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

• US 7,020,524 B1
• Filed: 10/24/2002
• Issued: 03/28/2006
• 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:
  US10/280,756
• Time in Patent Office: 1,251 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 comprising:

detection circuitry adapted to be coupled to at least one electrode in an atrium and to at least one electrode in a ventricle, the detection circuitry being operative to receive cardiac signals from the respective electrodes to detect atrial events and intrinsic ventricular events;

a pulse generator adapted to be coupled to the at least one electrode in the ventricle and configured to generate stimulation pulses to stimulate the ventricle; and

a controller connected to the detection circuitry and operative to determine, at various times, heart rates based on at least one of the atrial events and intrinsic ventricular events, and to calculate delay values between atrial events and intrinsic ventricular events for a plurality of different heart rates, wherein the controller is operative to control the pulse generator to perform a ventricular capture threshold search using an atrio-ventricular delay that is based on a current heart rate and the calculated delay value for the current heart rate.

2. The device of claim 1 wherein the controller creates a table to store the heart rates and corresponding calculated delay values.

3. The device of claim 2 wherein:

the corresponding delay values 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.

4. The device of claim 1 wherein the controller determines the heart rate based upon at least two sequential intrinsic events in a chamber of the patient'"'"'s heart.

5. The device of claim 4 wherein the heart rate is based upon at least two sequential P-waves.

6. The device of claim 1, wherein the controller is operative to calculate the atrio-ventricular delay by shortening the corresponding calculated delay value by a selected amount.

7. A method for performing a capture threshold test for a ventricle of a patient'"'"'s heart, the method comprising:

determining delay values between atrial events and intrinsic ventricular events for a plurality of different heart rates; and

performing the capture threshold test using an atrio-ventricular delay that is based on a current heart rate and the delay value corresponding to the current heart rate.

8. The method of claim 7 wherein measuring the delay value is done using an automatic intrinsic conduction search.

9. The method of claim 7 wherein the heart rate corresponds to time periods between at least two sequential intrinsic events in a chamber of the patient'"'"'s heart.

10. The method of claim 9 wherein the heart rate is based upon at least two sequential P-waves.

11. The method of claim 10 wherein the atrial event comprises one of a P-wave and an atrial stimulation pulse.

12. The method of claim 7 further comprising:

storing the delay values by creating a table in which to store the measured delays, and separating the delays into two groups comprising;

1) delays between P-waves and R-waves; and

2) delays between atrial stimulation pulses and R-waves.

13. The method of claim 7 wherein the delay value is determined as a function of an average of measured delays associated with a current heart rate.

14. The method of claim 7 wherein the atrio-ventricular delay is calculated by shortening the corresponding delay value by a selected amount.

15. An implantable cardiac stimulation device comprising:

means for determining delay values between atrial events and intrinsic ventricular events for a plurality of heart rates; and

means for performing a capture threshold test using an atrio-ventricular delay that is based on a current heart rate and the corresponding delay value.

16. The device of claim 15, further comprising means for determining time periods between at least two sequential intrinsic events in a chamber of the patient'"'"'s heart.

17. The device of claim 15 wherein the atrial events comprise one or more of a P-wave and an atrial stimulation pulse.

18. The device of claim 15 wherein the means for determining delay values comprises means for determining delay values as a function of an average of measured delays associated with a current heart rate.

19. The device of claim 15 wherein the means for performing comprises means for calculating the atrio-ventricular delay by shortening the corresponding delay value by a selected amount.