Atrial Flutter

Atrial flutter occurs when a single electrical signal circulates rapidly in the atrium, causing a very fast but steady heartbeat. Not every beat is conducted through the AV node, impairing blood flow from the ventricles.

Atrial flutter often occurs in people with heart disease, or after a heart attack or chest trauma. It creates an unpleasant fluttering sensation in the chest. Although it is not life-threatening, it should be treated to avoid its progression to a more serious type of arrhythmia, such as atrial fibrillation.

Catheter ablation is the electrophysiologist treatment of choice for atrial flutter and has a very high success rate in relieving patients of the symptoms.

Ventricular Tachycardia

Ventricular tachycardia is a fast heart rate -- anything over the normal 100 beats per minute -- which starts in the lower chambers of the heart, the ventricles. It causes the ventricles to contract before they have had a chance to completely fill with blood, impairing blood flow to the body.

Ventricular tachycardia occurs in people with underlying heart abnormalities. In those who have had a heart attack, for example, the scar from the heart attack causes the electrical abnormalities that create the tachycardia.

This is a serious disorder and requires prompt treatment. It poses a serious danger in that it may evolve into the more serious ventricular fibrillation. In this life-threatening condition, the ventricles quiver, pumping very little blood out of the heart. Ventricular fibrillation is the primary cause of sudden cardiac death. If normal rhythm is not restored within 3-5 minutes, the heart and brain will be damaged, and the patient will die.

Severe ventricular tachycardia and ventricular fibrillation can be converted into normal rhythm with a controlled electrical shock from a defibrillator.

Regular treatment of ventricular tachycardia includes medications to slow the heart rate. High-risk patients are treated with an implantable cardioverter-defibrillator (ICD). This device, which is inserted under the skin of the chest like a pacemaker, senses irregular rhythms and automatically shocks the heart back into normal rhythm.

Catheter ablation is being increasingly used to interrupt the faulty pathways that cause ventricular tachycardia. Until recently, doctors could not pinpoint these tachycardias well enough to ablate them. With new technology, however, they can accurately map most ventricular tachycardias, enabling elimination of the abnormal signals that cause them.

Supraventricular Tachycardia (SVT)

Supraventricular tachycardia (SVT) is a general name for arrhythmias that start above the ventricles. It is sometimes called paroxysmal supraventricular tachycardia (PSVT) because it occurs intermittently, or from time to time.
SVTs usually begin and end suddenly, and can last anywhere from seconds to hours. They may cause the heart to beat 160-200 times a minute.
SVTs are generally not life-threatening, unless the patient has another heart problem. Symptoms can vary in severity, and the more severe forms may require treatment with medications or catheter ablation.

AV Nodal Re-entrant Tachycardia (AVNRT)

This type of abnormal rhythm arises from malfunctioning of the AV node. In most people, the AV node conducts impulses along a single pathway. In AVNRT, a second conducting pathway arises, confusing the electrical signals traveling from atria to ventricles. As a result, both the atria and ventricles beat at the same time instead of in sequence. This creates a fast heart rate -- 120-250 beats per minute. Although the heartbeat is typically regular, rather than erratic, the heart is not pumping efficiently. Most AVNRT patients do not have underlying heart disease.

Wolff-Parkinson-White (WPW) Syndrome

This syndrome occurs in people who have a second, accessory pathway that conducts electrical signals between the atria and ventricles. WPW is usually hereditary or associated with congenital (present at birth) or acquired heart defects. In WPW, electrical signals bypass the AV node and use the extra pathway. They reach the ventricles too soon and bounce back to the atria. The signals ricochet around the inside of the heart, causing very fast heartbeats.

Although most people with WPW do not have symptoms, in some it can pose a serious risk for sudden death.

Catheter ablation should be performed on symptomatic patients because of the risk of sudden death. Catheter ablation cures the disorder by destroying the extra pathway in 85-95% of cases, depending on the location of the pathway.