Asymptomatic Sustained Ventricular Fibrillation in a Patient With Left Ventricular Assist Device

Optimal medical treatment, cardiac resynchronization, and the use of an implantable cardioverter defibrillator are established therapies of severe congestive heart failure. In refractory cases, left ventricular assist devices are more and more used not only as bridging to cardiac transplantation but also as destination therapy. Ventricular arrhythmias may represent a life-threatening condition and often result in clinical deterioration in patients with congestive heart failure. We report a case of asymptomatic sustained ventricular fibrillation with preserved hemodynamics caused by a nonpulsatile left ventricular assist device. Consecutive adequate but unsuccessful discharges of the implantable cardioverter defibrillator were the only sign of the usually fatal arrhythmia, prompting the patient to consult emergency services. Electrolyte supplementation and initiation of therapy with amiodarone followed by external defibrillation resulted in successful restoration of a stable cardiac rhythm after 3.5 hours.

Introduction

Congestive heart failure affects about 5 million people in the United States,¹ and is a major contributing factor to death and hospitalization despite improved medical treatment, cardiac resynchronization therapy, and the use of implantable cardioverter defibrillators. More than 100,000 patients are estimated to have severe, refractory congestive heart failure, with a dismal prognosis.² Because the option of cardiac transplantation is limited by organ availability and extended wait times, there is an increasing need for mechanical cardiac support not only for bridging but also as a permanent alternative to heart transplantation, the latter often referred to as destination therapy.2, 3, 4

Mechanical pumps have been designed to ensure adequate central and peripheral blood supply and can be positioned as a biventricular, right ventricular, or left ventricular assist device.⁵ Left ventricular assist devices are most commonly used, having an inflow cannula that channels blood from the left ventricle or atrium to the pump and an outflow cannula directing blood from the pump to the ascending aorta. The first-generation assist devices are volume-displacement pumps. Consisting of a chamber filled passively or by suction and compressed by externally applied pressure, they provide a pulsatile flow, thereby mimicking the cyclic systole and diastole of the heart. The second generation has been developed with axial-flow, rotary-pump technology, providing a continuous blood flow. Major advantages are a smaller pump size, greater long-term mechanical reliability, less noise, and more patient comfort. Currently, third-generation devices using magnetically or hydrodynamically levitated, continuous-flow centrifugal pumps are at various stages of development.²

Ventricular tachycardia and ventricular fibrillation are common arrhythmias in patients with severe congestive heart failure and may be fatal if not treated immediately. We here report a case of asymptomatic sustained ventricular fibrillation over several hours with sufficient hemodynamics because of an implanted nonpulsatile-flow left ventricular assist device.