Pathophysiology
Clinical meaning
A left ventricular assist device (LVAD) is a mechanical circulatory support device implanted in patients with advanced heart failure (typically NYHA Class IIIB-IV with ejection fraction less than 25%) as either a bridge to heart transplantation or destination therapy. The device consists of an inflow cannula inserted into the left ventricular apex, a pump housing containing a magnetically levitated or hydrodynamically suspended impeller that propels blood, and an outflow graft anastomosed to the ascending aorta. A percutaneous driveline exits through the abdominal wall connecting the pump to an external controller and power source (batteries or AC power). LVAD thrombosis occurs when blood clot forms within the pump mechanism, on the inflow or outflow cannulas, or on the impeller itself. The blood-device interface activates the contact activation pathway of coagulation (factor XII, prekallikrein, high-molecular-weight kininogen) because the device surfaces lack the natural endothelial anticoagulant properties (thrombomodulin, prostacyclin, nitric oxide). Additionally, the non-physiological flow patterns (shear stress, stagnation zones) activate platelets and damage red blood cells (mechanical hemolysis). When thrombus forms on or around the impeller, it impedes the rotor's movement, causing...