Vascular remodeling in cardiac allograft vasculopathy

Growing evidence suggests that vascular remodeling processes contribute significantly to the amount of luminal obstruction in coronary artery disease. Recently changes in vascular geometry in the form of positive (compensatory enlargement) as well as negative remodeling (constrictive changes) could be demonstrated in transplanted hearts as well. For further characterization intravascular ultrasound provides an excellent insight into time-related changes (by serial follow-up examinations) and into longitudinal spatial relationships within vessels (motorized pullback with 3-D reconstruction). Focused on time-related changes a decrease in total vessel volume within the first year after transplantation as compared to a slight compensatory enlargement in patients 'late' after HTX could be demonstrated. Regarding focal luminal obstruction, local constrictive changes (negative remodeling) were identified to be the most important predictor of severity of stenosis. It is concluded that changes in vascular geometry are of major importance in focal stenosis as well as in a general luminal loss of coronary arteries within transplanted human hearts. These observations might be of special interest regarding pathophysiology and potential therapeutic interventions in this unique form of an accelerated coronary syndrome.