Cardiac pacer which compensates for effects of abrupt changes in heart rate

Abstract

Clinical studies of heart patients have demonstrated that ventricular tachyarrhythmia often is preceded by a foreshortened cardiac cycle length followed by a relatively long compensatory pause, thus producing in an abrupt short-to-long cycle length change. An implantable apparatus for preventing tachyarrhythmia measures the cardiac cycle length and detects the occurrence of a foreshortened cardiac cycle length more than a predefined amount between consecutive cycles. When a normal heart beat does not occur within a predefined period of time after such an abrupt change in cycle length, the resulting compensatory pause is eliminated by a cardiac pacer applying an appropriately timed electrical pulse to produce a contraction of the heart. The apparatus also includes a defibrillator to shock the heart in the event that the preventive pacing is not effective.

Description

BACKGROUND OF THE INVENTIONThe present invention relates to implantable medical devices which deliver energy to cardiac tissue in an attempt to restore a normal sinus rhythm to a patient.Tachycardia refers to any fast, abnormal rhythm of the heart which may be amenable to treatment by electrical discharges. One form of tachycardia is referred to as ventricular tachyarrhythmia (VTA). A common therapy for treating VTA is to implant a cardiac pacer / defibrillator in the patient, Cardiac pacers traditionally have been used to detect a slow heart rate and in response discharge electrical energy into the heart tissue at a faster pace which increases the heart rate. Pacing technology also can respond to the detection of arapid heart rate by producing rapid pacing which terminates the tachycardia and thereby causing the heart rate to return to normal. This present cardiac pacing technology is not specifically designed to reduce the occurrence of ventricular tachyarrhythmia, but rather to ter...

AI Technical Summary

Benefits of technology

A general object of the present invention is to provide an antitachycardia therapy device which detects a premature heartbeat followed by a resulting long pause and responds with corrective action to restore a normal heart rate by preventing the pause. This decreases dispersion and thereby lowers the incidence of VTA.

Another object is to electrically stimulate the heart to shorten the compensatory pause and thus reduce the severity of the short-to-long change in cardiac cycle length.

Problems solved by technology

This present cardiac pacing technology is not specifically designed to reduce the occurrence of ventricular tachyarrhythmia, but rather to terminate the condition after it occurs.

However, rapid pacing techniques can accelerate and worsen the arrhythmias in some instances.

However, occasionally a premature ventricular contraction occurs in the form of a spurious pulse from a muscle cell which disrupts the normal electrical pulse pattern in the heart.

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