Left Ventricular Assist Device Outflow Graft Obstruction Caused by Extrinsic Compression

Abstract

<h3>Introduction</h3> Left ventricular assist device (LVAD) outflow graft obstruction is a rare, but serious complication. A polytetrafluoroethylene (PTFE) graft covering has been used by some surgeons to reduce the frequency of adhesions and risk upon re-entry to the chest. Extra-luminal accumulation of material into the space between the graft and PTFE covering is one extremely rare cause of external compression and outflow graft obstruction. <h3>Case Report</h3> A 49-year-old male with a history of heart failure status post HeartWare LVAD with pump exchange one year previous due to thrombosis presented with a low flow alarm. His normal LVAD parameters were Flow 5.8 LPM, speed 3000 RPM, and power 6 Watts (W). On interrogation, he had a drop in flow to 2 LPM and power to 4 W beginning two days prior to presentation. Lab work was inconsistent with acute anemia, thrombosis, or hemolysis. Computed tomography angiography of the chest demonstrated outflow graft narrowing. He was taken to the OR for exploration which revealed accumulation of thick, proteinaceous material had accumulated between the outflow graft and the PTFE covering causing external compression and flow limiting stenosis. After removal of the external covering and relief of the obstruction, his flows increased from 2 to 6 LPM and power from to 4 to 6 W. <h3>Summary</h3> Evaluation of LVAD alarms can be difficult. Upon review of labs and imaging, an extraluminal compression of the outflow graft was suspected. LVAD outflow obstruction is a rare, but serious complication. One cause is accumulation of proteinaceous material between the semipermeable graft and the impermeable PTFE covering thought to be derived plasma contents. There is no consensus on treatment. Case series suggest percutaneous stenting or pump exchange. Surgical intervention can provide immediate relief of this problem.