頸動脈狭窄症に対するPercutaneous Transluminal Angioplasty (PTA)の応用

PTAの血管拡張機序,合併症,長期成績に関する実験的研究

抄録

Percutaneous transluminal angioplasty (PTA) is not commonly applied to the carotid artery because of the risk of cerebral embolization and the uncertainty concerning the long-term results. To test its effectiveness and safety, the author performed PTA in dogs with experimentally induced carotid artery stenosis. Under general anesthesia, one carotid artery was exposed by midline incision. Two vascular tourniquets were applied to the artery, 2 to 5 cm apart, and the blood between them was replaced with pentobarbital sodium for 5 minutes. The drug was then removed and the tourniquets released. Angiography revealed the formation of stenotic lesions within 1 to 6 weeks. Histological examination showed the source of stenosis to be thrombi adhering to the vessel wall. PTA was performed 1 week or 3 to 6 weeks after induction of stenosis using either Grüntzig or Dotter catheters. Immediately after PTA, considerable enlargement of stenotic areas was angiographically observed, and no emboli were detected in distal arteries. Histological findings included depressions in the intima, thrombi, and stretching of the internal elastic membrane and tunica media. Angiograms obtained 3 and 6 months after PTA disclosed persistence of dilatation of the carotid lumen and diminution of the inner surface irregularities. Six months after PTA, the histological features included intimal proliferation and rarefaction of the tunica media. On the other hand, stenotic arteries not subjected to PTA were totally occluded by thrombi and intimal proliferation 6 months after induction of stenosis. It is apparent that PTA was effective not only in bringing about dilatation of the carotid artery but also in arresting the progression of stenosis. These results suggest that PTA would be effective in the treatment of carotid artery stenosis in humans.