遺伝性QT延長症候群が心筋炎を契機に発症した1例

A Case of Setting of Acute Myocarditis Revealed Congenital Long QT Syndrome

　遺伝性QT延長症候群に心筋炎が合併し，多彩な不整脈が出現した症例を経験した．失神発作のため入院．入院時には完全房室ブロックで一時ペーシングを施行したが，房室ブロック回復後，血清CPKの遊出を伴う著しいQT間隔の延長を認め，心室頻拍を繰り返した．病態の安定後，これら諸病態の検索を行った結果，QT延長の既往歴・家族歴があり，心筋生検では心筋炎を示唆する所見が得られ，さらにカテコラミン負荷試験では著しいQT延長とtorsade de pointesが誘発された．本例は遺伝性QT延長症候群が心筋炎の発病を契機に発症したもので，Jackmanらの分類によるadrenergic依存性QT延長と考えられる病態を呈し，心室性不整脈の抑制にはβ遮断薬の投与とペースメーカ使用が有用であった．

We report a 68-year-old female patient with congeni-tal long QT syndrome (LQTS), who developed a variety of arrhythmias in the setting of acute myocarditis. She had been shown to have QT prolongation. Her sisters and daughters also have been shown to have QT prolon-gation. When she was admitted to our hospital because of acute myocarditis (proved by cardiac enzyme release and myocardial biopsy), she developed in spite of ventricular pacing, complete AV block and a variety of polymorphic ventricular tachycardia which was resis-teant to anti-arrhythmic agents.

Following recovery from acute myocarditis, we con-ducted programmable ventricular stimulation, but VT was not induced. Upon Adrenalin challenge, 9, her QT interval was prolonged, then torsades de pointes appear-ed, which developed into ventricular fibrillation. Shewas treated with a dual chamber pacemaker and βblocker successfully.