With this research study, we want to specifically study a group of patients who have chest pain or other signs or symptoms suggestive of heart disease but don't have visible blockages in the large heart arteries. Patients with chest pain who undergo heart catheterization but have no blockages of large heart arteries will be consented and enrolled. Patients will be asked to fill out questionnaires about their medical history, including family, reproductive and, social histories. They will also be asked to undergo testing during heart catheterization that would test for abnormalities in their small heart arteries using medications, acetylcholine and adenosine. This testing is a standard of care procedure given at the discretion of the treating physician. Patients would receive this test whether they participate in the research or not. The test is performed by infusing acetylcholine and adenosine through the same catheter that is used for routine heart catheterization. This test may add an additional 15 minutes to the heart catheterization procedure.