Bi-atrial and/or bi-ventricular sequential cardiac pacing systems

• US 5,902,324 A
• Filed: 04/28/1998
• Issued: 05/11/1999
• Est. Priority Date: 04/28/1998
• Status: Expired due to Fees

• Current Assignee: Medtronic Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Incorporated (Medtronic Plc)
• Inventors: Hudrlik, Terence R., Thompson, David L.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): SCHAETZLE, KENNEDY
• Application Number:
  US09/067,751
• Time in Patent Office: 378 Days
• Field of Search: 607/9, 607/123, 600/509
• US Class Current: 607/9
• CPC Class Codes: A61N 1/3627 for treating a mechanical deficiency of the heart, e.g. congestive heart failure or cardiomyopathy
• CPC Class Codes: A61N 1/368 comprising more than one electrode co-operating with different heart regions A61N1/3622, A61N1/3627 take precedence

Abstract

A multi-chamber cardiac pacing systems for providing synchronous pacing to at least the two upper heart chambers or the two lower heart chambers or to three heart chambers or to all four heart chambers employing one or more field density clamp (FDC) sense amplifiers for accurately sensing and timing cardiac depolarizations of the right and left heart chambers is disclosed. The synchronous pacing of one of the right and left heart chambers is provided on demand following expiration of programmable pace CDW and sense CDW that are started by both a paced event and a sensed event first occurring in the other of the right and left heart chambers. The delivery of the pacing pulse is inhibited by a sensed event detected in the other of the right and left heart chambers before the expiration of the corresponding CDW. In a four channel atrial and ventricular pacing system, the right and left atrial chambers are sensed and paced as necessary upon at the end of a V-A escape interval and right and left, pace and sense, AV delays are commenced for sensing ventricular depolarizations in the right and left ventricles. The four channel system is programmable to pace and sense in three selected heart chambers. Each FDC sense amplifier allows the timing of a short CDW from a paced event or a sensed event. Preferably, a pacing output stage is coupled with the FDC sense amplifiers to deliver pacing pulses to each heart chamber.

Claims

1. Apparatus for improving the hemodynamic efficiency of a sick heart suffering from conduction delays in conducting spontaneous or evoked depolarizations originating in a right heart chamber to the left heart chamber comprising:

a right heart lead having first and second pace/sense electrodes located for sensing spontaneous cardiac depolarizations and applying pacing pulses to the right heart chamber to stimulate an evoked depolarization thereof;

a left heart lead having first and second pace/sense electrodes located for sensing spontaneous cardiac depolarizations and applying pacing pulses to the left heart chamber to stimulate an evoked depolarization thereof;

right heart pacing pulse output means responsive to a pace trigger signal for supplying right heart pacing pulses to said right heart lead;

left heart pacing pulse output means responsive to a pace trigger signal for supplying left heart pacing pulses to said left heart lead;

right heart chamber field density clamp sensing means coupled with said right heart chamber lead for sensing spontaneous cardiac depolarizations originating in the right heart chamber and conducted cardiac depolarizations originating in the left heart chamber from a spontaneous cardiac depolarization or delivery of a left heart pacing pulse to the left heart chamber and for providing a right heart chamber sensed event signal in response to either a sensed spontaneous or conducted cardiac depolarization;

left heart chamber field density clamp sensing means coupled with said left heart chamber lead for sensing spontaneous cardiac depolarizations originating in the left heart chamber and conducted cardiac depolarizations originating in the right heart chamber from a spontaneous cardiac depolarization or delivery of a right heart pacing pulse to the right heart chamber a paced event and for providing a left heart chamber sensed event signal in response to either a sensed spontaneous or conducted cardiac depolarization;

escape interval timing means for timing a pacing escape interval from one of the right or left heart chamber sensed event signal or one of the right or left heart chamber pace trigger signal for commencing said pacing escape interval and for generating one of the right or left heart pace trigger signal at the end of said pacing escape interval to thereby provide a basic pacing rate for pacing one of the right or left heart chambers in the absence of a sensed event signal during the pacing escape interval; and

conduction window timing means responsive to one of the right or left heart chamber sensed event signals or one of the right or left heart chamber pace trigger signals for commencing a conduction delay window and for generating said left heart pace trigger signal or said right heart pace trigger signal at the end of said conduction delay window and responsive to a left heart chamber or a right heart chamber sensed event signal during the time out of said conduction delay window for inhibiting the generation of said left heart or right heart pace trigger signal.

2. The apparatus of claim 1, wherein each said field density clamp sense amplifier further comprises:

a virtual load connected to said first pace/sense electrode of said left heart lead means;

an active circuit, coupled to said second pace/sense electrode of said left heart lead means and to said virtual load, for providing electrical energy to said first pace/sense electrode through said virtual load in response to the occurrence of a cardiac depolarization across said first and second pace/sense electrodes to counteract depolarization induced variation in the relative electrode/electrolyte equilibrium of said first and second pace/sense electrodes; and

a monitoring circuit, coupled to said active circuit, for monitoring electrical energy provided through said virtual load, for detecting the occurrence of a cardiac depolarizatione.

3. The pacing system of claim 2, further comprising means for programming said conduction delay window in a range of 0-100 msec.

4. The apparatus of claim 2, wherein said conduction delay window timing means further comprises:

first conduction window timing means responsive to the right heart chamber sensed event signal or the right heart chamber pace trigger signal for commencing a right heart to left heart conduction delay window and for generating said left heart pace trigger signal at the end of said right heart to left heart conduction delay window and responsive to a left heart chamber sensed event signal during the time out of said right heart to left heart signal conduction delay window for inhibiting the generation of said left heart pace trigger signal; and

second conduction window timing means responsive to the left heart chamber sensed event signal or the left heart chamber pace trigger signal for commencing a left heart to right heart conduction delay window and for generating said right heart pace trigger signal at the end of said left heart to right heart conduction delay window and responsive to a right heart chamber sensed event signal during the time out of said left heart to right heart signal conduction delay window for inhibiting the generation of said right heart pace trigger signal.

5. The pacing system of claim 4, further comprising:

means for programming said left heart chamber conduction delay window in a range of 0-100 msec; and

means for programming said right heart chamber conduction delay window in a range of 0-100 msec.

6. The apparatus of claim 1, wherein said conduction delay window timing means further comprises:

first conduction window timing means responsive to the right heart chamber sensed event signal or the right heart chamber pace trigger signal for commencing a right heart to left heart conduction delay window and for generating said left heart pace trigger signal at the end of said right heart to left heart conduction delay window and responsive to a left heart chamber sensed event signal during the time out of said right heart to left heart signal conduction delay window for inhibiting the generation of said left heart pace trigger signal; and

second conduction window timing means responsive to the left heart chamber sensed event signal or the left heart chamber pace trigger signal for commencing a left heart to right heart conduction delay window and for generating said right heart pace trigger signal at the end of said left heart to right heart conduction delay window and responsive to a right heart chamber sensed event signal during the time out of said left heart to right heart signal conduction delay window for inhibiting the generation of said right heart pace trigger signal.

7. The pacing system of claim 6, further comprising:

means for programming said left heart chamber conduction delay window in a range of 0-100 msec; and

means for programming said right heart chamber conduction delay window in a range of 0-100 msec.

8. The pacing system of claim 1, wherein the right heart chamber is the right atrium and the left heart chamber is the left atrium.

9. The pacing system of claim 1, wherein the right heart chamber is the right ventricle and the left heart chamber is the left ventricle.

10. A pacing method for improving the hemodynamic efficiency of a sick heart suffering from conduction delays in conducting spontaneous or evoked depolarizations originating in a right heart chamber to the corresponding left heart chamber comprising the steps of:

locating first and second right heart chamber pace/sense electrodes in relation with the right heart chamber;

locating first and second left heart chamber pace/sense electrodes in relation with the left heart chamber;

coupling a right heart chamber field density clamp sense amplifier with said first and second right heart chamber pace/sense electrodes;

coupling a left heart chamber field density clamp sense amplifier with said first and second left heart chamber pace/sense electrodes;

sensing spontaneous and evoked cardiac depolarizations in the right heart chamber across said right heart chamber pace/sense electrodes with said right heart chamber field density clamp sense amplifier and providing a right heart chamber sensed event signal;

sensing spontaneous and evoked cardiac depolarizations in the left heart chamber across said left heart chamber pace/sense electrodes with said left heart chamber field density clamp sense amplifier and providing a left heart chamber sensed event signal;

timing an escape interval establishing a pacing rate and providing an escape interval pace trigger signal at the time out of the escape interval;

restarting the timing of the escape interval in response to the right heart chamber sensed event signals;

in response to the escape interval pace trigger signal, triggering the right heart pacing pulse output means coupled with said right heart chamber pace/sense electrodes to generate and deliver a right heart pacing pulse to said right heart chamber pace/sense electrodes to evoke a right heart chamber depolarization;

timing a left heart chamber conduction delay window from a right heart chamber sensed event signal or from generation of a right heart pacing pulse and providing a left heart chamber pace trigger signal at the expiration of the left heart chamber conduction delay window

terminating the timing out of the left heart chamber conduction delay window in response to a left heart chamber sensed event signal; and

applying said left heart chamber pace trigger signal to said left heart pacing pulse output means to trigger the generation and delivery of a left heart pacing pulse to said left heart chamber lead means;

whereby an excessive conduction delay between a spontaneous or evoked depolarization in the right heart chamber and the conducted depolarization wave in the left heart chamber is corrected by generation and delivery of a pacing pulse at the timing out of the conduction delay window.

11. The pacing method of claim 10, wherein the right heart chamber is the right atrium and the left heart chamber is the left atrium.

12. The pacing method of claim 11, further comprising the step of:

programming said left heart chamber conduction delay window in a range of 0-100 msec.

13. The pacing method of claim 10, wherein the right heart chamber is the right ventricle and the left heart chamber is the left ventricle.

14. The pacing method of claim 13, further comprising the step of:

programming said left heart chamber conduction delay window in a range of 0-100 msec.

15. The pacing method of claim 10, further comprising the steps of:

preventing the sensing of spontaneous and evoked cardiac depolarizations in the right heart chamber and the provision of a right heart chamber sensed event signal in response thereto for the duration of a right heart chamber blanking period in response to the generation of a right heart pacing pulse and a left heart pacing pulse; and

preventing the sensing of spontaneous and evoked cardiac depolarizations in the left heart chamber and the provision of a left heart chamber sensed event signal in response thereto for the duration of a left heart chamber blanking period in response to the generation of a right heart pacing pulse and a left heart pacing pulse.

16. The pacing method of claim 15, wherein the right heart chamber is the right atrium and the left heart chamber is the left atrium.

17. The pacing method of claim 16, further comprising the step of:

programming said left heart chamber conduction delay window in a range of 0-100 msec.

18. The pacing method of claim 15, wherein the right heart chamber is the right ventricle and the left heart chamber is the left ventricle.

19. The pacing method of claim 18, further comprising the step of:

programming said left heart chamber conduction delay window in a range of 0-100 msec.

20. The method of claim 10, wherein each said field density clamp sense amplifier further comprises:

a virtual load connected to said first pace/sense electrode of said left heart lead means;

an active circuit, coupled to said second pace/sense electrode of said left heart lead means and to said virtual load, for providing electrical energy to said first pace/sense electrode through said virtual load in response to the occurrence of a cardiac depolarization across said first and second pace/sense electrodes to counteract depolarization induced variation in the relative electrode/electrolyte equilibrium of said first and second pace/sense electrodes; and

a monitoring circuit, coupled to said active circuit, for monitoring electrical energy provided through said virtual load, for detecting the occurrence of a cardiac depolarization.