How Is Hypotension Diagnosed?

Hypotension is diagnosed using a medical history and physical exam to find out:

• The type of low blood pressure and how severe it is
• Whether an underlying condition is causing the low blood pressure

Specialists Involved

Depending on the type of hypotension, it might be diagnosed and treated by a primary care doctor, or specialists may be involved, especially for the treatment of shock. The type of specialist most commonly involved is a cardiologist. A cardiologist is a doctor who diagnoses and treats heart diseases. Other specialists, including surgeons, nephrologists (kidney specialists), neurologists (brain and nerve specialists), and others may be involved.

Diagnostic Tests and Procedures

If a person is in shock, emergency action is required to find the cause and treat the shock. For other types of hypotension, the doctor may order the following tests:

• Tilt table test. This test is used if you have fainting spells for no known reason. You lie on a table that moves from a lying down to an upright position. The doctor checks your reactions to the change in position. The test can be used to diagnose orthostatic hypotension and neurally mediated hypotension (NMH). People who have NMH usually faint during this test. The test can help the doctor identify any underlying neurological condition.
• Blood tests. These tests can show whether anemia (low red blood cell count) or low blood sugar is causing the hypotension.
• EKG (electrocardiogram). This test measures the rate and regularity of the heartbeat.
• Portable EKG monitoring. Wires are attached to your chest with sticky patches and connected to a small battery-operated recorder.
  • A Holter monitor records all the heart's electrical activity for 24 hours.
  • An event monitor records selected periods of the heart's electrical activity. You may use this monitor for 1-2 months. When you feel symptoms, you press a button and the device records the heart's electrical activity. The information can be sent over the telephone to the doctor.
• Echocardiogram. This test uses sound waves to create a moving picture of your heart. Echocardiogram provides information about the size and shape of your heart and how well your heart chambers and valves are functioning. The test also can identify areas of poor blood flow to the heart, areas of heart muscle that are not contracting normally, and previous injury to the heart muscle caused by poor blood flow.
• There are several different types of echocardiograms, including a stress echocardiogram. During this test, an echocardiogram is done both before and after your heart is stressed either by having you exercise or by injecting a medicine into your bloodstream that makes your heart beat faster and work harder. A stress echocardiogram is usually done to find out if you have decreased blood flow to your heart (coronary artery disease).
• Stress Test. Some heart problems are easier to diagnose when your heart is working harder and beating faster than when it's at rest. During stress testing, you exercise (or are given medicine if you are unable to exercise) to make your heart work harder and beat faster while heart tests are performed.
• During exercise stress testing, your blood pressure and EKG readings are monitored while you walk or run on a treadmill or pedal a bicycle. Other heart tests, such as nuclear heart scanning or echocardiography, also can be done at the same time. These would be ordered if your doctor needs more information than the exercise stress test can provide about how well your heart is working.
• If you are unable to exercise, a medicine can be injected through an intravenous line (IV) into your bloodstream to make your heart work harder and beat faster, as if you are exercising on a treadmill or bicycle. Nuclear heart scanning or echocardiography is then usually done.
• During nuclear heart scanning, radioactive tracer is injected into your bloodstream, and a special camera shows the flow of blood through your heart and arteries. Echocardiography uses sound waves to show blood flow through the chambers and valves of your heart and to show the strength of your heart muscle.
• Your doctor also may order two newer tests along with stress testing if more information is needed about how well your heart works. These new tests are magnetic resonance imaging (MRI) and positron emission tomography (PET) scanning of the heart. MRI shows detailed images of the structures and beating of your heart, which may help your doctor better assess if parts of your heart are weak or damaged. PET scanning shows the level of chemical activity in different areas of your heart. This can help your doctor determine if enough blood is flowing to the areas of your heart. A PET scan can show decreased blood flow caused by disease or damaged muscles that may not be detected by other scanning methods.