Effects of stenting on adjacent vascular distensibility and neointima formation: role of nitric oxide.
Intravascular stents increase long-term patency but their effects on the vascular mechanics of adjacent segments have not been studied. In this study, stents were deployed in the rabbit abdominal aorta after 1 week of normal diet, 1% cholesterol diet or 1% cholesterol diet with L-nitro arginine (L-NA 60 mg/l water). Intravascular ultrasound showed a small distal decrease in vessel distensibility (area/pressure * 100) before stenting. Distensibility was almost abolished by stenting (0.12 +/- 0.01, p < 0.001), but was increased proximal to the stent and decreased distal to the stent both acutely (proximal: 1.18 +/- 0.10 vs distal: 0.65 +/- 0.06, p < 0.001), and at 4 weeks (proximal: 1.05 +/- 0.08 vs distal: 0.37 +/- 0.07, p < 0.001). Nitric oxide (NO) activity was enhanced proximal to and within the stent, and remained constant distal to the stent, (versus control, proximal: 57 +/- 23%, stent: 136 +/- 35%, distal: 2 +/- 12%, p < 0.01). The I/M ratio was significantly higher proximal to and within the stent than in the distal segment (proximal: 0.40 +/- 0.10, stent: 0.37 +/- 0.12, distal: 0.12 +/- 0.11, p < 0.01). NO blockade with L-NA prevented hyperdistensibility proximally, and significantly increased the I/M ratio within the stent and distally (stent: 0.81 +/- 0.19, distal: 0.30 +/- 0.10, p < 0.05) but not proximally (0.38 +/- 0.09). In conclusion, aortic stenting increases proximal vascular distensibility and intimal lesion formation. Nitric oxide blockade augments intimal growth within but not proximal to the stent.
Schwarzacher
S P
SP
University of Innsbruck School of Medicine, Division of Cardiology, Innsbruck, Austria.
Tsao
P S
PS
Ward
M
M
Hayase
M
M
Niebauer
J
J
Cooke
J P
JP
Yeung
A C
AC
D000818:Animals; D001011:Aorta / Q000473:pathology; D006439:Hemodynamics / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D009569:Nitric Oxide / Q000502:physiology*; D011817:Rabbits; D012016:Reference Values; D015607:Stents; D017539:Tunica Intima / Q000473:pathology / Q000502:physiology*; D017540:Tunica Media / Q000473:pathology; D014666:Vasomotor System / Q000503:physiopathology*
D009569:Nitric Oxide