Endothelial dysfunction in heart transplanted patients with graft vasculopathy

Area of Science:

• Cardiovascular Research
• Transplantation Immunology
• Endothelial Biology

Background:

• The precise pathological mechanisms underlying cardiac transplant vasculopathy (TVP) remain incompletely understood.
• Endothelial dysfunction, specifically impaired release of endothelium-derived relaxing factor, is a potential contributor to TVP development.

Purpose of the Study:

• To investigate the hypothesis that endothelial function is compromised in patients with angiographic evidence of TVP.
• To assess the role of endothelium-dependent vasodilation in the pathogenesis of TVP.

Main Methods:

• Pilot studies evaluated the effects of substance P, acetylcholine, and nitroglycerin on human coronary arteries in vitro.
• Intracoronary infusions of substance P and acetylcholine were used to measure flow velocity changes in transplanted hearts via Doppler catheter.
• Coronary flow velocity and diameter were assessed in patients with and without TVP following intracoronary injections of substance P, nitroglycerin, and papaverine.

Main Results:

• Substance P demonstrated pure endothelium-dependent dilation in vitro.
• Both substance P and acetylcholine increased coronary flow velocity in transplanted hearts.
• Patients with TVP exhibited significantly reduced flow velocity increases in response to substance P and near-abolished flow-mediated vasodilation to papaverine compared to controls.

Conclusions:

• TVP is associated with significant endothelial dysfunction.
• Impaired endothelial function may play a crucial role in the pathogenesis of TVP and its associated vascular complications.