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Endothelial Function Test

The endothelium is the thin inner lining of the blood vessels. When the endothelium is healthy, blood flows smoothly.

If you live a sedentary lifestyle, eat a high-fat diet or smoke, your endothelium can become clogged with white blood cells and platelets, leading to heart disease and hardening of the arteries (atherosclerosis). This can lead to an increased risk of heart attack or stroke.

Endothelial cells release substances responsible for several functions in the circulatory system:

  • Blood vessel contraction
  • Blood vessel relaxation
  • Immune function
  • Blood clotting
  • Platelet adhesion

About the test

The endothelial function test is noninvasive. It is designed to measure blood flow through the arteries. The score that results from the test predicts your risk for heart disease.

The endothelial function test has two steps: 

1. Adenosine is injected into a coronary artery. This drug causes the blood vessels to open. The amount of blood flow is then measured.

2. Acetylcholine, which causes large arteries to open, is then injected. The amount of blood flow is measured again.

If the tests show decreased blood flow to the heart muscle, your physician may diagnose you with coronary microvascular disease and work with you to design a unique treatment plan.


  • External counter pulsation (ECP): During ECP, cuffs are placed around your thighs, hips and calves. The cuffs inflate and deflate in sync with the heart, giving extra oxygen-rich blood to the heart in the resting phase. More oxygen stimulates the growth of surrounding blood vessels, improving blood flow to the heart.
  • Lifestyle changes: When you are diagnosed with endothelial dysfunction, lifestyle changes are the first step in treatment. Your physician will recommend you adopt a heart-healthy diet and commit to regular aerobic exercise to keep the heart in shape. Healthy eating and regular activity will help reduce the risk of developing certain diseases, such as type 2 diabetes.
  • Medications: Your physician may also recommend medications, such as cholesterol-lowering drugs, alpha-beta blockers for high blood pressure and ACE inhibitors to treat high blood pressure and heart failure.
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