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 arterial injury in experimental animals and has been used as the model system to investigate atherogenesis and restenosis after percutaneous transluminal coronary angioplasty (PTCA). The aim of this study was to examine the relationship between balloon inflation pressure and vascular damage and also subsequent intimal hyperplasia. Retrograde pullback balloon injury of rabbit aortas was made at three different balloon pressures (1.5, 1.75, and 2.0 atm). The medial injuries, such as necrosis of smooth muscle cells and disruption of elastic lamina, were occasionally 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 time, 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 parallel to the degree of inflation pressure. On the other hand, decrease of DNA content of the media and reduction of norepinephrine-induced vasoconstriction were observed in a pressure-dependent manner after balloon 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 vascular injuries, subsequent intimal hyperplasia and vasomotor responses in animal models of balloon catheter injury.