Gene Expression in ICD Patients With Electrical Storm

This is a study of patients with ICD implants who present with multiple(>2), low-level(1-2) or inappropriate therapies to their defibrillator. The purpose of this pilot study is to identify factors which are associated with periods of high ventricular arrhythmia burden by looking at gene expression from peripheral blood, in addition to levels of known markers of CHF, including catecholamine levels, B-type natriuretic peptide, and troponin. This study hypothesizes that extrinsic or systemic factors play a role in triggering these events, and if true should yield candidate proteins which would spawn functional studies to prove a role in causation. Additionally, identification of a marker of increased recurrence of events may aid in guiding therapy (starting an anti-arrhythmic versus awaiting the next event).