Pacemaker with improved automatic output regulation

• US 4,969,467 A
• Filed: 08/07/1989
• Issued: 11/13/1990
• Est. Priority Date: 03/25/1988
• Status: Expired due to Term

• Current Assignee: Pacesetter Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Telectronics Incorporated
• Inventors: Vollmann, William, Callaghan, Francis J.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): Manuel, George
• Application Number:
  US07/390,525
• Time in Patent Office: 463 Days
• Field of Search: 128/419 PG, 128/419 PT, 128/419 P
• US Class Current: 607/28
• CPC Class Codes: A61N 1/36507 controlled by gradient or slope of the heart potential
• CPC Class Codes: A61N 1/3706 Pacemaker parameters stimulation threshold A61N1/371
• CPC Class Codes: A61N 1/3712 Auto-capture, i.e. automatic adjustment of the stimulation threshold

Abstract

A pacemaker which is provided with an improved automatic regulation circuit which is capable of distinguishing between a fashion beat and loss of capture. The failure to sense an evoked potential following a stimulus may be due to either. The cause is determined by generating a high-energy back-up pulse shortly after the stimulus. Failure to capture by the back-up pulse is an indication that there was just a fusion beat; the sensing of an evoked potential is an indication that the stimulus failed to capture.

Claims

1. A pacemaker comprising means for generating pacing pulses;

means for adjusting the magnitude of said pacing pulses;

means for sensing an evoked potential following the generation of a pacing pulse in order to determine if an adjustment is required in the magnitude of said pacing pulses; and

means responsive to the failure to sense an evoked potential following the generation of a pacing pulse for increasing the pacing rate so that if said failure was due to a fusion beat, then the next pacing pulse is more likely to result in a heart capture.

2. A pacemaker in accordance with claim 1 wherein said rate increasing means increases the pacing rate in both of two successive heart cycles responsive to two successive failures to sense evoked potentials.

3. A pacemaker in accordance with claim 1 further including means for controlling the generation of a back-up pacing pulse responsive to the failure to sense an evoked potential.

4. A pacemaker in accordance with claim 3 further including means responsive to the failure to sense an evoked potential following generation of a back-up pacing pulse for determining that the preceding pacing pulse resulted in a fusion beat.

5. A pacemaker in accordance with claim 4 wherein said determining means is further operative, responsive to the sensing of an evoked potential following generation of a back-up pulse, for determining that the preceding pacing pulse resulted in a heart capture failure.

6. A pacemaker in accordance with claim 4 further including means responsive to the sensing of an evoked potential following generation of a back-up pulse for determining that the preceding pacing pulse resulted in a heart capture failure.

7. A method of operating a pacemaker comprising the steps of generating pacing pulses;

adjusting the magnitude of said pacing pulses;

sensing an evoked potential following the generation of a pacing pulse in order to determine if an adjustment is required in the magnitude of said pacing pulses; and

responsive to the failure to sense an evoked potential following the generation of a pacing pulse, increasing the pacing rate so that if said failure was due to a fusion beat, then the next pacing pulse is more likely to result in a heart capture.

8. A method of operating a pacemaker in accordance with claim 7 wherein said rate is increased in both of two successive heart cycles responsive to two successive failures to sense evoked potentials.

9. A method of operating a pacemaker in accordance with claim 7 further including the step of controlling the generation of a back-up pacing pulse responsive to the failure to sense an evoked potential.

10. A method of operating a pacemaker in accordance with claim 9 wherein, responsive to the failure to sense an evoked potential following generation of a back-up pacing pulse, it is determined that the preceding pacing pulse resulted in a fusion beat.

11. A method of operating a pacemaker in accordance with claim 10 wherein, responsive to the sensing of an evoked potential following generation of a back-up pulse, it is determined that the preceding pacing pulse resulted in a heart capture failure.