Implantable cardiac stimulation device having optimized AV/PV delays for improved atrial kick during automatic capture and threshold determinations

• US 6,498,950 B1
• Filed: 10/17/2000
• Issued: 12/24/2002
• Est. Priority Date: 10/17/2000
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Inventors: Bradley, Kerry A
• Primary Examiner(s): Jastrzab, Jeffrey R.
• Application Number:
  US09/690,641
• Time in Patent Office: 798 Days
• Field of Search: 607/9, 607/11, 607/27, 607/28
• US Class Current: 607/27
• CPC Class Codes: A61N 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

An improved device and method for performing automatic capture/threshold determination that is particularly useful in an implantable cardiac stimulation device. While conventional devices use a fixed shortening of the AV/PV delays during automatic capture/threshold determinations, any shortening can unnecessarily cause discomfort to patients with heart blocks and unnecessarily diminish the atrial kick for other patients. Accordingly, embodiments of the present invention periodically measure the AR/PR conduction times and tabulate and/or otherwise process this data. Preferably, these measured conduction times are also correlated with the current heart rate. Finally, when an automatic capture/threshold determination occurs, this measured conduction data, which corresponds to this patient, is used to adjust the AV/PV delays while minimizing patient discomfort and adverse hemodynamic effects. Alternatively, the AV/PV delays may be manually programmable by a medical practitioner.

Claims

1. An implantable cardiac stimulation device configured for sensing an atrial event through a first electrode to receive electrical signals from atrial tissue of a patient'"'"'s heart and for stimulating the ventricle of a patient'"'"'s heart through a second electrode implanted in electrical contact with ventricular tissue of the patient'"'"'s heart, the stimulation device comprising:

a first detection circuit coupled to the first electrode and configured to receive cardiac signals for determining the presence or absence of an atrial event;

a ventricular pulse generator electrically coupled to the second electrode and configured to generate ventricular stimulation pulses at a controlled energy level to thereby stimulate the ventricle of the patient'"'"'s heart;

a second detection circuit electrically coupled to the second electrode and configured to receive cardiac signals for determining the presence or absence of a ventricular event wherein the ventricular event alternatively includes an evoked response to each of the stimulation pulses or an intrinsic ventricular depolarization;

a controller coupled to the pulse generator for increasing the ventricular stimulation pulse energy level in response to the absence of at least one evoked response to a ventricular stimulation pulse; and

whereby

the controller periodically causes the ventricular pulse generator to generate ventricular stimulation pulses a threshold detection delay period after an atrial event and whereby the threshold detection delay period is determined based upon a measured time between an atrial event and an intrinsic ventricular depolarization.

2. The device of claim 1 wherein the atrial event is alternatively the presence of a P-wave or the generation of an atrial stimulation pulse.

3. The device of claim 1 additionally comprising:

a table for storing a plurality of measured time periods between atrial events and intrinsic ventricular depolarizations; and

wherein

the controller determines the threshold detection delay period based upon the plurality of measured time periods.

4. The device of claim 1 wherein the controller causes the ventricular pulse generator to deliver a ventricular stimulation pulse at the end of a defined period of time following an atrial event if the second detection circuit does not detect an intrinsic ventricular depolarization.

5. The device of claim 4 wherein the controller periodically causes the defined period of time to be extended to search for an intrinsic ventricular depolarization.

6. The device of claim 5 wherein the controller stores a measured time period between the atrial event and the intrinsic ventricular depolarization when the intrinsic ventricular depolarization occurs during the extended time period.

7. The device of claim 6 wherein data corresponding to the measured time periods are stored in a table.

8. The device of claim 7 wherein:

the measured time periods are in two classes corresponding to;

1) time periods between P-waves and R-waves; and

2) time periods between atrial stimulation pulses and R-waves; and

wherein

the table separately stores data corresponding to each of the two time period classes.

9. The device of claim 8 wherein the device determines a cardiac cycle rate based upon at least two sequential intrinsic events in a chamber of the patient'"'"'s heart.

10. The device of claim 9 wherein the cardiac cycle rate is based upon at least two sequential P-waves.

11. The device of claim 9 wherein the table is comprised of a plurality of bins corresponding to cardiac cycle rates and the measured time periods are stored in cardiac cycle rate bins corresponding to the cardiac cycle rate when the measurement was made.

12. A method for determining the threshold value for a stimulation pulse for stimulating the ventricle of a patient'"'"'s heart during a cardiac cycle through at least one electrode implanted in electrical contact with ventricular cardiac tissue, the method comprising the steps of:

periodically measuring the patient'"'"'s cardiac cycle rate;

periodically measuring the delay between an atrial event and an intrinsic ventricular event;

storing the measured delay in association with the measured cardiac cycle rate; and

periodically determining the threshold value for stimulating the patient'"'"'s heart whereby the periodically determining step comprises the steps of;

setting a delay interval for delivering a stimulation pulse to the ventricle of the patient'"'"'s heart following an atrial event according to a current cardiac cycle rate and the associated stored measured delay, wherein the delay interval is reduced from an operating delay interval;

determining an atrial event;

periodically stimulating the ventricle of the patient'"'"'s heart with a stimulation pulse following the atrial event according to the set delay interval, the stimulation pulse having a controlled energy level;

detecting the presence or absence of an evoked response generated by the patient'"'"'s heart in response to the stimulation pulse during a detection window; and

increasing the controlled energy level the stimulation pulse in response to the absence of at least one evoked response.

13. The method of claim 12 wherein the periodically measuring the delay step is done using an automatic intrinsic conduction search.

14. The method of claim 12 wherein the periodically measuring the delay step is done by physician.

15. The method of claim 12 wherein the cardiac cycle rate corresponds to time periods between at least two sequential intrinsic events in a chamber of the patient'"'"'s heart.

16. The method of claim 15 wherein the cardiac cycle rate is based upon at least two sequential P-waves.

17. The method of claim 12 wherein the atrial event is alternatively the presence of a P-wave or the generation of an atrial stimulation pulse.

18. The method of claim 12 wherein:

the storing step stores the measured delays in a table; and

wherein

the table distinguishes delays between;

1) P-waves and R-waves; and

2) atrial stimulation pulses and R-waves.

19. The method of claim 12 wherein the periodically measuring step additionally includes waiting an extended delay period for an intrinsic ventricular event following an atrial event.

20. The method of claim 19 wherein the delay interval is not reduced from the operating delay interval if an intrinsic ventricular event does not follow an atrial event.

21. The method of claim 19 wherein the delay interval is reduced by a detection window time if an intrinsic ventricular event does not follow an atrial event.

22. The method of claim 12 wherein the delay interval is determined as a function of an average of the measured delays associated with the current cardiac cycle rate.

23. The method of claim 12 wherein the delay interval is determined as a function of the mean and standard deviation of the measured delays associated with the current cardiac cycle rate.

24. The method of claim 12 wherein the delay interval is determined according to the type of atrial event and the cardiac cycle rate.

25. An implantable cardiac stimulation device configured for sensing an atrial event through a first electrode implanted to receive an electrical signal from atrial tissue of a patient'"'"'s heart and for stimulating the ventricle of a patient'"'"'s heart through a second electrode implanted in electrical contact with ventricular tissue of the patient'"'"'s heart, the stimulation device comprising:

a first detection circuit coupled to the first electrode and configured to receive cardiac signals for determining the presence or absence of an atrial event;

a ventricular pulse generator electrically coupled to the second electrode and configured to generate ventricular stimulation pulses at a controlled energy level to thereby stimulate the ventricle of the patient'"'"'s heart;

a second detection circuit electrically coupled to the second electrode and configured to receive cardiac signals for determining the presence or absence of a ventricular event wherein the ventricular event alternatively includes an evoked response to each of the stimulation pulses or an intrinsic ventricular depolarization;

a controller coupled to the pulse generator for increasing the ventricular stimulation controlled energy level in response to the absence of at least one evoked response to a ventricular stimulation pulse; and

wherein

the controller periodically causes the ventricular pulse generator to generate ventricular stimulation pulses a threshold detection delay period after an atrial event and whereby the threshold detection delay, period is determined according to data received from an external programmer.

26. The device of claim 25 wherein the controller causes the ventricular pulse generator to deliver a ventricular stimulation pulse at the end of a defined period of time following an atrial event if the second detection circuit does not detect an intrinsic ventricular depolarization.

27. The device of claim 25 wherein data from the external programmer can specify that the threshold detection delay period is essentially the same as the defined period of time.

28. The method of claim 25 wherein the threshold detection period is reduced by a detection window time if an intrinsic ventricular event does not follow an atrial event.

29. An implantable cardiac stimulation device configured for sensing an atrial event through a first electrode to receive electrical signals from atrial tissue of a patient'"'"'s heart and for stimulating the ventricle of a patient'"'"'s heart through a second electrode implanted in electrical contact with ventricular tissue of the patient'"'"'s heart, the stimulation device comprising:

first detection means for determining the presence or absence of an atrial event via cardiac signals received from the first electrode;

pulse generating means for generating ventricular stimulation pulses at a controlled energy level to thereby stimulate the ventricle of the patient'"'"'s heart via the second electrode;

second detection means for determining the presence or absence of a ventricular event via cardiac signals received from the second electrode, wherein the ventricular event alternatively includes an evoked response to each of the stimulation pulses or an intrinsic ventricular depolarization;

control means coupled to the pulse generating means for increasing the ventricular stimulation pulse energy level in response to the absence of at least one evoked response to a ventricular stimulation pulse; and

whereby

the control means periodically causes the pulse generating means to generate ventricular stimulation pulses a threshold detection delay period after an atrial event and whereby the threshold detection delay period is determined based upon a measured time between an atrial event and an intrinsic ventricular depolarization.