VADoscopy: A novel intraoperative technique to evaluate heartmate II left ventricular assist device inflow obstruction and thrombosis

摘要

With HeartMate II (HMII) implants increasing so has the frequency of device exchange. However, identifying inflow cannula obstruction, pump thrombosis, or outflow obstruction as the mechanism of pump dysfunction can be difficult. Echocardiography, CT angiogram, and cardiac catheterization are not definitive in determining the location of pump failure. Therefore, intraoperative examination is often necessary to confirm a diagnosis, requiring extensive dissection to visualize the entire system. We hypothesized a novel intraoperative technique, VADoscopy, can evaluate the inflow cannula for thrombus or pannus formation, and can help guide decision on which portion(s) of the HMII require replacement. Visualization of the inflow cannula can determine if either the pump itself or the pump along with the inflow cannula requires replacement, potentially limiting unnecessary dissection around the left ventricular apex and inflow cannula. A subxiphoid or subcostal incision exposes the pump. Patients are placed on cardiopulmonary bypass using the femoral vein and artery, after the outflow cannula is clamped. Once the pump is removed from the pocket, a 22 French 80 cm(Edwards Life Science, Irvine, CA) Fogarty balloon is advanced through the inflow cannula into the left ventricle and inflated to limit blood flow from the heart. A 5 French 30 cm flexible endoscope (Karl Starz Flex-X, Germany) is then placed into the inflow cannula and left ventricle to evaluate for the presence of thrombus, pannus, or debris. Six patients had HMII exchange with VADoscopy. In all patients, VADoscopy demonstrated no inflow cannula pannus or thrombus as the cause of pump dysfunction. Postoperatively there were no embolic events or evidence of reoccurring pump dysfunction suggesting an inflow cannula obstruction was not missed. VADoscopy is a novel and effective operative diagnostic modality to evaluate the inflow cannula within the HMII left ventricular assist device, limiting the amount of dissection, and potentially reducing the morbidity associated with HMII pump exchange.