Bradycardia

Diagnosis

A comprehensive diagnosis at Mayo Clinic helps determine what is causing the bradycardia and the most appropriate treatment for each patient. At Mayo Clinic, electrophysiologists (cardiologists with specialized training in the diagnosis and treatment of heart rhythm disorders) work with a team of medical specialists to accurately diagnose and effectively treat each patient with bradycardia and other heart rhythm disorders.

To diagnose bradycardia, the physician may ask the patient about the existence of circumstances or conditions that trigger the slower heart rate, such as medications or heart disease, or may test for certain conditions. Several tests may be conducted to better understand the cause of the bradycardia.

Electrophysiology (EP) testing and mapping
Mayo Clinic is a national leader in electrophysiology, the medical specialty of heart rhythms. At each of its locations, Mayo Clinic has experienced electrophysiologists. Electrophysiology testing is usually only conducted if other tests have not been effective in diagnosing the bradycardia.

Catheters (thin, flexible tubes) with electrodes at the tips are threaded through the patient's blood vessels to various locations within the heart. Once in place, the electrodes can precisely map the spread of electrical impulses through the heart.

During the test, the electrophysiologist may use the electrodes to stimulate the heart to beat at rates that may trigger, or halt, an irregular heartbeat. The physician can observe the location of the arrhythmia and the mechanics of the heart that may be causing the irregular heartbeat.

The ability to trigger and stop a bradycardia may also be used to test the effectiveness of various treatment methods. For example, if catheter radiofrequency ablation (a minimally-invasive procedure that uses catheters to reach the heart and destroy abnormal heart tissue) is determined by the doctor to be appropriate treatment, the procedure can be performed during EP testing. Read more about catheter radiofrequency ablation.

Electrocardiogram (ECG)
Electrodes (sensor patches with wires attached) are placed on the patient's skin to measure electrical impulses given off by the heart. The ECG measures the timing and duration of each electrical phase in the heartbeat.

Blood tests
These may help identify whether medication, a thyroid problem, or other medical problems are causing the bradycardia.

Echocardiogram (Doppler echocardiogram)
Sound waves produce detailed images of the patient's heart. Through a handheld device (transducer) placed on the patient's chest, sound waves bounce off the heart and are reflected to produce video images of the heart's size, structure and motion. The echocardiogram can help measure the heart's blood volume and the speed and direction of blood flow through the heart.

Stress test
Bradycardia may be triggered or worsen when the patient exercises. During a stress test, the person exercises on a treadmill or stationary bicycle with close monitoring by an electrocardiograph (ECG) of heart activity. If patients have difficulty exercising, a drug may be given to stimulate the heart into mimicking its activity during exercise. The stress test can also be used to detect coronary artery disease.

Some tests involve monitoring the heart during activity.

Holter monitor
A Holter monitor is a portable ECG device that the patient wears for a day or more to record the heart's electrical activity.

Event monitor
For irregular heartbeats that occur sporadically, this portable ECG device is kept at home so the patient can attach it and activate the ECG recording when experiencing symptoms of an arrhythmia. The device is small, about the size of a portable compact disc player, and can be clipped on to clothing. Patients can apply the electrodes (sticky pads with wires) to his or her chest. When the patient feels symptoms, a push of a button begins the ECG recording. For select patients, an implanted recorder may be used.