Features of cardiac allograft coronary endothelial dysfunction

Nitric oxide-mediated coronary flow regulation in patients with coronary artery disease: recent advances

Nitric oxide (NO) formed via endothelial NO synthase (eNOS) plays crucial roles in the regulation of coronary blood flow through vasodilatation and decreased vascular resistance, and in inhibition of platelet aggregation and adhesion, leading to the prevention of coronary circulatory failure, thrombosis, and atherosclerosis. Endothelial function is impaired by several pathogenic factors including smoking, chronic alcohol intake, hypercholesterolemia, obesity, hyperglycemia, and hypertension. The mechanisms underlying endothelial dysfunction include reduced NO synthase (NOS) expression and activity, decreased NO bioavailability, and increased production of oxygen radicals and endogenous NOS inhibitors. Atrial fibrillation appears to be a risk factor for endothelial dysfunction. Endothelial dysfunction is an important predictor of coronary artery disease (CAD) in humans. Penile erectile dysfunction, associated with impaired bioavailability of NO produced by eNOS and neuronal NOS, is also considered to be highly predictive of ischemic heart disease. There is evidence suggesting an important role of nitrergic innervation in coronary blood flow regulation. Prophylactic and therapeutic measures to eliminate pathogenic factors inducing endothelial and nitrergic nerve dysfunction would be quite important in preventing the genesis and development of CAD.

The usefulness of chronic heart failure treatments in chronic cardiac graft failure

Following cardiac transplantation, registry data has demonstrated a gradual improvement in survival over the last several decades, which is testament to continual improvement in aftercare strategy. However, a significant number of patients will eventually develop a new syndrome of chronic heart failure, owing to the multitude of physiological processes that occur after transplantation. This condition, referred to as chronic graft failure (CGF) should be regarded as a unique illness rather than one that is simply analogous with chronic heart failure. In particular, the unique pathophysiological (and pharmacological) environment in the setting of CGF presents a challenging situation to the transplant physician. There is uncertainty over which treatments to offer given a paucity of clinical trial data to support the use of standard heart failure treatments in CGF. In this review, we discuss which chronic heart failure treatments could be considered in the setting of CGF based on their mechanisms of action, benefits within the native heart failure setting, and the relevant issues within the posttransplant environment.