Heart block might be diagnosed as part of a routine doctor's visit or during an emergency situation. (Third-degree heart block often is an emergency.)
                
Your doctor will diagnose heart block based on your family and medical histories, a physical exam, and test results.
                
Specialists Involved
                
Your primary care doctor might be involved in diagnosing heart block. However, if you have the condition, you might need to see a heart specialist. Heart specialists include:
                
Cardiologists (doctors who diagnose and treat adults who have heart problems)
                
Pediatric cardiologists (doctors who diagnose and treat babies and children who have heart problems)
                
Electrophysiologists (cardiologists or pediatric cardiologists who specialize in the heart's electrical system)
                
Family and Medical Histories
                
Your doctor may ask whether:
                
You have any signs or symptoms of heart block
                
You have any health problems, such as heart disease
                
Any of your family members have been diagnosed with heart block or other health problems
                
You're taking any medicines, including herbal products and prescription and over-the-counter medicines
                
You smoke or use alcohol or drugs
                
Your doctor also may ask about other health habits, such as how physically active you are.
                
Physical Exam
                
During the physical exam, your doctor will listen to your heart. He or she will listen carefully for abnormal rhythms or heart murmurs (extra or unusual sounds heard during heartbeats).
                
Your doctor also may:
                
Check your pulse to find out how fast your heart is beating
                
Check for swelling in your legs or feet, which could be a sign of an enlarged heart or heart failure
                
Look for signs of other diseases that could be causing heart rate or rhythm problems (such as coronary heart disease)
                
Diagnostic Tests and Procedures
                
EKG (Electrocardiogram)
                
Doctors usually use an EKG (electrocardiogram) to help diagnose heart block. This simple test detects and records the heart's electrical activity.
                
An EKG shows how fast the heart is beating and its rhythm (steady or irregular). The test also records the strength and timing of electrical signals as they pass through the heart.
                
The data are recorded on a graph. Different types of heart block have different patterns on the graph. (For more information, go to "Types of Heart Block.")
                
A standard EKG only records the heart's activity for a few seconds. To diagnose heart rhythm problems that come and go, your doctor may have you wear a portable EKG monitor.
                
The most common types of portable EKGs are Holter and event monitors. Your doctor may have you use one of these monitors to diagnose first- or second-degree heart block.
                
Holter and Event Monitors
                
A Holter monitor records the heart's electrical signals for a full 24- or 48-hour period. You wear one while you do your normal daily activities. This allows the monitor to record your heart for a longer time than a standard EKG.
                
An event monitor is similar to a Holter monitor. You wear an event monitor while doing your normal activities. However, an event monitor only records your heart's electrical activity at certain times while you're wearing it.
                
You may wear an event monitor for 1 to 2 months, or as long as it takes to get a recording of your heart during symptoms.
                
Electrophysiology Study
                
For some cases of heart block, doctors may do electrophysiology studies (EPS). During this test, a thin, flexible wire is passed through a vein in your groin (upper thigh) or arm to your heart. The wire records your heart's electrical signals.
                
Other Tests
                
To diagnose heart block, your doctor may recommend tests to rule out other types of arrhythmias (irregular heartbeats). For more information, go to "How Are Arrhythmias Diagnosed?"