先天性内胸動静脈瘻の1例

A case of congenital arterioxvenous fistula of the internal mammary artery

　外傷性の内胸動静脈瘻の報告は比較的多数認められるが^1,2,3），大循環系における先天性動静脈瘻は胸部に発生することはまれで，とりわけ内胸動静脈瘻に関する報告は少ない^4）。

　本症は前胸部に連続性雑音を呈するため，動脈管開存をはじめとする心臓大血管系の異常に基づく雑音との鑑別に困難をきたすことがある^5）。

A patient with a congenital arteriovenous fistula of the internal mammary artery in a 24-year-old woman was described. She was admitted to our clinic for further evaluation of precordial heart murmur which was first pointed out while she was hospitalized for surgical treatment of her ovarian cysts.

On auscultation, a grade 3/6 continuous murmur was best heard at the fourth left intercostal space. There were no other abnormal physical findings.

Phonocardiogram revealed a continuous murmur of delayed onset which decreased in its intensity with amyl nitrite.

Chest x-ray film, electrocardiogram and echo-cardiogram and echocardiogram revealed no ab-normalities. Other laboratory studies were also within normal limits.

Patent ducats arteriosus, rupture of sinus of Valsalva aneurysm, and ventricular septal defect with aortic regurgitation were ruled out by phonocardiographic fingings and laboratory data. The patient was, then, thought to have a peripheral arteriovenous fistula near the chest wall, and cardiac catheterization was performed.

Coronary angiographm, left ventriculographm and pulmonary arteriography were all normal except that the left internal mammary artery and vein were connected in the distant portion, as found on the late film of aortic angiogram.

Congenital arteriovenous fistulas presenting continuous murmur in the precordial region may be confused with anomalies of the heart and great vessels, and careful phonocardiographic evaluation and angiographic studies were emphasised for differentiation in the origin of the murmur.