Percutaneous Stenting of LVAD Cannula Obstruction
Presenter
Harleen Chahil, MD, University of Louisville, Louisville, KY
Harleen Chahil, MD, University of Louisville, Louisville, KY and Vikas Singh, MD, FSCAI, Baptist Health Medical Group Cardiology, Louisville, KY
Title
Percutaneous Management of LVAD Obstruction
Introduction
Left ventricular assist devices (LVAD) have become a mainstay of advanced heart failure therapy. As LVAD technology has advanced and the average duration of support has increased, device durability has become essential to improve patient morbidity and mortality. We present a case of LVAD obstruction due to outflow cannula kink leading to thrombosis which was percutaneously managed. Clinical Case
60 year old male with history of CAD, hypertension, paroxysmal atrial fibrillation, and ischemic cardiomyopathy status post implantation of Heartmate II LVAD with subsequent pump exchange to Heartware for pump thrombosis was admitted for colonoscopy. During the procedure, he had an acute drop in his LVAD flows to 0.7L/min after an ingestion event. TEE showed depressed flow in the LVAD inflow cannula. He was given TPA due to concern for pump thrombosis He underwent LVAD exchange via the axillary artery and subcostal approach for a HeartMate II pump. However, after exchange he was noted to have flows of 2.7L at 2900rpm. CTA showed narrowing of the outflow tract near the anastomosis to the ascending thoracic aorta where there was thrombus almost completely occluding the outflow tract. He was brought to the cardiac catheterization lab for percutaneous intervention. The femoral artery was accessed under ultrasound guidance. 11F sheath was introduced and JR4 diagnostic catheter advanced over a Wholey wire into the LVAD outflow cannula. 6F pigtail was used to obtain a left ventriculogram showing the outflow from the LVAD which revealed a kink in the outflow cannula with narrowing and obstruction. An 8F 90 cm destination sheath was advanced into the outflow cannula and exchanged the Wholey wire for the Lunderquist wire. We used the Armada 35 5x40x135 and 12x40x135 to predilate the kinked portion of the cannula. With each inflation, the pump speed was turned down. We then stented it with a Viabahn VBX 11x39 mm balloon expandable covered stent followed by VBX 11x79 mm, VBX 11x59 mm, VBX 10x59mm and VBX 11x39mm with overlap and post dilated with the Z-MED 18x40mm balloon. 6F MP catheter was used for cineangiography of the outflow cannula and showed excellent results with excellent outflow from the LVAD into the aorta. LVAD flow improved to 4.8 LPM. The patient was started on clopidogrel and warfarin. Discussion
This is the first case reported with percutaneous management of LVAD obstruction due to kink in the cannula and thrombus formation. Pump thrombosis is the most common cause of pump failure with rates reported at up to 8-12%. Current management guidelines are comprised of surgical management with pump exchange in patients who are deemed to be surgical candidates or thrombolytics and direct thrombin inhibitors. However, given two previous sternotomies and recent surgery our patient was a poor surgical candidate and did not respond to thrombolytics. There are currently no trials to compare surgical versus percutaneous approach in these patients although case reports have been published. Further trials will be essential for incorporating the percutaneous approach into the management strategy for outflow graft obstruction in LVAD patients.