Cardiac Diagnostic Procedures

Laboratory and Function TestBy Mary E. Martin

Laboratory Test

•Cardiac Enzymes- Blood test to determine the levels of enzymes specific to heart muscles in the blood. An increase in the enzymes may indicate heart muscle damage such as myocardial infarction. These enzymes include creatine phosphokinase (CPK), lactate dehydrogenase (LDH), and glutamic oxaloacetic transaminase (GOT). Elevation of CPK is an indication of damage to muscle. It is therefore indicative of injury, rhabdomyolysis, myocardical infarction, myositis and mycarditis. Lowered CK can be an indication of alcoholic liver disease and rheumatoid arthritis.

Laboratory Test

•Cardiac Scan-Patient is given radioactive thallium intravenously and the scanning equipment is used to visualize the heart. It is especially useful in determining myocardial damage. Following imaging, you will undergo a stress test, which requires you to exercise either by walking on a treadmill or pedaling a stationary bicycle for a few minutes. While you exercise, the electrical activity of your heart will be monitored by electrocardiography (ECG) and your blood pressure will be frequently measured. When blood flow to the heart has reached its peak, you will be given the radiotracer through your IV. After you complete the stress test, you may be asked to drink some water. Approximately 20 to 40 minutes later you will be placed on the imaging table a second time so a second series of images can be recorded.

Cardiac Function Test

• Electrocardiogram-The process of recording the electrical activity of the heart. Useful in the diagnosis of abnormal cardiac rhythm and heart muscle damage. An electrocardiogram is a painless, noninvasive way to diagnose many common types of heart problems. Your doctor may use an electrocardiogram to detect:

• Irregularities in your heart rhythm (arrhythmias) • Heart defects • Problems with your heart's valves • Blocked or narrowed arteries in your heart (coronary artery

disease) • A heart attack, in emergency situations • A previous heart attack

• An electrocardiogram monitors your heart rhythm for problems. Electrodes are taped to your chest to record your heart's electrical signals, which cause your heart to beat. The signals are shown as waves on an attached computer monitor or printer.

• Normal EKG

A typical EKG tracing of the cardiac cycle (heartbeat) consist of a P wave, a QRS complex, a T wave, and U wave which is normally visible in 50 to 75% of EKG’s.