Temporary Left Ventricular Unloading With Impella as a Bridge to Emergency Surgery for Acute Mitral Bioprosthetic...

Structural valve deterioration usually declares itself gradually, but a bioprosthetic leaflet that tears away from a stent post can produce catastrophic regurgitation without warning. In the mitral position, the left atrium has not had time to become compliant, and the resulting rise in pulmonary capillary pressure can flood the lungs within hours. A 68-year-old woman who had undergone mitral valve replacement with a bovine pericardial bioprosthesis 13 years earlier developed sudden dyspnea. Her oxygen saturation was 58%, the chest radiograph showed almost complete bilateral opacification, and the pH was 7.042 with a lactate of 8.8 mmol/L. She was intubated after noninvasive ventilation failed. Catheterization excluded coronary disease and showed a cardiac index of 1.32 L/minute/m², a mean pulmonary artery pressure of 35 mmHg, and a wedge pressure of 22 mmHg. Echocardiography demonstrated severe regurgitation through the prosthesis with an abnormally mobile leaflet. Emergency surgery was indicated, but the operating room was occupied, and a wait of several hours was expected. With the pulmonary artery pressure rising, an Impella CP (Abiomed, Danvers, MA) was implanted approximately 11 hours after arrival and supported the circulation for five hours until cardiopulmonary bypass was established. During that interval, the rise in pulmonary artery pressure did not continue; the cardiac index and mixed venous oxygen saturation increased, and oxygenation was maintained despite a reduction in the fraction of inspired oxygen. Mean pulmonary artery pressure nevertheless remained approximately 40 mmHg. One leaflet was found torn away from a stent post and prolapsing into the left atrium; the valve was replaced with a porcine bioprosthesis. Postoperatively, she required hemodiafiltration for acute kidney injury and temporary pacing for bradyarrhythmia; the course was further complicated by small cerebral infarcts and a right phrenic nerve palsy. She was extubated on day 10 and discharged home on day 48, remaining in New York Heart Association class I at review on day 108. When definitive surgery for acute left-sided valvular failure must be delayed for logistical reasons, temporary left ventricular unloading may be considered as a means of protecting the lung during the wait. In this patient, it was associated with maintained oxygenation and improved systemic hemodynamics, although its independent contribution cannot be determined from a single case.