Cardiac stimulating apparatus and method for heart failure therapy

• US 5,584,868 A
• Filed: 07/27/1994
• Issued: 12/17/1996
• Est. Priority Date: 11/03/1992
• Status: Expired due to Term

• Current Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Original Assignee: Cardiac Pacemakers Incorporated (Boston Scientific Corporation)
• Inventors: Spinelli, Julio C., Tockman, Bruce A., Salo, Rodney W.
• Primary Examiner(s): Kamm, William E.
• Assistant Examiner(s): Getzow, Scott M.
• Application Number:
  US08/281,476
• Time in Patent Office: 874 Days
• Field of Search: 607/24, 607/17, 607/14, 607/18
• US Class Current: 607/17
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• 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 1/3682 with a variable atrioventricular delay
• CPC Class Codes: A61N 1/39622 Pacing therapy

Abstract

A cardiac rhythm management device and method includes a dual-chamber pacemaker especially designed for treating congestive heart failure and a defibrillator as a back-up measure. The device incorporates a programmed microcontroller which is operative to adjust the AV delay of the pacemaker to a minimum or maximum length consistent with optimal cardiac function. The cardiac stimulator includes apparatus for sensing cardiac function from cycle-to-cycle and determining whether incremental changes made to the AV delay interval enhances or worsens the measured cardiac function. On each iterative cycle, the AV delay interval is changed, either incremented or decremented, until a cross-over point is reached in which it is noted that the cardiac function ceases to improve and this is followed with a further incremental adjustment in an opposite direction to compensate for any overshoot. By providing a cardiac defibrillator in combination with the pacing device with closed-loop control of the AV interval, incidences of sudden death due to lethal arrhythmias is reduced.

Claims

1. A method of operating an implantable cardiac stimulator implanted in a patient suffering from congestive heart failure, said cardiac stimulator being of the type having means for sensing atrial activity, means for sensing ventricular activity;

means for sensing cardiac function of the patient'"'"'s heart, means for stimulating only at least one ventricular chamber at a programmed rate, and microprogrammable controller means coupled to said means for sensing said atrial activity, said means for sensing ventricular activity, and said means for sensing cardiac function, said microprogrammable controller means controlling said means for stimulating only at least one ventricular chamber so as to issue ventricular stimulating pulses at said programmed rate at computed AV delay intervals following the sensing of an atrial event, comprising the steps of;

(a) adjusting said AV interval in incremental steps to a predetermined AV delay limiting value;

(b) for each of said incremental steps, monitoring a predetermined cardiac function of the heart to determine whether a given incremental change in said AV interval results in improved cardiac function; and

(c) setting said AV interval at the greatest length less than or equal to the predetermined limiting value that yields maximal cardiac function.

2. A totally implantable cardiac stimulating apparatus for treating congestive heart failure comprising, in combination:

(a) means for sensing atrial activity;

(b) means for sensing ventricular activity;

(c) means for sensing cardiac output;

(d) ventricular stimulating means;

(e) a programmable microcontroller coupled to said atrial sensing means, said ventricular sensing means and said means for sensing cardiac output for producing control signals for controlling said ventricular stimulating means with said ventricular stimulating means generating ventricular stimulating pulses following AV delay intervals calculated by said programmable microcontroller from the sensing of atrial activity, said AV delay intervals being the shortest length yielding maximal cardiac function as derived from said cardiac output sensing means.

3. An implantable cardiac rhythm management device for treating CHF comprising, in combination:

(a) means for sensing intrinsic atrial activity;

(b) means for sensing intrinsic ventricular activity;

(c) means for sensing cardiac function;

(d) means responsive to said means for sensing intrinsic atrial activity and said means for sensing intrinsic ventricular activity for producing low energy cardiac stimulating pulses following an atrioventricular delay interval;

(e) means for applying said cardiac stimulating pulses solely to ventricular tissue; and

(f) means responsive to said means for sensing cardiac function for modifying only the length of said atrioventricular delay interval in incremental steps so long as the modifications result in improvements in cardiac function.

4. The implantable cardiac rhythm management device as in claim 3 and further including:

(a) arrhythmia detecting means responsive to said means for sensing intrinsic ventricular activity;

(b) cardioverting means for producing high energy cardiac stimulating pulses; and

(c) means for applying said high energy cardiac stimulating pulse to ventricular tissue when said arrhythmia detecting means senses potentially lethal arrhythmia.

5. The implantable cardiac rhythm management device as in claim 3 wherein said means for applying said cardiac stimulating pulses to ventricular tissue comprises:

(a) an elongated, flexible, pacing lead means coupled to said means for producing said low energy cardiac stimulating pulses and having stimulating electrodes thereon for contacting both ventricles of the heart.