The first step in diagnosing heart block is for a physician to obtain a patient’s complete medical history and to give the patient a complete physical examination. Blood tests may also be ordered to rule out electrolyte imbalances, or detect cardiac enzymes associated with a past heart attack or abnormally high levels of prescribed medications in the bloodstream.

Next, the physician will order a common, painless test called an electrocardiogram (EKG). This test measures the heart’s electrical activity at rest and under stress (stress test). The information obtained from the test will help the physician determine if the electrical impulses are being delayed or blocked as they travel through the heart’s normal conduction system. By examining the results of an EKG, a physician will likely be able to identify the distinctive heart rhythms characteristic of a heart block and to prescribe appropriate treatments, if necessary.

If heart block occurs only infrequently, it might not be picked up by tests during a scheduled office visit. Therefore, a portable EKG (ambulatory electrocardiogram) may be ordered. A portable EKG measures heart activity while the patient is “on the move” instead of in a physician’s office. The heart’s electrical activity is recorded on a portable tape inside the machine. There are two categories of AECG (ambulatory electrocardiography) recorders:

Depending on the results of the EKG and/or portable EKG, a physician may then order a test called an electrophysiology study. This test requires the insertion of several thin tubes (catheters) into veins (usually in the groin) from where they are guided to the heart. This test enables physicians to perform specific measurements of the heart’s electrical activity and pathways.

Other tests used to diagnose heart block include:

• Echcardiogram. Uses sound waves to create pictures of the heart and its blood vessels. A moving image of the patient’s beating heart is played on a video screen, where a physician can study the heart’s thickness, size and function. This test may be ordered when a problem is suspected in the heart muscle or one the heart’s valves.
  
  
• Tilt table test. Conducted on a pivoting table, this test involves securing the patient on his or her back, and then tilting the table upright (head up and feet down). This test may be used to determine the cause of fainting spells (syncope). This is not a direct test for heart block. It is used to rule out conditions with similar symptoms.