Contrast HyperemiaによるA-Cバイパス術のグラフト局所流量の評価

Evaluation on regional myocardial blood flow by contrast hyperemia after aorto-coronary bypass surgery

　A-Cバイパスグラフトの手術効果は臨床症状の改善^1）や左室機能の面^2）より明らかにされている。しかしながらバイパスグラフトそのものの冠血流に及ぼす影響についての検討はいまだ少ない。以前より造影剤を冠動脈に注入すると，contrast hyperemiaとして造影剤注入領域の冠動脈血流量が一時的に増加する^3）ことが明らかにされている。そこで今回A-Cバイパス術後の心臓カテーテル検査時にバイパスグラフト造影を行い，cont—rast hyperemiaとしての冠血流量の増加を冠静脈洞血流量の増加より測定し，バイパスグラフトの冠予備能に対する局所効果について検討した。

It has been demonstrated that the injection of contrast medium into the coronary artery or bypass graft causes a significant increase in coronary flow. This increase in contrast hyperemia causes by vaso-dilation of the regional coronary artery.

In this study, the restoration of coronary vascular reserve was evaluated in patients with aorto-coronary bypass surgery. Five patients undergoing aorto-coronary bypass surgery were studied. There were 5 men, aged 38 to 70 years (mean 53). Webster thermodilution catheter was introduced into the coro-nary sinus for measurement of coronary sinus flow. Resting coronary sinus flow was recorded. A hand injection of 4 to 6 ml of 76 percent Urografin was performed into the right, left coronary artery and bypass graft to obtain the hyperemic coronary sinus flow (coronary vascular reserve). No significant change in coronary sinus flow measured in response to the right coronary injection (from 94.8±20.7ml/min to 105.8±26.1ml/min) or bypass graft injection to the right coronary artery (from 106.0±21.2ml/min to 111.0±20.1ml/min). This can be explained by the fact that most of the venous flow from the right coronary artery returns in such a way that it cannot be measured by the coronary sinus catheter. In contrast, the mean coronary sinus flow in five patients increased from 95.8±15.1ml/min to 166.0±27.4ml/min by the injection to the left coronary artery (p<0.05). The mean coronary sinus flow by contrast hyperemia in 4 bypass grafts to the anterior descending and in 1 to the circumflex also increased from 103.2±13.1 ml/min to 146.0±28.2 ml/min (p<0.05).

These data suggest that the measurement of coro-nary sinus flow by contrast hyperemia may be useful to estimate the regional coronary vascular reserve contributed by bypass grafts after aorto-coronary bypass surgery.