Wolff-Parkinson-White Syndrome

Diagnosis

The most common form of life-threatening heart rhythm in patients with WPW syndrome is atrial fibrillation, a condition in which the electrical activity in the heart's upper chambers (atria) becomes chaotic and very fast (300 to 400 impulses per minute). When atrial fibrillation occurs in patients without WPW, the heart's conduction system allows only a fraction of these beats to reach the ventricles.

In some cases of WPW syndrome, as many as 350 of the electrical impulses can reach the heart's lower chambers (ventricles). This interferes with the heart's ability to effectively pump blood, a life-threatening heart rhythm abnormality.

A comprehensive diagnosis at Mayo Clinic helps to determine how WPW syndrome affects the heart.

To diagnose Wolff-Parkinson-White syndrome, the patient may be asked about or tested for conditions that may trigger the abnormally fast heartbeat, such as heart disease or a thyroid problem. The patient may have two heart monitoring tests: active and passive.

Active Tests

These tests involve trying to actively induce an irregular heart beat while the patient is monitored closely. They include:

Electrophysiology (EP) testing and mapping
Mayo Clinic is an international leader in catheter ablation and implantable devices and uses the most advanced technology to treat arrhythmias. The electrophysiology lab has over 25 years of experience in treating patients who have various heart arrhythmias.

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

In the controlled laboratory setting, the electrophysiologist (a cardiologist who specializes in heart rhythms) 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 then stop a Wolff-Parkinson-White syndrome may also be used to test the effectiveness of various treatment methods. For example, if catheter radiofrequency ablation — a catheter-based treatment option for many arrhythmias — is determined by the doctor to be appropriate, the procedure can be performed during EP testing. Read more about atrial fibrillation ablation.

Stress test
Wolff-Parkinson-White syndrome may be triggered or worsen when the patient exercises. During a stress test, the patient may exercise on a treadmill or stationary bicycle, with an electrocardiogram (ECG) monitoring heart activity. The test may involve a drug to stimulate the heart similar to exercise. This may help patients who have difficulty exercising. The stress test can also be used to detect coronary artery disease.

Passive Tests

These tests involve monitoring the heart during regular activity. They include:

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

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 during the daily routine.

Echocardiogram (Doppler echocardiogram)
This test uses sound waves to produce detailed images of the patient's heart. Through a handheld device (transducer) 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.

The comprehensive diagnosis is critical in determining the best treatment for the patient.