Using Blood Tests to Diagnose Heart Disease

Blood carries nutrients, oxygen and waste products through the body. Therefore, a small sample of blood can provide a doctor with a wealth of information.

Since chest pain can have a variety of causes, from mild to severe conditions, one initial test to help determine the cause might be a simple blood test.

Blood Explained

Blood contains a variety of cells that are suspended within the light-colored fluid called plasma. Plasma also contains several other dissolved substances, including:

• antibodies
• clotting factors
• electrolytes
• enzymes
• hormones
• nutrients
• vitamins.

There are also three different types of blood cells in plasma:

• platelets
• red blood cells
• white blood cells.

Red blood cells take oxygen to the various tissues of the body, white blood cells serve the body's immune system by fighting foreign organisms and platelets help the blood to clot.

Since blood has all of these substances, it can be used to evaluate the condition of major organs such as the heart.

How Blood Tests are Performed

In an adult, testing blood is easy. A medical technician will use a needle to draw blood from either an artery or vein, depending on what sort of sample is needed. In general, blood tests rarely take longer than five minutes and are fairly painless.

In children or babies, the medical technician may simply use a finger prick to draw a few drops of blood for testing, or he may even draw blood from the heel.

Blood Tests and Cardiovascular Conditions

A simple blood test can help to determine whether a certain person is at higher risk for heart disease by checking for abnormal cholesterol or triglyceride levels.

Blood tests can also establish whether or not a heart attack has occurred and can also help determine the extent of the damage a heart attack has caused by measuring the blood levels of certain cardiac enzymes. For instance, some cardiac enzymes are normally found only in the heart muscle itself, but they can leak into the blood as a result of damage to the heart. In other cases, the heart releases certain enzymes into the blood when it does not receive enough oxygen.

Common Cardiovascular Blood Tests

Certain blood tests are used fairly often to diagnose and manage heart disease, including:

• Arterial Blood Gases Test: In this blood test, the medical technician will draw blood from an artery rather than a vein to determine the blood's oxygen levels.
• BNP Blood Test: The levels of B-type natriuretic peptide (BNP), a type of hormone, tend to rise during heart failure. In this blood test, BNP levels are measured.
• Cardiac Enzyme Test: Measuring the number of heart enzymes, including creatine phosphokinase (CK), can help determine whether a patient's chest pain indicates that a heart attack has occurred. Within four to eight hours of a heart attack, the levels of CK typically rise. They return to normal within 72 hours of a heart attack.
• Electrolyte Panel: This test assesses how well major organ systems, such as the cardiovascular system, are functioning by measuring the levels of potassium, sodium, chloride and carbon dioxide in the blood.
• Lipid Panel: Also called a blood fat profile, this type of test measures fat and fat-like substances in the blood, including cholesterol, triglycerides and low-density lipoproteins. High levels of these substances are often associated with heart disease.

Blood Test Results

Blood test results will be analyzed against a normal range for that specific test. If a patient's results fall either above or below that normal range, it can indicate a health problem. In those cases, a doctor may wish to test the blood a second time in order to confirm the initial results, or he may want to proceed with additional tests to further diagnose the condition or disease.

Resources

iVillage Inc. (n.d.) Blood Tests. Retrieved November 15, 2007, from the iVillage.com Web site: http://yourtotalhealth.ivillage.com/blood-tests.html.

Mayo Clinic Staff. (n.d.) Chest Pain. Retrieved November 15, 2007, from the MayoClinic.com Web site: http://www.mayoclinic.com/health/chest-pain/DS00016/DSECTION=4.