Non-captured intrinsic discrimination in cardiac pacing response classification

Abstract

Cardiac devices and methods discriminate non-captured intrinsic beats during evoked response detection and classification by comparing the features of a post-pace cardiac signal with expected features associated with a non-captured response with intrinsic activation. Detection of a non-captured response with intrinsic activation may be based on the peak amplitude and timing of the cardiac signal. The methods may be used to discriminate between a fusion or capture beat and a non-captured intrinsic beat. Discriminating between possible cardiac responses to the pacing pulse may be useful, for example, during automatic capture verification and / or a capture threshold test.

Description

FIELD OF THE INVENTION [0001] The present invention relates generally to implantable medical devices and, more particularly, to cardiac devices and methods that discriminate non-captured intrinsic beats during evoked response detection. BACKGROUND OF THE INVENTION [0002] When functioning normally, the heart produces rhythmic contractions and is capable of pumping blood throughout the body. However, due to disease or injury, the heart rhythm may become irregular resulting in diminished pumping efficiency. Arrhythmia is a general term used to describe heart rhythm irregularities arising from a variety of physical conditions and disease processes. Cardiac rhythm management systems, such as implantable pacemakers and cardiac defibrillators, have been used as an effective treatment for patients with serious arrhythmias. These systems typically include circuitry to sense electrical signals from the heart and a pulse generator for delivering electrical stimulation pulses to the heart. Lead...

AI Technical Summary

Benefits of technology

[0011] The present invention involves various cardiac devices and methods that discriminate non-captured intrinsic beats during evoked response detection and classification. An embodiment of a method of classifying a cardiac response to a pacing pulse in accordance with the present invention involves delivering pacing pulse to a heart and sensing a cardiac signal following delivery of the pacing pulse. The cardiac response to the pacing pulse is classified as a non-captured intrinsic beat based on one or more characteristics of the cardiac signal. Classifying the cardiac response may involve detecting one or both of a peak time and peak amplitude of the cardiac signal, and may be based on one or both of the peak time and peak amplitude.

Problems solved by technology

However, due to disease or injury, the heart rhythm may become irregular resulting in diminished pumping efficiency.

If the pace pulse energy is too low, the pace pulses may not reliably produce a contractile response in the heart and may result in ineffective pacing.

If the pace pulse energy is too high, the patient may experience discomfort and the battery life of the device will be shorter.

In pseudofusion, the pacing stimulus may be ineffective because the tissue around the electrode has already spontaneously depolarized and is in its refractory period.

Noise presents a problem in evoked response detection processes when the pacemaker mistakenly identifies noise as capture, fusion / pseudofusion, or intrinsic activity.

Noise mistakenly identified as capture or fusion / pseudofusion may cause a pacemaker to erroneously withhold backup pacing under loss of capture conditions.

Noise mistakenly identified as non-captured intrinsic activity may lead to a premature loss of capture determination during threshold testing.

These non-captured intrinsic beats represent a loss of capture.

The misclassification of non-captured intrinsic beat to capture or fusion beats may result in low threshold measurement during threshold testing.

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