強大な拡張期過剰心音を伴った無痛性解離性大動脈瘤の1例

A Case of Silent Dissecting Aneurysm Associated with Strong Diastolic Extra Sounds

　患者は60歳，男性．6年前，弓部嚢状大動脈瘤を指摘されている．9カ月前，重症三枝病変の診断でCABG施行．術後8カ月後，自覚症状はなかったが，新たに拡張期雑音と拡張期過剰心音を聴取し，胸部X線写真にて右第1弓の突出，胸部CTにて新たな上行部解離性大動脈瘤が確認された．経食道心エコー検査にて，大動脈弁直上にentrvをもつintimalflapが弁様に翻転するのが観察された．上行弓部大動脈置換術を施行し，術後過剰心音は消失した．本例における過剰心音は，収縮期に解離腔へ流入した血流が，拡張期に真腔および左室内へ流入する際に，intimal flapを弁様に翻転させ，拡張早期にHapと大動脈弁が接触するときに生じる衝突音および大動脈壁へ押し付けられ伸展したflapがもとに戻るときの反跳音であると考えられた．

　A 66-year-old man who had been diagnosed as saccular aneurysm of aortic arch six years ago, was admitted to our hospital for evaluation of angina pectoris andhe underwent coronary artery bypass surgery for severethree vesseles disease. Saccular aneurysm had no indication for surgery. Eight months later, though he had nosymptoms, diastolic regurgitant murmur and strongextra sounds, obviously different from third sound, werenewly audible. Sequential chest X-ray films revealedprogressive cardiomegaly and pleural effusion. Echocardiography and thoracic CT examinations revealed newascending aortic dissection (DeBakey type 2). Transesophageal echocardiography showed an intimal flap justabove the level of the aortic valve, fluttering like avalve. Phonocardiographic and echocardiographicfindings suggested that the diastolic extra sounds maybe caused by slapping motion of the intimal flap.