Prospective L-arginine Study

Effect of Chronic Oral L-arginine Supplementation on Peripheral Endothelial Function and Exercise Tolerance in a Population of Young Heart Transplant Patients.

HYPOTHESIS The investigators primary hypothesis is that peripheral endothelial function and exercise tolerance will be abnormal in the population of young heart transplant patients at baseline, and that each will show a trend towards improvement following a 12 week course of oral L-arginine, with regression towards the baseline following the 12 week washout period.

Inclusion Criteria:

• University of Michigan Pediatric Heart Transplant Clinic patient.
• Greater than or equal to 8 years of age.
• Heart transplant between 1 and 8 years prior to enrollment in the study

Exclusion Criteria:

• Relative hypotension for age
• Refusal to participate
• Inability to cooperate with Endo-PAT testing
• Pregnant or nursing women.
• Insulin dependent diabetes