Method and device for responding to the detection of ischemia in cardiac tissue

Abstract

An apparatus and method for monitoring the patient's heart for the presence of ischemia and altering the treatment delivered by an implantable cardiac stimulation device to minimize adverse ischemic effects, e.g., angina pectoris. Embodiments of the present invention are particularly beneficial when used with a rate responsive cardiac stimulation device. Typically, a rate responsive cardiac stimulation device increases its pacing rate (up to a maximum sensor rate) in response to increases in the patient's activity level. The rate of this change is referred to in this patent as the aggressiveness of the rate responsiveness. However, in an ischemic state, the aggressiveness of the rate responsiveness may cause the heart to pace at a rate that exacerbates the ischemic effects. Accordingly, embodiments of the present invention alter the pacing regimen in one or more of the following ways. First, the maximum sensor rate is adaptively decremented in response to a detected ischemic state. Second, the aggressiveness of the rate responsiveness is adaptively decreased in response to a detected ischemic state. Third, the atrio-ventricular delay (AV) delay is adaptively extended in response to a detected ischemic state. Conversely, when an ischemic state is no longer detected, the adapted variable is incrementally returned toward its original value. Accordingly, ischemia can be minimized while still maintaining the rate responsive features of the implantable cardiac stimulation device.