Case of Outflow Graft Obstruction from Extrinsic Compression in HM III LVAD

Introduction Pump thrombosis is an important adverse outcome to be aware of in patients with left ventricular assist devices (LVADs). While Heart Mate III (HMIII) has significantly lower rates of pump thrombosis, outflow graft obstruction remains a possibility. We present a case of outflow graft obstruction secondary to extrinsic compression at the site of the bend relief in a HMIII. Case Report A 36-year-old male with a history of non-ischemic cardiomyopathy status post HMIII as a bridge to transplant, with history of two LVAD pump exchanges due to pump thrombosis, presented with dyspnea and low flow alarms. Computed tomography (CT) of the chest demonstrated luminal narrowing with near obstruction of the outflow graft, concerning for thrombus. Urgent right heart catheterization demonstrated cardiogenic shock with elevated biventricular filling pressures. He was placed on Veno-Arterial Extracorporeal Membrane Oxygenation support and his listing status was upgraded to Status 1 for heart transplant. He was started on intravenous heparin for suspected pump thrombosis, and ultimately went on to transplant. With removal of the LVAD intra-operatively, proteinaceous material was noted between the bend relief collar and the outflow graft, leading to extrinsic compression of the graft, with no evidence of thrombus. Summary When evaluating patients with suspected outflow graft obstruction, it is important to consider not only pump thrombosis, but also the possibility of extrinsic compression of the outflow graft leading to obstruction. Distinguishing these etiologies is important as management may greatly vary.