STEPPED CARDIOVERSION SYSTEM FOR AN IMPLANTABLE CARDIOVERTER DEFIBRILLATOR

摘要

A method and apparatus for treating ventricular tachycardia arrhythmias using an ICD system, delivers a series of stepped cardioversion pulses (120, 122, 124, 126) that include at least a first (120) and second (122) cardioversion countershock of low energy values that are less than about 5 joules. The energy values of each cardioversion countershock increase in stepped progressions in each of the subsequent cardioversion countershocks (124, 126). The use of a series of stepped cardioversion pulses (120, 122, 124, 126) minimizes the possibility of 'overstimulating' heart cells in any reentrant loops that are causing the ventricular tachycardia. The leading edge of the series of stepped cardioversion pulses (120, 122, 124, 126) is sufficient to just stimulate any heart cells that are in phase 4, but is not strong enough to stimulate heart cells that are in phase 3. Thus, if a reentrant loop is within the reaches of the leading edge of a pulse, that reentrant loop is converted without the possibility of inducing fibrillation.