肺高血圧症を伴う心房中隔欠損症の冠動脈造影所見—主肺動脈による左主幹冠動脈の圧迫

Coronary arteriographic findings in the patients with atrial septal defect and pulmonary hypertension (ASD+PH):compression of left main coronary artery by pulmonary trunk

　冠動脈左主幹部（LMCA）の入口部狭窄は必ずしも稀な病変ではなく，次のような原因で起こり得る。すなわち，①動脈硬化^1,2），②大動脈炎症候群^3），③梅毒^4,5），④先天性冠動脈造影起始異常^6〜10），⑤先天性左冠動脈閉鎖^11），⑥川崎病^12）などである。今回我々は中等度以上の肺高血圧症を伴う心房中隔欠損症（ASD）において，病的な入口部狭窄を来たした例を経験した。その原因は著しく拡大した主肺動脈による冠動脈左主幹部の圧迫，圧排によると考えられた。てれは肺高血圧症における胸痛，失神発作の原因の1つである可能性もある。また，心房中隔欠損症の（術前）検査としての冠動脈造影の必要性も強調されるべきであろう。

　まず第一に，我々が肺高血圧症を伴うASDの冠動脈左主幹部が圧迫により狭窄を来たすことがあると考えるに至った発端の症例を呈示する。

The characteristic narrowing of left main coronary artery (LMCA) was found in 44% of patients (pts) with atrial septal defect and pulmonary hypertension (ASD PH). The cause of the narrowing is thought to be the compression by pulmonary trunk (PT).

Cardiac catheterization and coronary arteriography (CAG) were performed in 38 pts with ASD ranging in age from 15 to 62 years. We defined abnormal narrowing as 50% or more stenosis of AHA classi-fication. Sixteen pts (42%) had PH, and of these pts 7 show the abnormal narrowing of LMCA. (18% of all pts with ASD, 44% of pts with ASD+PH). They had no signs of syphilis or aortitis. Of the pts with PH, those with abnormal LMCA revealed higher pulmonary artery mean pressure than those with nor-mal LMCA (43.6±17.3 and 27.1±5.5 mmHg respe-ctively. p<0.01). Other parts of coronary arteries are intact in all pts. These findings suggest that the LMCA abnormality relates to PH.

In all cases with LMCA abnormality the narrow-ing revealed some special features indicate the cause of norrowing is compression. First, the most severe part of narrowing was the coronary ostium, and seve-rity reduced gradually as distal LMCA. Second, the narrowing was estimated most severely in the view of LAO 20, but almost normal in the view of RAO 30. This finding suggests the narrowing is ellipsoid. Third, the shape of LMCA changed in the different phase of cardiac cycle. In the systole, the cranial border of LMCA was convex, but in the diastole it was concave. This indicates LMCA was soft and compressed.

The autopsy of a patient with arteriographically subtotal occlusion of LMCA revealed completely patient LMCA and no findings of inflammation, scle-rosis or anomalous origin of LMCA.

We conclude the narrowing of LMCA in the pts with ASIDi PI-I is caused by compression by enlarged and high-pressured PT. Coronary arteriography is essential for the pts, with ASD+PH and, pts with severe narrowing may have to receive CABG.