Abstract 4143715: An unusual cause for very early dysfunction of a bileaflet mechanical mitral valve (when push comes to shove)

Description of Case: A 44-year-old man with a history of mitral valve prolapse and mitral valve repair with triangular resection and partial annuloplasty ring placement eight years prior to presenting with dyspnea and decreased exercise tolerance. His TTE showed severe mitral stenosis with thickening of the posterior mitral leaflet. A redo sternotomy with mitral valve replacement was planned. Intra-procedurally, it was noted that the previous partial annuloplasty ring was impinging on the proximal portion of the posterior leaflet resulting in restricted motion, there was also fusion of the commissures. The partial annuloplasty ring was removed, and a 25 mm On-X mechanical valve was implanted in the mitral position. At the end of surgery, after the patient was off cardiopulmonary bypass, he developed severe hypoxia, and he was started on inhaled nitric oxide. Due to the concern for poor lung compliance, his sternotomy was not closed, and packing was placed in the anterior mediastinum and covered with an antimicrobial incise drape. In the surgical ICU, he became hypotensive and required ionotropic and vasopressor support. After diuresis, the surgical team decided to bring him back to the operating room on postoperative day 3 with concerns for mechanical valve dysfunction with the possibility of redo valve replacement in addition to closure of the anterior mediastinum and sternum. Intraoperative TEE showed that the anterolateral prosthetic mitral valve disc was fixed in the open position. There was no thrombus seen on the leaflets or the valve apparatus. On removal of the anterior mediastinal packing, the valve leaflet started functioning normally. The chest was closed without the need to redo the mechanical mitral valve. Discussion: Mechanical valve dysfunction can be either endogenous or exogenous. Our case represents a unique cause of early mechanical mitral valve dysfunction related to external compression by surgical packing impinging on the anterolateral disk inferior to the left atrial appendage from the ventricular side. Intraoperative TEE with 3-D played a vital role in the recognition of this complication and the prevention of redo valve replacement.