Method for delivering cardiac therapy and a cardiac therapy device for implementing the same

Abstract

A method for delivering cardiac therapy, particularly defibrillation therapy, using an implantable cardioverter-defibrillator (ICD) or other cardiac therapy device. The method can be used either alone or in conjunction with any other suitable defibrillation (or other cardiac) therapy regimen. If used in conjunction with a conventional or other suitable defibrillation therapy regimen, the method can be considered to precondition the heart in advance of delivery of the defibrillation shock(s), in order to reduce the defibrillation threshold (DFT), and thus reduce the overall energy required for delivery of effective defibrillation therapy. In either case, in accordance with the method, the voltage gradients (VGs) across a plurality of different regions of the heart are sensed, e.g., using an endocardial sensor array (ESA), and a respective plurality of electrograms (EGMs) are produced in respective EGM channels. The excitable gaps (i.e., the intervals between successive activations) in the different VG regions of the heart are then brought into phase alignment with one another by appropriately timing the delivery of electrical stimulation (e.g., one or more pulses). In this connection, either the timing of the next activation interval can be advanced by delivering an electrical stimulus (pulse) during the excitable gap or in the late repolarization phase of the previous activation, or the activation interval can be extended by delivering an electrical stimulus earlier in the repolarization phase of the previous activation, leading to an extension of the refractory period (i.e., RPE). If three or more EGM channels are used, the excitable gaps in the different VG regions are preferably brought into phase with one another by first bringing the region associated with the near-field EGM channel into phase alignment with the region associated with the EGM channel of the adjacent (next highest) VG region and then successively entraining the thusly entrained regions with the regions associated with the EGM channels corresponding to the successively more distant VG regions, until the regions associated with all EGM channels are brought into phase alignment with one another. Also disclosed is a cardiac therapy device (e.g., an ICD) for implementing this method.