冠側副血行路の安静時と負荷時の役割について—左前下行枝一枝完全閉塞例での検討

Effect of coronary collateral vessels at rest and during atrial pacing stress test in complete occlusion of the left anterior descending coronary artery

　これまで虚血性心疾患における冠側副血行路の機能評価は数多くあるが，左心機能保持の有用性を肯定する報告^1,2）と否定的な報告^3）とが混在している。その主たる理由は側副血行の程度が，冠狭窄度に大きく左右されるため，対象症例自体の相違によると考えられる。したがって，側副血行の機能を評価する上で，側副血行を受けている冠動脈の狭窄度を一定の条件下におくことが重要であるが，条件設定下で側副血行の機能を検討したものは少なく，また乳酸代謝より側副血行の負荷時の役割を検討した報告は，調べた範囲では見当たらない。そこで，本研究では順行性血流の全く認められない左前下行枝完全閉塞例において，側副血行の定静時の機能と，局所乳酸摂取率を指標に右房ペーシング負荷時の機能を検討した。

The purpose of this study was to evaluate thefunctional importance and limitation of coronary collateral vessels. Eighty patients with complete occlusion of the left anterior descending coronary artery and 10 normal subjects (control) were selected. Patients were grouped into three classes, angina pectoris or anterior non-transmural myocardial in-farction (MI) with good collaterals (group A), an-terior transmural MI with good collaterals (group B), and anterior transmural MI without good col-laterals (group C).

The left ventricular ejection fractions at rest were group A (0.66±0.11)> group B (0.51±0.12)>group C (0.42±0.11), and the length of asynergy regions were group A (2.1±3.5 segments)<group B (9.0± 4.1)<group C (11.6± 3.0) (p<0.05).However, dur-ing atrial pacing stress test, ST-segmental depres-sion and negative myocardial lactate extraction ratio were shown in only good collaterals (group A and group B).

Thus, well grown coronary collateral vessels were effective to keep cardiac function at rest, but could not fulfill those function to protect myocardium from ischemic change during atrial pacing stress test.