Acute Pump Thrombosis Within 1 Hour Of Heartmate 3 Implantation.

Abstract

<h3>Introduction</h3> HeartMate 3 (HM3) and HeartWare (HVAD) are the most commonly used centrifugal Left ventricular assist devices (LVAD) in the current era. Pump thrombosis is a serious adverse event in LVAD patients. The earliest reported case of HM3 pump thrombosis was on the 3rd-day post-implantation. We present a rare case of pump thrombosis within the first hour of implantation. <h3>Case</h3> 39-year-old male with non-ischemic cardiomyopathy (LVEF 20-25%) was referred to our center for advanced heart failure therapies. He was transferred on milrinone 0.25 mcg/kg/min and urgent right heart catheterization was performed: RA 12, PA 46/30 with mean of 30, PCWP 30 mmHg, CO 3.17 L/min and CI 1.5 L/min/m². He was noted to be in cardiogenic shock with INTERMACS 2 profile. After multidisciplinary team discussion, urgent HM3 implantation was done. A thoracotomy and hemi-sternotomy approach was utilized. Before LVAD implantation, the LV cavity was examined and noted to be free of any clot. Heparin was reversed with standard protamine at the conclusion of cardiopulmonary bypass. No blood products or pro-coagulants were administered. Approximately 60 minutes after the end of the surgery, low flow alarms started. Intraoperative transesophageal echocardiogram was still in place and revealed no pericardial effusion or tamponade. Maneuvers including ramping speed and increasing dose of inotropes had no effect; the patient's right ventricular function was adequate, but his aortic valve could not be closed. After sternal reopening, the absence of tamponade was confirmed and there was no kinking of the outflow graft. <h3>Decision Making</h3> Given the acute persistent drop in pump flow despite the above corrective measures, there was a strong suspicion of pump thrombosis. Patient's chest was re-opened. The pump was unlocked from the sewing ring and inspected. The inflow cannula had fresh, nearly occlusive thrombus present (Figure 1). Thrombus involved all centered surfaces and also the outflow side of the pump. Pump exchange without reversal of heparin was performed. The pump was sent to the manufacturer for inspection. Histological analysis confirmed the pump thrombus. The patient's subsequent hypercoagulable workup was negative. <h3>Conclusion</h3> This case represents a unique instance of a very early pump thrombosis and should be kept in mind if new, low flow alarms are encountered immediately post-implant.