This 57-year-old man presenting with ischemic cardiomyopathy and episodes of sustained VT complicated by syncope received a Fortify single chamber ICD. He was seen in consultation after he experienced electrical shocks.
Episode of VF with ATP delivered during the capacitors charge and cancelled electrical shock.
Tracing
Narrative
New VF episode with ATP during the charge, followed by 36-J shock.
Tracing
Narrative
New VF episode with delivery of ATP followed by 36-J shock.
Tracing
A priority objective of ICD programming is to minimize the risk of electrical shock delivery, while preserving the patient’s safety. A large proportion of fast tachycardias diagnosed in the VF zone are organized, monomorphic, and amenable to ATP therapy. Pacing during the charge of the capacitors can be, therefore, offered to lower the likelihood of electrical shocks. The diagnosis of VF triggers the charge of the capacitors and the ATP sequence simultaneously. The shock is not delivered if ATP is successful. In this patient, a clear advantage consisted in the termination of the tachycardia without shock delivery, a key ingredient of his quality of life. On the other hand, the charge of the capacitors consumes energy, which might be problematic if repetitive. However, the shock was diverted, preventing a full charge, and sparing some battery life. Had ATP been unsuccessful, the charge would have continued uninterrupted, and the shock would not have been delayed by ATP. On the last tracing, the salvo of ATP was successful, though the tachycardia recurred before the diagnosis of restoration of sinus rhythm and the shock was delivered at the end of the charge.
