Diagnosis and Treatment Strategies of Outflow Graft Obstruction in the Fully Magnetically Levitated Continuous-Flow Centrifugal Left Ventricular Assist Device - A Multicenter Case Series

Abstract

Reports of pump thrombosis are less common for the HeartMate 3 than for other commercially available LVAD. However, blood flow obstructions of the inflow and especially of the outflow graft are likely to occur also with this device. A correct diagnosis is crucial for optimal treatment to ultimately avoid bail-out by (urgent) heart transplantation or unwarranted pump exchange. We present six cases of outflow graft obstruction (OGO) other than twist of the outflow graft under oral anticoagulation. We present detection principles and discuss treatment strategies. 1: 64 y/o, female, valvular heart disease, 21 months after implantation, presentation with multiple low-flow alarms. 50% OGO in CT scan. External cannula compression proximal of the LVAD outflow conduit in percutaneous angiography (PA). Re-thoracotomy, opening of the bend relief made of a reinforced PTFE graft, removement of hyaline thrombus, pump flow returned to normal. 2: 70 y/o, female, dilated CMP, recurrent low-flow alarms, high PI values. Consistently low flow in ramp study. Treatment of severe OGO in PA with two stents. Pump flow returned to normal. 3: 55 y/o, male. Presentation of acute angina pectoris, dyspnea. 75% OGO in CT scan. PA and implantation of two stents. Relief from clinical symptoms. 4: 37 y/o male, dilated CMP. Routinely admission for evaluation for heart transplantation (HTx). LVAD log files normal. Significant OGO in CT scan. PA confirmed OGO, but no relevant gradient pressure across the outflow graft, decision to "watchful waiting approach" and listing for HTx. 5: 67 y/o, male, dilated CMP. Presentation in a reduced general condition and slightly reduced pump flow. 70% OGO in CT scan. Pump flow increased to normal after intervention. 6: 56 y/o, female, ischemic CMP. Presentation with acute persistent low-flow alarms. 50% OGO in CT scan. Multiple hypodense areas in the infra- and supratentorial region as consequence of an embolic induced ischemic stroke. Despite emergency treatment the patient died on the same day. OGO in LVAD is a rare complication whose clinical presentation may be subtle. Three patients were successfully managed with stents, one underwent surgical revision, one patient died despite emergency treatment and the last patient without symptoms was listed for HTx.