Inclusion criteria:

1. Heart transplant recipients undergoing annual cardiac catheterization who have participated our protocol: Characterization of brachial arterial t-PA release, vasodilator function, and vascular compliance and correlation with fibrinolytic balance, oxidative stress, and inflammation measures in heart transplant recipients (SCCOR Project 1, Aim 3C). (IRB # 070517)
2. 25 Subjects will have transplant vasculopathy and 25 subjects will be free of transplant vasculopathy, as documented in previous angiograms.
3. Otherwise healthy

Exclusion criteria:

1. PVC < 30
2. Hypertensive subjects on ACE inhibitors
3. Pregnant or nursing mothers
4. Diabetic with HbA1C > 7.5 or stigmata of end organ damage (neuropathy, retinopathy, nephropathy, cardiomyopathy)
5. Cholesterol > 30 mg/dL above NCEP accepted level based on cardiac risk.
6. Triglycerides > 200
7. Previously diagnosed obstructive coronary artery disease
8. Renal insufficiency (Creatinine ≥ 1.5 mg/dl)
9. History of cerebrovascular disease
10. Any chronic inflammatory disease (rheumatologic, inflammatory bowel disease, etc)
11. Uncontrolled Stage 2 Hypertension (160/100 mmHg), or end organ damage due to hypertension (left ventricular hypertrophy, atrial fibrillation, hematuria, renal insufficiency, prior cerebrovascular disease).
12. Angiotensin converting enzyme inhibitor use
13. Coagulopathy (INR ≥ 1.5, PTT ≥ 150% of control)
14. Peripheral Vascular Disease
15. Other chronic medical illnesses at the discretion of the investigators

Healthy controls are being enrolled in SCCOR Project 1, Aims 3A and 3B (IRB# 030473 and 061160) and will not be participating under this IRB number.