Diagnosing Heart Disease
February 1, 2013
Various tests are used to diagnose heart disease. Your doctor will start by taking your personal and family medical history, recording current and past symptoms, and doing laboratory tests and an electrocardiogram. Based on the results of the assessment and tests, your doctor may order further tests.
Some of these tests are non-invasive, which means no instruments are inserted into the body. Other tests are invasive and require inserting instruments into the body.
Laboratory tests include blood tests to determine your risk of heart disease as well as to evaluate other systems of your body that can affect your cardiovascular health.
Blood is drawn from a vein in your arm. Some tests require fasting for 12 hours, but most do not have any dietary restriction.
Blood Tests for Heart Disease
- Total cholesterol
- LDL (low-density lipoprotein), the so-called "bad" cholesterol
- HDL (high-density lipoprotein), the so-called "good" cholesterol
3. C-reactive protein (CRP)
Your liver produces C-reactive protein (CRP) as part of your body's response to injury or infection. Inflammation plays a central role in the process of atherosclerosis, in which fatty deposits clog your arteries.
CRP test results combined with other blood test results and risk factors for heart disease help create an overall picture of your heart health.
Your body uses homocysteine to make protein and to build and maintain tissue. However, too much homocysteine may increase your risk of heart disease and stroke. Homocysteine is usually ordered for people who have a high risk for developing heart disease or have a known history of heart disease. It is also used for people with a family history of heart disease but no other known risk factors.
Blood Tests for Other Body Systems
1. Complete blood count (CBC)
CBC is a series of tests that measures your red blood cells, white blood cells and platelets.
2. Sodium and potassium levels
Sodium and potassium levels are measured to detect a problem with electrolytes in the body fluids.
5. ALT and AST
ALT and AST is performed to detect liver inflammation or damage.
TSH is measured to check thyroid function.
An electrocardiogram (EKG or ECG) is a graphic measure of the electrical activity in your heart. There are specific patterns on the EKG that your doctor looks for to determine whether there are abnormalities such as atrial fibrillation (an abnormal rhythm), or new or old heart attack.
During the test, you will lie on an exam table while an electrocardiograph machine records the information. You will be attached to the electrocardiograph by stickers on your chest that are connected to wires leading to the machine. The test takes less than five minutes.
An echocardiogram ("echo") is an ultrasound of the heart. A small probe like a microphone, called a transducer, is placed on the chest in various places. The ultrasound waves sent by the transducer bounce off the various parts of the heart. A computer in the machine determines the time it takes for the sound wave to return to the transducer and generates a picture with the data.
During the test, you will lie on your back or left side on a stretcher for about 45 minutes while the pictures are being recorded. The echocardiographer will review the pictures before sending you home to be sure all the necessary information has been obtained.
Stress EKG or Echocardiogram
Stress tests are performed to see how the heart performs under physical stress. The heart can be stressed with exercise on a treadmill or in a few instances, a bicycle. If a person cannot exercise on a treadmill or bicycle, medications can be used to cause the heart rate to increase, simulating normal reactions of the heart to exercise.
During the stress test, you will wear EKG leads and wires while exercising so that the electrical signals of your heart can be recorded at the same time. Your blood pressure is monitored throughout the test. The stress test can be performed together with the echocardiogram, described above.
Nuclear Stress Test
Nuclear stress tests have two components to them: a treadmill (or chemical) stress test and scanning of the heart after injection of a radionuclide material. This material has been used safely for many years to determine the amount of blood the heart muscle is receiving during rest and stress. The scanning is done with a nuclear camera.
Carotid ultrasound is done to evaluate your risk of stroke. The sonographer presses the transducer gently against the sides of your neck, which sends images of your arteries to a computer screen for the technician to see. The technician monitors your blood flow through the carotid arteries on both sides of your neck to check for stenosis.
During the exam, you lie on your back on an examination table and a small amount of warm gel is applied to your skin. The test usually takes about 15 to 30 minutes.
Your doctor may also want you to have an abdominal ultrasound to screen for potential abdominal aortic aneurysm. The sonographer presses the transducer against the skin over your abdomen, moving from one area to another. The transducer sends images to a computer screen that the technician monitors. The technician monitors blood flow through your abdominal aorta to check for an aneurysm.
During the exam, you lie on your back on an examination table and a small amount of warm gel is applied to your abdomen. The test usually takes between 20 minutes to an hour.
A Holter monitor is a small, portable machine that you wear for 24 to 48 hours. It enables continuous recording of your EKG as you go about your daily activities. You will be asked to keep a diary log of your activities and symptoms. This monitor can detect arrhythmias that might not show up on a resting EKG that only records for a few seconds.
An event recorder (loop recorder) is a small, portable transtelephonic monitor that may be worn for several weeks. This type of recorder is good for patients whose symptoms are infrequent.
The monitor 'loops' a two- to five-minute recording into its memory which is continually overwritten. When you experience symptoms you press a 'record' button on the monitor, which stores a correlating strip of EKG. The recordings are telephoned through to a 24-hour monitoring station and faxed directly to your doctor.
Cardiac Catheterization and Coronary Angiography
Cardiac catheterization is a common procedure that can help diagnose heart disease. In some cases, catheterization is also used to treat heart disease by opening blocked arteries with balloon angioplasty and stent placement.
Cardiac catheterization can show:
- If the blood vessels in your heart have narrowed.
- If your heart is pumping normally and blood is flowing correctly.
- If the valves in your heart are functioning normally.
- If you were born with any heart abnormalities.
- If the pressures in the heart and lung are normal. If not, catheterization can help assess the problem.
During catheterization, the cardiologist inserts a long, flexible tube called a catheter into a blood vessel, either through the wrist artery or the groin artery, and gently guides it towards your heart under X-ray guidance. Once the catheter is in place, X-rays and other tests are done to help your doctor evaluate whether your coronary arteries are blocked and how well your heart is working.
At times, it might also be necessary to insert a small catheter into a vein to allow measurement of specific pressures in the heart and lung. This procedure can be done either through a neck vein, arm vein or groin vein.
An electrophysiology study (EP) is a recording of the electrical activity of the heart. This test helps your doctor determine the cause of your rhythm disturbance (arrhythmia) and the best treatment. During the test, the doctor may safely reproduce the arrhythmia, and then give certain medications to see which one controls it best.
An EP study is performed in the Electrophysiology Laboratory, where you will lie on an X-ray table. As with a cardiac catheterization, the doctor inserts a long, flexible tube — an electrode catheter — into a blood vessel, usually in the groin.
There are stages in an EP study:
1. Recording the heart's electrical signals to assess electrical function.
2. Pacing the heart to bring on certain abnormal rhythms for observation under controlled conditions.
3. In some cases, an ablation procedure is performed at the same time to destroy abnormal tissue which may be causing the arrhythmia.
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