Home Faculty and Staff Hospitals and Offices Education / Fellowships Make an Appointment
Keck School of Medicine of USC - University of Southern California
Department of Surgery
Department links
Home Physicians Locations Education Society of Graduate Surgeons Contact Us Divisions and Institutes
CardioVascular Thoracic Institute
image map
Areas of Expertise Diseases & Treatments Clinical Trials Research News & Articles Videos Web Links
Patient Guides & Programs Visitor's Guide Forms & Downloads About CVTI Make a Gift Contact Us

Women's Guide to Heart Health
Small Vessel Coronary Disease

About the Heart and Small Vessel Coronary Disease

The heart is a muscle that pumps blood throughout the body. Like other muscles, it needs oxygen and nutrients to function. The heart receives its oxygen and nutrients from blood pumped from a large blood vessel called the aorta, through smaller blood vessels called arteries (coronary arteries), then through even smaller vessels called arterioles and capillaries. The arterioles and capillaries are directly connected to the heart muscle (myocardium).

Small Vessel Coronary Disease

Small vessel coronary disease is a type of coronary heart disease (CHD) that affects the heart's arterioles and capillaries. Small vessel coronary disease is also known as Syndrome X, microvascular dysfunction, non-obstructive coronary disease, or microvascular angina.

Women are more affected by small vessel coronary disease than men. One reason for this may be due to estrogen (hormone) levels combined with other risk factors, such as high blood pressure.

How Small Vessel Coronary Disease Affects Blood Vessels

Healthy blood vessels normally expand (dilate) during exercise and other moments of physical or emotional stress. This , allows more blood to flow through and supply the body with oxygen and nutrients. Blood vessels that are affected by small vessel coronary disease do not function properly, and therefore do not dilate properly. Diseased small vessels may even contract, or get smaller, during physical stress. This results in reduced blood flow to the heart (ischemia). When this happens, chest pain (angina) or discomfort may happen.

Testing for Small Vessel Coronary Disease

Even though some patients may not have any obvious blockages in their coronary arteries, tests such as a stress exercise test can reveal signs of small vessel coronary disease.

Symptoms of Small Vessel Coronary Disease

Small vessel coronary disease and coronary heart disease (CHD) have similar symptoms, which can occur at any time, whether a person is resting, exercising or during moments of emotional stress. Symptoms include shortness of breath, chest pain (angina), sudden fatigue or weakness during exertion, and dizziness or lightheadedness.

Risk Factors

These risk factors may contribute to small vessel coronary disease. Some may be controlled or treated, while others cannot be changed.

Risk factors that may be controlled or treated to minimize or reverse the effect of small vessel coronary disease include:

  • Smoking and exposure to secondhand smoke
  • High LDL cholesterol levels ("bad" cholesterol)
  • Low HDL cholesterol levels ("good" cholesterol)
  • High blood pressure
  • High triglyceride levels
  • Stress or depression
  • Lack of exercise / inactive lifestyle
  • Overweight / obesity
  • Diabetes
  • Low estrogen levels in women

Risk factors that cannot be controlled or treated include:

  • Family history of heart disease
  • Aging
  • Gender: women have a higher risk of developing small vessel coronary disease than men

Other risk factors that may contribute to increased chances of small vessel coronary disease:

  • High levels of stress
  • Abnormal levels of homocysteine in the blood
  • Excessive alcohol use
  • Depression
  • Abnormal levels of lipoprotein
  • Abnormal levels of C-reactive protein
  • Abnormal levels of the Lp-PLA2 enzyme


Because small vessel coronary disease affects the heart's smaller vessels, it is more difficult to detect the condition using standard tests for the heart (angiogram, echocardiogram, stress exercise test). Specific tests for small vessel coronary disease include:

Electrocardiogram (ECG)

Electrocardiogram is a noninvasive test where electrodes are placed on the chest and the heart's electrical signals are measured to detect irregularities in the heart's rhythm and structure. This may helpindicate narrowed or blocked arteries.

Exercise Stress Test An exercise stress test is performed while a continuous electrocardiogram (ECG) is monitored to check for small vessel coronary artery disease. While the heart rate is increased with exercise on a treadmill, an electrocardiogram looks for arrhythmias and signs of narrowed arteries.

Positron Emission Tomography (PET)

Positron emission tomography is an imaging test to show the heart's blood flow and pumping function. During the test, the patient is injected with a radioactive material and then undergoes a scan of the heart.

Computerized Tomography (CT) Angiogram

Computerized tomography angiogram is a minimally invasive imaging test that checks the large arteries of the heart for narrowing or blockages. The patient, after being injected with a radioactive dye, lies down on the scanning table and is scanned by the CT scanner.

Cardiac Magnetic Resonance Imaging (MRI)

Cardiac magnetic resonance imaging is a noninvasive test that determines the structure and function of the heart. The patient lies down on a table inside a tube-like scanning machine, where a magnetic field and radio waves produce signals that create detailed pictures of the heart's myocardium and valves.

Coronary Angiogram

A coronary angiogram is an x-ray test to assess the coronary arteries for narrowing or blockage.A catheter is used to inject radio-opaque dye into the coronary arteries, which becomes visible on x-ray and fluoroscopy.

Endothelial Dysfunction Test

An endothelial dysfunction test is an invasive test that uses medication, injected through a catheter placed in the coronary arteries, to test blood flow and dilation of the endothelium. The endothelium is the thin layer of cells that line the interior surface of blood vessels.


The management of risk factors, including a healthy diet, exercise, and weight loss plan if necessary, are important in the treatment of small and large vessel coronary artery. Managing risk factors also help prevent additional complications, including heart attack or stroke. Other methods of managing risk factors include the properly controlleddiabetes, smoking cessation, and stress management and relaxation techniques.

Medication that may be necessary to further manage risk factors include blood pressure and cholesterol, medications as well as aspirin to thin the blood and prevent the formation of blood clots.

Additional medications may be prescribed to help with proper blood vessel function and to relieve angina symptoms. These may include ACE inhibitors, angiotensin receptor antagonists, nitroglycerin to relax large blood vessels and increase blood flow, and beta-blockers or calcium channel blockers to control chest pain.

Share this page:
Call us for an Appointment at (323) 442-5849
Women's Guide to Heart Health
Department of Surgery Home Divisions Physicians Locations Contact Us Education Society of Graduate Surgeons Keck School of Medicine of USC University of Southern California