Patent ID: 8639325

Claim:
An improved apparatus for treating cardiac arrhythmias, the apparatus including programmably operable circuitry to detect a ventricular tachycardia event in a heart of a patient and to generate electrical shocks to be delivered to a plurality of electrodes, the improvement comprising: in response to a ventricular tachycardia event, establishing a termination window associated with the ventricular tachycardia event that is defined as a time period based on a frequency of the ventricular tachycardia event, causing the apparatus to automatically deliver at least one unpinning shock in the termination window to the patient to generate a relatively low voltage field that is configured to create a depolarized region in the heart for extinguishing the cardiac arrhythmia by destructively interfering with a reentry wave tip of an anatomical reentry associated with the cardiac arrhythmia that is passing through the depolarized region so as to effectively unpin the anatomical reentry, wherein the at least one unpinning shock is applied to provide an energy that is higher than conventional anti-tachy pacing pulses and lower than an expected lower limit of vulnerability of the patient such that the relatively low voltage field created by the at least one unpinning shock is sufficient for unpinning the anatomical reentry from a location in the heart at a core of the anatomical reentry without creating a risk of inducing ventricular fibrillation.