Comparison of CT Angiography With Conventional Angiography and Intravascular Ultrasound in Heart Transplant Patients

Inclusion Criteria:

1. Patient referred for coronary angiography and IVUS as part of their standard clinical care;
2. Patients must be 18 years of age or older.
3. Any ethnic background is acceptable.

Exclusion Criteria:

1. Patients with contraindications for the use of iodinated contrast (allergic reaction, renal failure, multiple myeloma, etc) will be excluded.

2. Patients with heart rate higher than 65 bpm and contraindications for the use of beta-blockers, listed below:

   Systolic blood pressure < 90mmHg Decompensated congestive heart failure; COPD or asthma in use of bronchodilator; Second or third degree heart block; Severe aortic stenosis, defined by a pressure gradient higher than 50 mmHg and/or the presence of symptoms.

3. Patients with contraindications for the use of nitroglycerin, listed below:

   Severe anemia; Increased intracranial pressure; Known hypersensitivity; Use of Sildenafil Citrate (Viagra®)

4. Children and pregnant women will be excluded because of risks associated with radiation exposure.
5. Patients must have no atrial fibrillation, as this will interfere with cardiac gating for the examination.
6. Patients unable to give informed consent will be excluded as well.
7. Patients with a coronary stent placed.