外巻き生体弁移植後早期の人工弁機能不全の2例

Early Structure Valve Deterioration after Aortic Valve Replacement with the Externally Mounted Bioprosthetic Valve （Trifecta）：Report of Two Cases

はじめに　近年の対象患者の高齢化に伴い，大動脈弁置換術（aortic valve replacement：AVR）の生体弁使用の頻度は増加傾向にある．生体弁は術後抗凝固療法を必要とせず，患者の生活の質（QOL）を良好に保つことができるが，一方で機械弁より弁口面積が小さいことや，長期耐久性に劣ることが問題としてあげられる．

Trifecta valve is made from single bovine pericardial sheet, which is externally mounted on a titanium stent. This valve design provides good hemodynamic performance and wide effective orifice area. However, there have been some reports of early structural valve dysfunction which caused acute heart failure.

Case 1：An 80-year-old man who had undergone aortic valve replacement （AVR） using Trifecta 21 mm five years ago. He presented with fever and diastolic murmur. Echocardiography showed prosthetic valve regurgitation, and the patient later developed prosthetic valve endocarditis.

Case 2：An 80-year-old woman who had undergone AVR using Trifecta GT 21 mm two years ago developed sudden chest pain and dyspnea, prosthetic valve regurgitation. Both patients underwent re-AVR with a new bioprosthetic valve via re-sternotomy. Large tear was found in the right coronary cusp of the Trifecta in both cases. During Trifecta accomodation, we should avoid oversizing, and check the position of coronary ostia and sinus of Valsalva. Secure late outcome of Trifecta GT remains unproven and its use still needs caution.