Implantable cardiac stimulation device with detection and therapy for patients with vasovagal syncope

• US 20020004670A1
• Filed: 05/03/2001
• Published: 01/10/2002
• Est. Priority Date: 05/15/2000
• Status: Active Grant

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Original Assignee: Pacesetter Incorporated (Abbott Laboratories)
• Inventors: Florio, Joseph J., Bornzin, Gene A., Hauck, Gregory
• Granted Patent: US 6,647,295 B2
• Time in Patent Office: Days
• US Class Current: 607/9
• CPC Class Codes: A61N 1/36514 controlled by a physiological quantity other than heart potential, e.g. blood pressure controlled by two or more physical parameters A61N1/36585

Abstract

A pacemaker or other implantable cardiac stimulation device is configured with both a rate hysteresis mode and a vasovagal syncope prevention mode. Within the rate hysteresis mode, the pacemaker detects when the intrinsic heart rate of the patient is below an escape rate, then paces the heart at a Base Rate until an intrinsic beat is detected. When programmed in the vasovagal syncope prevention mode, upon detecting the intrinsic rate falling below the Hysteresis Escape Rate, the pacemaker paces the heart at a Vasovagal Syncope Response Rate, which is considerably higher than the Base Rate. The pacemaker is preferably set to the syncope prevention mode for patients prone to recurrent vasovagal syncope. By pacing the heart at the higher Vasovagal Syncope Response Rate, the pacemaker thereby helps prevent a significant drop in blood pressure which might otherwise cause a loss of consciousness in the patient. System and method embodiments are described.

Claims

1. An implantable cardiac stimulation device comprising:

means for defining a programmable Base Rate, a Hysteresis Escape Rate below the Base Rate, and a Vasovagal Syncope Response Rate above the Base Rate;

pulse generating means for generating stimulation pulses at one of the Base Rate, the Hysteresis Escape Rate, and the Vasovagal Syncope Response Rate based on a mode of operation;

pulse generating means for generating stimulation pulses at a predetermined rate;

vasovagal syncope detecting means for detecting a non-rate-based parameter corresponding to vasovagal syncope; and

control means for operating in a Vasovagal Syncope mode whenever the non-rate-based parameter indicates that vasovagal syncope is present, wherein the rate of stimulation pulses are adjusted to the Vasovagal Syncope Response Rate.

2. The stimulation device as of claim 1, wherein the vasovagal syncope detecting means comprises means for detecting when the patient has lost consciousness.

3. The stimulation device as of claim 2, wherein the means for detecting when the patient has lost consciousness comprises a posture sensor capable of detecting when the patient is one of upright or supine.

4. The stimulation device as of claim 2, wherein the means for detecting when the patient has lost consciousness comprises a blood pressure sensor capable of detecting a sudden drop in blood pressure corresponding to hypotension.

5. The stimulation device as of claim 2, wherein the means for detecting when the patient has lost consciousness comprises an impedance pressure sensor capable of detecting that the patient has had a sudden drop in blood filling in the ventricle.

6. The stimulation device as of claim 2, wherein the means for detecting when the patient has lost consciousness comprises a contractility sensor capable of detecting a sudden need for an increase in stimulation rate.

7. The stimulation device as of claim 1, further comprising:

sensing means for sensing ventricular cardiac signals and for determining an intrinsic ventricular heart rate; and

rate detecting means for detecting a sudden drop in the intrinsic heart rate as a secondary indication of vasovagal syncope;

wherein the control means further comprises means for operating in the Vasovagal Syncope mode when the rate detecting means confirms the occurrence of vasovagal syncope.

8. The stimulation device as of claim 7, further comprising:

means for disabling the vasovagal syncope detecting means upon detecting at least one episode of vasovagal syncope and for operating in the Vasovagal Syncope mode for each subsequent detection of a sudden drop in the intrinsic heart rate.

9. The stimulation device as of claim 7, wherein the rate detecting means comprises:

hysteresis means for selectively extending the minimum stimulation pulse escape interval by adding a prescribed hysteresis value upon sensing a ventricular cardiac signal to produce a Hysteresis Escape Rate below the Base Rate; and

means for determining when the intrinsic rate falls below the Hysteresis Escape Rate.

10. The stimulation device as of claim 9, wherein the control means further comprises:

means for controlling the rate of stimulation pulses to the heart in a Hysteresis Rate mode whenever the intrinsic heart rate falls below the Hysteresis Escape Rate and the vasovagal syncope detecting means determines the absence of vasovagal syncope.

11. The stimulation device as of claim 10, wherein the control means further comprises:

inhibiting means, when operating in the Hysteresis Rate mode, for inhibiting the generation of stimulation pulses when the intrinsic ventricular heart rate falls below the Base Rate but above the Hysteresis Escape Rate, and for triggering the generation of stimulation pulses at the Base Rate whenever the intrinsic heart rate falls below the Hysteresis Escape Rate.

12. The stimulation device as of claim 10, further comprising:

means for disabling the Hysteresis Rate mode upon detecting at least one episode of vasovagal syncope.

13. The stimulation device as of claim 2, further comprising:

physiological sensing means for sensing when the patient is at a hemodynamically appropriate rate; and

wherein the control means further comprises means for determining the Vasovagal Syncope Response Rate based on the physiologic sensing means.