Case report
A 74 year-old male patient was referred to our department due to decompensated heart failure. He weighed 83 kg and his height was 178 cm, with a corresponding body surface area (BSA) of 2,01 m2. Relevant comorbidities included arterial hypertension, hyperlipidemia, severe pulmonary hypertension, atrial fibrillation and a previous ischemic stroke. The patient underwent a biological mitral valve (MV) replacement (Hancock, size 25 mm; Medtronic, Minneapolis, MN) 4 years prior to presentation for the treatment of symptomatic severe mixed mitral stenosis with regurgitation in another cardiac surgery department. At the time, the surgeon noted severe MAC that prevented insertion of a larger MV prosthesis. The geometric effective orifice area (EOA) of the Hancock valve prosthesis size 25mm is 1.46cm2 (1). This led to a severe PPM (EOA-index 0,72 cm2/m2) immediately after that initial operation. Two years later, the patient presented with rapid degeneration and stenosis of the MV prosthesis with severe symptoms (New York Heart Association (NYHA) class III). A transapical mitral ViV procedure (Sapien S3, size 23 mm; Edwards Lifesciences, Irvine, CA) was performed in the same cardiac surgery service, as a “last stage” measure to relieve symptoms. However, this led to a higher degree of PPM. Consequently, the patient re-presented to our department 2 years after transcatheter ViV replacement with severe dyspnea (NYHA IV) and peripheral edema. Transthoracic echocardiography revealed recurrent severe mitral stenosis (Pmax / Pmean 37/15 mmHg) and severe PPM (EOA-Index 0.32 cm2/m2), as well as markedly decreased right ventricular function and pulmonary hypertension (systolic PA pressure 45 mmHg). CT-scan revealed extensive mitral annular calcification (Figure 1 A - C ). Due to the ineffectiveness of conservative medical therapy and the patient’s wishes, we decided to perform a high-risk redo surgical MV replacement.
Surgery was performed through median sternotomy and with standard cannulation for cardiopulmonary bypass (CPB). Intraoperatively, both highly degenerated MV prostheses could be extracted (Figure 2 A - C ). Extensive annular decalcification was required to ensure implantation of an adequately sized MV prosthesis (Figure 2 D ). In order to prevent atrio-ventricular rupture as a result of the extensive decalcification, mitral annular reconstruction with a bovine pericardial patch was performed (Figure 3 ). A mechanical MV prosthesis (SJM Mitral Modell MJ-501, size 29 mm; Abbott, Chicago, IL) was thereafter implanted. Weaning from cardiopulmonary bypass (CPB) was not possible due to severe hypokinesia of the anterior left ventricular wall as evidenced in the intraoperative transesophageal echocardiography. It was hypothesized that a piece of calcium had embolized into the left coronary tree, since the preoperative cardiac catheterization ruled out significant coronary artery disease. Therefore, an aortocoronary bypass in beating heart technique (with CPB support) was performed to the left anterior descendent artery (LAD) using a saphenous vein graft. Thereafter, CPB could be successfully weaned. However, the thorax was left open due to a very dilated right ventricle as well as persistent hemodynamical instability. Cardiac catheterization was performed immediately after the operation, confirming calcium embolization with significant main left coronary occlusion. Proper function of the venous bypass to LAD could be observed, and the circumflex artery was stented. The patient developed low cardiac output syndrome thereafter, and an intra-aortic balloon pump was implanted. The patient developed progressive right heart failure thereafter with increasing catecholamine doses. Cardiac arrest subsequently occurred and a percutaneous arterio-venous extracorporeal life support (ECLS) was emergently implanted under mechanical cardiopulmonary resuscitation. One day later, the patient developed fixed and dilated pupils. CT scan revealed generalized cerebral edema with signs of brain herniation. Supportive measures were withdrawn shortly thereafter.