Vascular Remodeling and Neointimal Formation Depend on Stent Design in Small Coronary Arteries
Stenting of small coronary arteries is a complex issue that has been faced with problems of acute thrombosis and later restenosis. Small arteries present a distinct problem because there is a much greater proportional response to neointimal hyperplasia due to the already small diameters. These procedures have, however, been shown to be both effective and safe given proper training and procedure (Lau, 1997), and we now consider how factors such as stent design will affect vascular response within these small vessels. Four stent designs were implanted within the three major coronary arteries of swine hearts. All vessels were 3.0 mm in diameter or less. Morphometric and quantitative coronary analysis at 28 day follow-up showed that stents of a tubular design performed better than non-tubular designs by causing less intimal area, injury, and percent stenosis. Percent stenosis of non-tubular designs was 69% greater (p<0.000 1) and also resulted in consistently higher neointimal area and injury scores that were as much as two degrees higher than stents of a tubular design. We then were able to conclude that stent design has a considerable impact on vascular response when stenting small diameter arteries. Proceeding beyond design, we then focused on physical characteristics of the stents themselves while keeping factors such as design constant. There were three variations on the corrugated design that differed only in strut height and width. Changes in strut thickness effectively reduced the diameter of vessels by as much as 11 % (Solo) which had a thickness three times greater than the Multilink with an area reduction of 4%. This decreased vessel diameter resulted in greater shear rates of blood and contributed to enhanced platelet deposition. It was thus concluded that stenting of small diameter vessels produces the best results when using stents of a tubular design and that strut thickness should be kept to a minimum.