Failure Of An Implantable Left Ventricular Assist Device: A Distinctive Electrocardiographic Pattern Before Malfunction

Long-term implantable left ventricular assist devices (LVADs) have revolutionized the care of patients with heart failure who are awaiting transplantation. 2 The HeartMate Vented Electric (VE) (Thermo Cardiosystems Inc., Woburn, Mass.) Left Ventricular Assist System (LVAS) consists of an implanted LVAD with a percutaneous drive line that connects the internal pump to the external power supply and controller, as well as providing a vent for the internal chamber to the atmosphere. The system is capable of supplying full circulatory support for the left ventricle and is currently being evaluated both as a bridge to transplantation and as a permanent alternative to transplantation in patients with irreversible heart failure. We report a case of primary pump failure that was heralded by a distinctive pattern on the electrocardiogram (ECG). Although device-related failures with currently available implantable LVADs have been extremely uncommon, we believe the ECG findings described, which occurred before device failure, may serve a predictive function and thereby avoid a catastrophic outcome. Clinical summary. The patient was a 60-year-old man who had an acute anterior wall myocardial infarction approximately 4 months before evaluation at our institution. Despite timely thrombolytic therapy and urgent coronary balloon angioplasty of an occluded left anterior descending coronary artery, the infarction progressed and the patient was left with severe residual left ventricular dysfunction, with an estimated left ventricular ejection fraction of approximately 20% by radionuclide ventriculography. After his referral to our institution, he was rehospitalized on two subsequent occasions for decompensated heart failure, which was responsive only to parenteral inotropic agents and diuretics. Despite aggressive medical support, his hemodynamic status continued to deteriorate and he was listed for heart transplantation. Seven months after the infarction, right heart catheterization revealed the following pressures while the patient was maintained on a continuous milrinone infusion: right atrium 8 mm Hg, pulmonary artery 75/39 mm Hg (mean 55 mm Hg), pulmonary artery wedge 40 mm Hg, cardiac index 1.3 L z min z m, and systemic blood pressure 75/50 mm Hg. The patient was judged to have heart failure refractory to maximal medical therapy and the decision was made to proceed with implantation of an LVAD as a bridge to transplantation. The patient’s blood type was O1 and the preoperative panel reactive antibody level was 68%. The device was implanted in the standard fashion with the LVAD positioned in a preperitoneal subcostal pocket with the inflow catheter placed in the left ventricular apex and the outflow graft anastomosed to the proximal ascending aorta. The combined power and control cable exited percutaneously above the left iliac crest in the left lower quadrant of the abdomen. The postoperative course was unremarkable and the patient quickly resumed his preoperative activity level with physical therapy. Anticoagulation consisted of 325 mg of aspirin per day. LVAD flow rates remained at 5 to 6 L/min off all cardiac medications. Renal and pulmonary function remained normal. On postoperative day 82, the patient reported a vague feeling of generalized uneasiness, and the LVAD flow rates indicated on the external console demonstrated a decrease to approximately 3 L/min. Systemic blood pressure remained within normal ranges. An intravenous bolus of normal saline solution was administered, after which the LVAD flow rates returned to baseline and the patient’s symptoms transiently resolved. A 12-lead ECG was obtained (Fig. 1). Approximately 45 minutes later, the patient became acutely unresponsive with minimal meaFrom the Departments of Cardiovascular-Thoracic Surgery, Cardiology, and Pathology, Rush-Presbyterian-St. Luke’s Medical Center, Chicago, Ill.