Angiographic and angioscopic observations of the arterial luminal changes induced by vasospasm

Angiography and angioscopy were used to examine arterial luminal changes induced by experimental vasospasm. The right common carotid artery of the dog was perfused with Krebs-Henseleit solution at a constant pressure, 3,4-diaminopyridine (DAP), a selective potassium channel blocker was applied on the adventitia, and the luminal changes were observed with angiography and angioscopy. Angiographically vasospasm (defined as a reduction in the internal diameter to less than 50% of the control value) was always induced by the topical application of 5 X 10(-1) mol/L DAP. The internal diameter decreased to 25% +/- 7% (mean +/- standard error, n = 6) 15 minutes after the application. The vasospasms propagated 2.7 +/- 0.6 and 1.1 +/- 0.3 cm downstream and upstream, respectively. Angioscopy showed that the lumen narrowed gradually and concentrically. Perfusion of the artery during vasospasm for 15 minutes with a backflow of blood from the contralateral artery resulted in thrombosis at the spastic segment. The results indicate that carotid vasospasm can be constantly induced by DAP, thrombosis occurs in the spastic artery, and angioscopy is useful for serial observation of the luminal changes induced by vasospasm.