On-X弁による僧帽弁置換術

Mitral Valve Replacement with the On-X Valve

On-X弁（On-X Life Technologies社，Austin）は，構成素材を含めて設計の段階から人工弁機能，耐久性，抗血栓性などの向上を図った人工弁で，その良好な臨床成績が報告されている1～4）．われわれは，On-X弁を用いて僧帽弁置換術（MVR）を3例に施行し，最長10年の経過を観察することができた．また，うち2例においては術後慢性期に不慮の事故による外傷性合併症を経験し，興味深い経過を認めたので報告する．

This is a 3-case report of mitral valve replacement （MVR） with an On-X mechanical valve followed up to 10 years. Case 1（64-year-old man） and case 2（66-year-old woman） experienced traffic accident and traumatic event, respectively, in their chronic phase after MVR. Case 1 had multiple bone fractures of the bilateral lower limbs, which was followed by systemic infection and pyogenic spondylitis. He needed long-term antibiotics therapy for more than 4 years. Case 2 fell down at home and severely hit her head, which resulted in a traumatic subarachnoid hemorrhage. She was in a deep coma, and needed discontinuation of anticoagulation therapy for 4 weeks. Case1, 2, and 3（54-year-old man） are doing well in New York Heart Association functional class I without any valve-related thromboembolic or hemorrhagic events at 10, 9 and 8 years after MVR, respectively. On-X valve performance has also been found well maintained in all cases by echocardiography, even after traumatic accident or discontinuation of anticoagulation in Case 1 and 2. In this report, the On-X mechanical valve demonstrated good mid-term result of its valve performance in the mitral position and its potential advantages in antithrombogenicity.