrial stimulation to induce atrial depolarization A _1. Compared to the previous spontaneous atrial depolarization P ₂ disabled by the rate analysis algorithm, this stimulated atrial depolarization A ₁ is premature and if it occurs during the atrial fragility period, the atrial rate There is a danger of inducing disability.

In addition, if this stimulation induced an effective atrial depolarization, i.e. even itself induced ventricular depolarization R _{2 (FIG.} 1a), which ventricular event preceded, i.e. premature contraction of events VES Compared to the early departure. This type of condition is known as creating a ventricular velocity / rhythm disorder.

The solution proposed by the present invention, shown in FIG. 1b, relates to AEI regeneration in response to VES detection. The regeneration of AEI in response to this ventricular event has an effect similar to that produced by a spontaneous atrial event. The new interval AEI ^* delays the application of atrial stimulation pulses in time in the absence of spontaneous depolarization A ₁ ^* (FIG. 1b). Compared to P ₂ waves, the maximum error to be induced by the reproduction of the AEI to respond to ventricular event VES corresponds to the case where spontaneous reputation event occurs at the end of the refractory period after VES, which is physiologically acceptable It is possible (ie the maximum delay of stimulation is equal to the duration of the refractory period). Conversely, if the VES is very early, the replay of this ventricular event is not important, as the subsequent atrial depolarization that occurs after the end of the post-VES refractory period regenerates the AEI and this is expected in the AAI mode This is because it corresponds to the operation.

The second case is shown in Figure 2a, it occurs when the atrial depolarization P ₂ intervenes shortly after rather than before the VES detecting. In this case, atrial depolarization is not detected by the device because it occurs during the post ventricular atrial refractory period (PVARP). The atrial depolarization P ₂ is not considered, AEI atrial stimulus is added to the end of the AEI follow not play, unnecessary atrial depolarization A ₁ is triggered. Atrial stimulation A ₁ is earlier than hidden atrial depolarization P ₂ and therefore does not induce ventricular depolarization that correlates with natural conduction. Thus, the cardiac pacemaker detects a configuration having an atrial stimulus that is not followed by ventricular depolarization, i.e., an AVB stimulus. If this continuation continues three times out of twelve times, the device automatically switches to the DDD mode in an appropriate manner.

  As is known, this second case leads to two problems. One is the same blood flow problem as in the first case by intervening at the moment when atrial stimulation is inappropriate. Another problem is a misdiagnosis of AVB, and improper mode switching occurs when this misdiagnosis is repeated.

The solution according to the invention relates to the regeneration of the AEI in response to the detection of VES, as shown in FIG. 2b, as in the first case; the AEI is regenerated as AEI ^* and the patient's natural speed Corresponding to (and therefore sufficient for blood flow) to generate a stimulus that induces atrial depolarization A ₁ ^* and subsequently to induce ventricular depolarization (and thus without detection of AVB) This is accompanied by a temporary error when applying a stimulus that is kept within acceptable limits on physiological levels. Regeneration of AEI in response to VES has the second result: atrial stimulation A ₁ ^* cannot be applied prematurely after VES, and also results in spontaneous depolarization of the ventricle by interatrioventricular conduction. Becomes reactive again.

The third case shown in FIG. 3 is the stimulation at the end of the extrasystole AEI with the addition of VES associated with the safety stimulus V ₁ (see below) in the absence of spontaneous atrial depolarization. Is a case of intervention. Atrial stimulation A1 at the end of the AEI delay starts counting of time, known as cross-talk monitoring period between atrioventricular (AVCTMP), which is defined generally to 50ms no subsequent atrial stimulation _{A 1} by a period of 94ms.

However, the device is unable to discriminate between true ventricular depolarization (in the case of VES) and in fact detection of ventricular signals derived from atrial electrical stimulation. Because of this uncertainty, prevention adds a safe ventricular stimulation V ₁ , which is typically 100 ms after atrial stimulation A ₁ . This case does not trigger a false AVB diagnosis; this is not a proper AAI mode of operation, which is usually not affected by ventricular activity, but in this case it is different and therefore blood flow status This is because it will have a negative effect.

The fourth case is shown in FIG. 4, as in the previous case, where the end of AEI occurs a few ms before VES and VES occurs during post-stimulation atrial blanking (PSABT). It is. Unlike the previous case where VES is detected but invalid, VES is not detected here (the blanking period temporarily blocks all signal detection after stimulation, thereby preventing saturation of the amplification stage). To do). VES is not detected by the device and atrial stimulation A1 initiated at the end of AEI does not induce ventricular depolarization, because VES results in a composition of conduction transient refractory periods. As a result, the device determines that the A ₁ wave is a blocked atrial wave and regenerates a new interval AEI by indicating a diagnosis of AVB. This diagnosis is actually a false positive because the lack of conducted ventricular depolarization is solely due to the fact that an intervening VES has occurred, not the occurrence of conduction detection constituted by AVB. .

  As in the second case described above, if this state is repeated more than three times out of twelve times, the device switches to the DDD mode in an appropriate manner because this switching is not the result of an authentic AVB. is there. The reproduction of the AEI according to the detection of the VES can solve the problems included in the first and second cases described above. In addition, the present invention provides the third and fourth cases. We propose two techniques that can be applied to solve the problem concerning (and the second case).

  The first technique is shown in the flow chart of FIG. 5, which is a configuration corresponding to the case described above, which is true AVBII by analyzing the AVB-induced environment during the diagnosis of potential AVBII. This is related to withholding AVBII treatment by determining whether it is a misdiagnosis for the latter and in the latter case prohibiting the switch to unnecessary DDD mode. In addition to the abbreviations defined above (StimA, DetR, etc.), two exemplary counters C1 and C2 are presented and implemented by the flowchart. The counter C1 is, for example, a counter initialized with 12 (in this case, the ratio 12/9 between the number of non-extra systolic P waves and the number of non-extra systolic R waves used for the AVBII diagnosis described above) Equivalent to the molecule). The initialization of counter C2 is performed during the detection of suspicion of VES, which occurs at the end of AEI and corresponds to the case of stimulation during the safety window described above, or VES occurs at the same time as the binding interval occurs at the end of AEI. Executed in the case.

  Counter C1 is decremented by 1 for each ventricular event correlated to an atrial event or for each VES whose combined interval clearly shows a different duration from that of AEI. When counter C1 reaches 0, this means that the 12-cycle ventricular event is either a depolarization with a corresponding atrial event or a VES that does not occur at the end of the AEI; The suspicion of AVB in response to the VES occurring at the end of can be cleared (thus resetting the suspicion indicator).

  Counter C2 is initialized to eg 12 (given by a numerical value defined in the same manner as C1), for example, this initialization causes the algorithm to detect a stimulus within the safety window or VES occurs at the end of the AEI It also intervenes when blocked atrial stimulation is analyzed during the last 12 cycles. This counter C2 is decremented by 1 for every ventricular event. This method prohibits AVBII diagnosis when C2> 0. When C2 equals 0, AVBII diagnosis is proven. More precisely, during the detection of VES, the device measures the interval (interval [P, VES]) between the last P wave and the occurrence of VES. If this interval is close to the duration of the AEI, especially if AEI-63 ms <[P, VES] <AEI, the misdiagnosed suspicion indicator is set to '1' (the "misdiagnosed suspicious flag" in the flowchart of FIG. 5). ”Is set). The suspicion indicator is set to '1' during stimulation within the safety window.

  If the blocked atrial stimulation counter C2 is greater than or equal to 1 and the suspicion of misdiagnosis is set to '1', AVBII diagnosis is inhibited for a certain number, eg, 12 cycles. Thus, switching to DDD mode was not initiated when 3 out of 12 atrial stimuli were blocked, whereas in conventional devices this switching was initiated.

  If the device detects any VES with a duration close to AEI, or does not detect a stimulus within the safety window, and no atrial stimulus is blocked, eg, during 12 cycles, an indicator of suspected misdiagnosis is It is reset to 0 and the C2 counter is set to 0. In response to detection of any of the three events described above (ie, an event that sets the misdiagnosed suspicion indicator to '1'), the AVBII prohibition counter C1 is reinitialized to a predetermined value, eg, 12. . This puts the switch to DDD mode on the device and does not prove AVBII diagnosis.

  The second technique relates to prolonging the atrial extrasystole AEI, eg, 63 ms, during detection of VES close to AEI or during stimulation within the safety window. The extension of the extra systolic interval makes it possible to prevent inconsistencies between proper detection of VES and full operation of the AAI mode. This extension lasts for a given delay, for example 12 cycles, unless one of the two events is detected again by the device.

Devices suitable for applying the present invention include, for example, Talent ^™ , Symphony ^™ , Rhapsody ^™ brand pacemakers and Alto ^™ brand defibrillators, commercially available from ELA Medical, Montrouge, France. Can be mentioned. These devices are microprocessor-based systems that include circuitry for receiving, transmitting, and processing detected electrical signals, including memory, data registers, etc. (microcontrollers), and receive software commands remotely It is then possible to store it in memory and execute these instructions to implement the functions of the invention described above. Software instructions for controlling the implanter to perform the functions of the present invention described above are known to those skilled in the art. Detection circuits used to detect cardiac signals in the atrium and ventricle in the left and / or right sinus chambers, and stimulation circuits for applying low energy stimulation pulses to treat heartbeat disorders are known Any suitable design can be used.

  It will be appreciated by persons skilled in the art that the present invention may be practiced other than as described in the above examples, which are for illustrative purposes only.

It is explanatory drawing which showed the 1st case where generation | occurrence | production of VES in a critical period induces an improper operation | movement in the conventional device. FIG. 1b is an illustration showing that improper operation is prevented according to the present invention in the same situation as in FIG. 1a. It is explanatory drawing which showed the 2nd case where VES generate | occur | produces during a critical period similarly to FIG. 1a. FIG. 2 is an explanatory view showing that an inappropriate operation is prevented according to the present invention as in FIG. It is explanatory drawing which showed the 3rd case where VES generate | occur | produces in the critical period in the conventional device. It is explanatory drawing which showed the 4th case where VES generate | occur | produces in the critical period in the conventional device. FIG. 6 is a flow chart illustrating an algorithm applied to diagnose Type II AVB and withhold treatment of AVBII upon detection of a false positive event due to the occurrence of VES during the critical period according to the present invention.

Claims (31)

An active implantable medical device,
Means for detecting spontaneous atrial and ventricular events, including means for detecting the occurrence of premature ventricular contractions (VES) during spontaneous ventricular events;
A means for calculating an atrial supplementary contraction interval (AEI) and a means for initiating a count of the supplementary contraction interval (AEI) calculated in response to detection of an atrial event and the atrial supplementary contraction interval (AEI) Means for applying atrial stimulation at the end of an atrial supplementary contraction interval (AEI) counted when no atrial event is detected;
Means for defining a critical period that precedes or follows the end of a counted atrial supplementary systolic interval (AEI);
Means for determining whether the detected ventricular extrasystole (VES) is in the middle of the critical period in response to detecting a ventricular extrasystole (VES);
Means for recognizing a dangerous condition that the device is unable to properly detect or manage electrocardiographic activity when a ventricular premature contraction (VES) occurs at a particular critical heart wave moment, Means shown as a time approximation of the detected ventricular extrasystole (VES) to the end of the atrial supplementary systolic interval (AEI);
In response to a recognized risk condition, the operating parameter of the device is changed to eliminate the recognized risk condition by regenerating an atrial supplementary contraction interval (AEI) in response to detection of a premature ventricular contraction (VES) Means to
An active implantable medical device comprising:   The apparatus of claim 1, wherein the critical period comprises a temporal window preceding the end of the atrial supplementary systole interval with a given duration.   3. The apparatus of claim 2, wherein the means for changing the at least one operating parameter further comprises means for resetting the count of the atrial supplementary contraction interval in response to the detected ventricular extrasystole.   The apparatus of claim 1, wherein the critical period further comprises a temporal window preceding the end of the atrial supplemental contraction interval with a time of less than 63 ms.   The apparatus of claim 1, wherein the critical period is a post ventricular atrial refractory period (PVARP) preceding the end of an atrial replenishment contraction interval that begins counting in response to detection of an extraventricular contraction.   6. The apparatus of claim 5, wherein the means for changing the at least one operational parameter further comprises means for resetting the count of the atrial supplementary contraction interval in response to the detected ventricular extrasystole.   Means for changing the at least one operating parameter is means for measuring a time course separating the last detected atrial event in response to the occurrence of the premature ventricular contraction and the time of occurrence of the premature ventricular contraction; and (i) If the measured time course is located within a given time interval that is shorter than the calculated atrial replacement contraction interval, and / or (ii) the ventricular stimulation within the safety window following the addition of the atrial stimulus Means for setting an indicator of alleged misdiagnosis when appendage occurs, means for detecting and counting atrial stimulation not followed by a correlated spontaneous ventricular event, and (i) followed by a correlated spontaneous ventricular event. At least one atrial stimulus is detected, and (ii) the mode is switched off for a first preset number of cycles in response to the alleged misdiagnosis indicator being set. 5. Apparatus according comprising a means for inhibiting.   8. The apparatus of claim 7, wherein the given time interval includes a period of less than 63 ms preceding the end of the atrial supplemental contraction interval (AEI).   8. The apparatus of claim 7, wherein the first preset number of cycles is 12 cycles. The means for changing the at least one operating parameter further comprises means for resetting a suspected misdiagnosis indicator in response to detecting an atrial stimulus that is not followed by a correlated ventricular event during a second preset cycle. comprising comprising apparatus of claim 1.   The apparatus of claim 10, wherein the second preset number of cycles is 12 cycles. Means for changing at least one operating parameter further;
Means for measuring a time course separating the last detected atrial event in response to the occurrence of a premature ventricular contraction and the time of occurrence of the premature ventricular contraction;
(I) located within a given time interval where the measured time course is shorter than the calculated atrial supplementary contraction interval, and / or (ii) within the safety window following the addition of atrial stimulation Means for extending the atrial replenishment contraction interval by a preset duration in response to the occurrence of the addition of ventricular stimulation;
The apparatus of claim 5 comprising: The apparatus of claim 12 wherein the 63ms predetermined duration for prolonging the cardiac tufts escape interval.   The means for changing the at least one operating parameter is further calculated an atrial replenishment contraction in response to no detection of an atrial event not followed by a correlated ventricular event during a preset cycle. 13. Apparatus according to claim 12, comprising means for returning to the spacing.   The apparatus according to claim 14, wherein the preset number of cycles is 12 cycles.   The apparatus of claim 1, wherein the critical period further comprises an inter-atrioventricular crosstalk monitoring period following the end of the atrial replenishment contraction interval that begins counting in response to atrial stimulation at the end of the atrial replenishment contraction interval. Means for changing at least one operating parameter further;
Means for measuring a time course separating the last detected atrial event in response to the occurrence of a premature ventricular contraction and the time of occurrence of the premature ventricular contraction;
(I) located within a given time interval where the measured time course is shorter than the calculated atrial supplementary contraction interval, and / or (ii) within the safety window following the addition of atrial stimulation Means for extending the atrial replenishment contraction interval by a preset duration in response to the occurrence of the addition of ventricular stimulation;
The apparatus of claim 16 comprising: The apparatus of claim 17 wherein the 63ms predetermined duration for prolonging the cardiac tufts escape interval.   The means for changing the at least one operating parameter is further calculated an atrial replenishment contraction in response to no detection of an atrial event not followed by a correlated ventricular event during a preset cycle. 18. Apparatus according to claim 17 comprising means for returning to the spacing.   The apparatus of claim 19, wherein the preset number of cycles is twelve.   The apparatus of claim 1, wherein the critical period further comprises a post-stimulation atrial blanking period following the end of the atrial replenishment contraction interval that begins counting in response to atrial stimulation at the end of the atrial replenishment contraction interval. Means for changing at least one operating parameter further;
Means for measuring a time course separating the last detected atrial event in response to the occurrence of a premature ventricular contraction and the time of occurrence of the premature ventricular contraction;
(I) the measured time course is located within a given time interval that is shorter than the calculated duration of the atrial replacement contraction interval and / or (ii) the safety window following the application of the atrial stimulus Means for extending an atrial replenishment contraction interval by a preset duration in response to the addition of ventricular stimulation within the range;
The apparatus of claim 21, comprising: The apparatus of claim 22 wherein the 63ms predetermined duration for prolonging the cardiac tufts escape interval.   The means for changing the at least one operating parameter is further calculated an atrial replenishment contraction in response to no detection of an atrial event not followed by a correlated ventricular event during a preset cycle. 24. The apparatus of claim 22, comprising means for returning to the spacing.   25. The apparatus of claim 24, wherein the preset number of cycles is twelve cycles. The means for changing the at least one operating parameter further comprises determining the last detected atrial event and the time of occurrence of the ventricular extrasystole for a first preset number of cycles in response to the occurrence of the ventricular extrasystole. The apparatus of claim 21, comprising means for measuring the separated time course.   27. The apparatus of claim 26, wherein the given time interval includes a period of less than 63 ms preceding the end of the atrial supplemental contraction interval (AEI). 27. The apparatus of claim 26, wherein the first preset number of cycles is 12 cycles.   The means for changing the at least one operating parameter further comprises means for resetting a suspected misdiagnosis indicator in response to detecting an atrial stimulus that is not followed by a correlated ventricular event during a second preset cycle. 27. The apparatus of claim 26, comprising:   30. The apparatus of claim 29, wherein the second preset number of cycles is 12 cycles. A means of stimulating the ventricles;
Means for detecting the occurrence and repetition of spontaneous or stimulated atrial events not followed by detection of correlated ventricular events and diagnosing interatrioventricular block;
Mode switching means for enabling control of switching from the AAI mode to the DDD mode in response to the diagnosis of the interatrioventricular block;
The apparatus of claim 1, wherein the means for changing at least one operating parameter of the device comprises means for inhibiting mode switching from the AAI mode to the DDD mode.

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