左室病変を伴った不整脈源性右室異形成症と考えられる1例

Left Ventricular Lesions in a Patient with a Probable Diagnosis of Arrhythmogenic Right Ventricular Dysplasia

　左室病変を伴う不整脈源性右室異形成症（ARVD）と考えられる1例を経験した．ARVDの診断は，心エコー・右室造影で右室心尖部の心室瘤，内腔の拡張とびまん性の壁運動低下（駆出率；40％）を認めたことに基づいた．左室造影では内腔の拡張は明らかでなかったが，心尖部の壁運動低下と軽度の駆出率低下（55％）を認めた．²⁰¹Tl心筋シンチグラムでは，左室心尖部の他に同前壁・下壁で取り込み低下を認めた．左室心内膜心筋生検では軽度だが有意の線維症を認めた．文献的には，左室病変を合併したARVDの報告例は稀ではなく，左室心尖部・下壁・前壁において造影上の壁運動異常を認めている．この他，ARVDの左室病変の評価には，運動負荷心プールシンチグラムや安静時²⁰¹Tl心筋シンチグラムが用いられている．本例でも，壁運動低下を示さなかった左室前壁・下壁で有意の心筋シンチグラム所見を認めており，ARVDに伴う左室病変の検出における同検査法の有用性が示唆された．

We report a patient who had left ventricular (LV) abnormalities associated with arrhtymogenic right ventricular dysplasia (ARVD). This Japanese man had suffered from paroxymal supraventricular tachycardia (PSVT) since age 42. At age 51, episodes of PSVT became frequent despite antiarrhythmic medication, and mild LV dysfunction was noted by echocardiogra-phy (ejection fraction; 61%). He was then admitted to our hospital for cardiac evaluation. Cardiothoracic ratio was 50% on a chest x-ray film. An electrocardio-gram showed frequent ventricular premature contrac-tions and negative T waves in the precordial leads. Right ventriculography demonstrated the dilated and diffusely hypokinetic RV (ejection fraction; 40%) and a aneurysm of the RV apex. Left ventriculography showed almost normal wall motion (ejection fraction ; 55%) and mild hypokinesia of the LV apex. In radionu-clear myocardial imaging, thallium uptake was reduced in the anterior and inferior portions of the LV, where wall motion was normal, as well as in the apical por-tion. Although ARVD is believed to exclusively involve the RV, several previous studies have reported the LV abnormalities including focal hypo- or akinesia demon-strated by radionuclear or conventional contrast left ventriculography and perfusion defects visualized by radionuclear myocardial scanning. We believe that radionuclear myocardial imaging is very useful for detection of LV abnormalities in patients with ARVD.