Biomarkers for Cardiovascular Disease

Biomarkers for Cardiovascular Disease Summary: This study will examine the function of the lining cells of blood vessels and measure substances in the blood to see how they relate to various blood tests, including new tests under development to determine cardiovascular disease risk. Nitric oxide is a molecule produced by healthy blood vessels that helps keep them relaxed. Nitrate is a substance formed from nitric oxide in the blood. The release of nitric oxide by blood vessels is reduced in patients with coronary artery disease, compared with healthy people. Also, blood nitrite levels rise in some of these patients. Other substances in the blood and urine also change with risk for heart disease. This study will measure nitrite levels and other inflammatory substances in the blood and urine. Healthy volunteers, people with various risk factors for heart disease, and people with blockage of one or more major heart arteries or a history of heart attack may be eligible for this study. Candidates must be 21 years of age or older. People who have an irregular heart rhythm or who cannot take oral nitrates are excluded. Participants undergo the following tests and procedures: * Blood tests: Samples are drawn three times for routine tests and to look for certain proteins that may affect the heart. Samples are collected once before any other tests, once before starting the exercise stress test (see below) and again after the stress test. * Urine test: A sample may be tested for proteins in the urine and for other research studies. * Brachial artery reactivity study: This ultrasound study tests how well a person's arteries widen. The subject rests on a bed. An ultrasound measuring device is placed over the artery just above the elbow. The size of the artery and blood flow through it are measured before and after inflating a pressure cuff around the forearm. The pressure cuff stops the flow of blood to the arm for 5 minutes and then is released while more ultrasound picture