EFFECTS OF INFLATION PRESSURE OF BALLOON CATHETER ON VASCULAR INJURIES AND SUBSEQUENT DEVELOPMENT OF INTIMAL HYPERPLASIA IN RABBIT AORTA

Balloon catheter de-endothelialization is the most popular means of ar terial injury in experimental animals and has been used as the model s ystem to investigate atherogenesis and restenosis after percutaneous t ransluminal coronary angioplasty (PTCA). The aim of this study was to examine the relationship between balloon inflation pressure and vascul ar damage and also subsequent intimal hyperplasia. Retrograde pullback balloon injury of rabbit aortas was made at three different balloon p ressures (1.5, 1.75, and 2.0 atm). The medial injuries, such as necros is of smooth muscle cells and disruption of elastic lamina, were occas ionally found in the injured segment of the aorta by balloon catheter at 1.75 atm and more frequently at 2.0 atm. No prominent medial injury was observed in the aortic segment to balloon catheter injury at 1.5 atm; Intimal hyperplasia developed in each animal and increased with l ime, 2, 4, and 8 weeks after injury. The intimal hyperplasia followed by balloon injury at 1.75 and 2.0 atm was more prominent than that at 1.5 atm, however, the development of the intimal hyperplasia was not p arallel to the degree of inflation pressure. On the other hand, decrea se of DNA content of the media and reduction of norepinephrine-induced vasoconstriction were observed in a pressure-dependent manner after b alloon injury. These findings indicate that intimal hyperplasia is not proportionally correlated to the severity of the vascular injury. The control of inflation pressure is very important in order to examine v ascular injuries, subsequent intimal hyperplasia and vasomotor respons es in animal models of balloon catheter injury.