Coronary Artery Vasculopathy in Pediatric Heart Transplant Patients

Early Detection of Coronary Artery Vasculopathy in Pediatric Heart Transplant Patients: A Prospective Assessment Using Coronary Flow Reserve and Contrast-Enhanced Cardiac MRI

Heart transplantation is a life-sustaining therapy that allows patients with either congenital or acquired heart disease and severe cardiac dysfunction to survive. Over time, however, the transplanted heart can develop problems. One of the more common and troubling problems is the development of stenoses, or narrowings, within the coronary arteries. These narrowings, technically referred to as coronary artery vasculopathy (CAV for short), account for the single most common cause of death or need for repeat heart transplant in persons more than one year post-transplant. Traditionally, CAV has been diagnosed at cardiac catheterization using coronary angiography (where dye is directly injected into the coronary blood vessels and viewed using special x-ray equipment called fluoroscopy). There is no good treatment for CAV aside from treatment of symptoms and listing for repeat heart transplantation. The goal of this study is to test several newer methods of diagnosing CAV. The first is called coronary flow reserve (catheterization test). The second is called Endo-PAT (a finger probe test) and the third is called contrast-enhanced cardiac MRI (MRI test, only for patients 12 and older). The older method (coronary angiography) will still be used in all cases, in addition to the new tests The goal is, one day, to be able to diagnose patients with CAV earlier in the course, prior to a patient's development of abnormal angiograms. If this can be done, it is possible that better therapies will be able to be used to stop or even reverse the development of CAV, perhaps reducing, or at least delaying, the need for repeat heart transplantation.

Inclusion Criteria:

• Patients age 1 - 25 years who are status-post OHT (≤18 years at the time of transplantation) and undergoing routine post-transplant surveillance catheterization for endomyocardial biopsy and coronary angiography

Exclusion Criteria:

• The presence of sick sinus syndrome or 2nd or 3rd degree atrioventricular block (without a functioning implanted pacemaker)
• Hemodynamically significant valvular disease
• Severe asthma or bronchospasm, known severe CAV
• Pulmonary hypertension.
• Patients taking digoxin
• Verapamil and dipyridamole are also excluded given known interactions with adenosine.