Abstract Body (Do not enter title and authors here): Background:
Innovations in left ventricular assist device (LVAD) technology have led to improved survival with less complications, however external outflow graft obstruction (EOGO) has been recognized as a new complication. EOGO occurs when fibrinous materials collect between the LVAD outflow graft, due to its porous nature, and bend relief cover. This collection compresses the graft and can cause low flow alarms and worsening heart failure. Consensus on management of EOGO has not been established. For patients with suspected EOGO, what diagnostic modalities should be utilized and what interventions should be considered?

Description of case:
A 54-year-old man with an LVAD was admitted for recurrent low flow alarms. Transthoracic echocardiogram (TTE) demonstrated a dilated left ventricle (LV) at 6cm, and ejection fraction of 21%. Computed tomography angiogram (CTA) showed stenosis in the proximal outflow graft near the pump housing. Endovascular approach, LVAD exchange, and graft repair were all considered, however he was listed for heart transplant. Prior to transplant, he developed cardiogenic shock with persistent low flow alarms. Repeat CTA showed extension of the outflow obstruction. He underwent mini thoracotomy, the space between the outflow graft and bend relief was fenestrated, and a yellow proteinaceous material gushed out. The outflow graft immediately expanded with improvement of LVAD flows.

Discussion:
EOGO should be considered in LVAD patients with recurrent low flow alarms. Multimodality imaging is vital to determine etiology and location of obstruction. On TTE, obstruction should be suspected if there is worsening LV dilation and mitral regurgitation. CTA is recommended as it allows visualization and localization of outflow graft obstruction. If obstruction is distal to the LVAD pump (near the aorta) endovascular approaches (stenting or balloon angioplasty) can be considered. If proximal to the pump housing, endovascular approaches may pose higher risk and surgery should be considered. Surgical interventions include relief of the obstruction by fenestrations in the bend relief, pump exchange, or even heart transplant. Given our patient's EOGO was proximal to the pump housing, endovascular approaches were not attempted. In summary, EOGO can be thoroughly evaluated with multimodality imaging including echocardiogram and CTA. CTA is imperative to evaluate severity and location of obstruction, guiding appropriate treatments strategies.