Thrombotic mitral valve obstruction during venoarterial extracorporeal membrane oxygenation with left ventricular venting following complex valve surgery

BACKGROUND: Left ventricular (LV) unloading during veno-arterial extracorporeal membrane oxygenation (VA-ECMO) is essential for managing refractory low cardiac output after complex cardiac surgery. However, direct LV venting is associated with an increased risk of intracardiac thrombosis, particularly when anticoagulation is delayed. CASE PRESENTATION: A 69-year-old woman with hypertrophic cardiomyopathy and severe left ventricular outflow tract obstruction presented with exertional dyspnea. Echocardiography showed severe mitral regurgitation with marked annular calcification, moderate aortic regurgitation, and systolic anterior motion of the mitral valve. She underwent complex cardiac surgery including septal myectomy, aortic and mitral valve replacement with bioprostheses, and tricuspid annuloplasty. Intraoperative rupture at the anterior mitral commissure required re-clamping, patch repair, and reimplantation of the prostheses. Prolonged cardiopulmonary bypass led to postoperative circulatory failure, necessitating VA-ECMO via the right axillary artery and femoral vein, with left ventricular venting through the right superior pulmonary vein. On postoperative day 4, ECMO was successfully weaned after recovery of contractility; however, the patient developed acute pulmonary edema and cardiogenic shock within hours, prompting urgent ECMO reinstitution. Transesophageal echocardiography on day 9 revealed thrombotic obstruction of the mitral bioprosthesis, confirmed intraoperatively. Both prosthetic valves and the left ventricle were covered with extensive white and red thrombi, which were completely removed. Cardiac function recovered after reoperation, and ECMO was successfully discontinued. Despite subsequent bilateral cerebral infarctions, the patient survived and was gradually weaned from mechanical ventilation at 1-month follow-up. CONCLUSION: Thrombotic complications in patients supported with VA-ECMO after valve replacement result from multiple interacting factors, including surgical trauma, prosthetic material, altered flow dynamics, and delayed anticoagulation. This case highlights the diagnostic challenges of assessing prosthetic valve function during VA-ECMO and underscores the need for individualized decisions regarding LV unloading strategies and anticoagulation management. Careful ECMO weaning and close echocardiographic surveillance may help reduce the risk of catastrophic valve-related complications.