Types of Rhythm Disorders (Arrhythmias)

Atrial fibrillation (A fib) occurs when multiple sites in the atria (upper chambers of the heart) fire signals in an uncoordinated fashion. This results in very rapid and ineffective beating in the atria. There is no coordination between the upper and lower chambers of the heart. The heart pumps less efficiently. The rhythm is irregular. People with this condition may or may not feel the irregular rhythm. Some may experience palpitations, shortness of breath, dizziness, heart failure or edema. The heart may go in and out of rhythm by itself, or it may stay out of rhythm. A cardioversion may restore normal rhythm.

Atrial flutter (A fl) is a more organized rhythm that starts in the atria (upper chambers of the heart), but it is still a disorganized rhythm with the lower chambers of the heart. It can lead to a fast, fairly regular rhythm from the lower chambers. It can lead to palpitations, shortness of breath, dizziness and/or heart failure. This rhythm can be stopped with a cardioversion or cured with an ablation.

Supraventricular tachycardia (SVT) is a series of rapid heartbeats that begin in the atrium (upper chambers of the heart). An extra pathway exists in the atria, in the AV node or between the atria and the ventricles. AV nodal reentrant tachycardia (AVNRT) is the most common form of SVT. With this rhythm, the extra pathway exists in or near the AV node. Once this pathway is activated, the heart beats in a fast regular rhythm. These rhythms are very successfully cured with an ablation procedure.

Syncope results when a person's blood pressure drops too low and the brain does not receive enough blood. It may be a sign of a serious problem. Sometimes, despite an extensive medical work-up, the cause of the syncope may not be discovered. Sometimes, a change in lifestyle or diet may be necessary. Medications may be needed or a pacemaker or ICD (implantable cardiac defibrillator) may need to be implanted depending on the cause of the syncope.

Ventricular fibrillation (VF) results when multiple sites in the ventricles fire impulses very rapidly and erratically. This causes the ventricles to quiver and cease pumping blood effectively. When the heart is in VF, little blood is pumped through the body, causing cardiac arrest. Emergency treatment must be given to restore normal function to the heart and restore its pumping action or death will occur.

Ventricular tachycardia (VT)
Hearts damaged by cardiac disease, such as a myocardial infarction will have abnormal electrical pathways in the ventricles. If an electrical signal enters one of these pathways, it may start traveling in a circular pattern around the ventricles. The ventricles then contract with each cycle, which results in a very rapid heartbeat. VT does not allow sufficient time for the heart to fill with blood. This results in a decreased pumping ability of the heart and leads to a decrease in blood pressure and a decrease in blood supply to the heart and brain. This may result in dizziness, chest pain, or syncope (fainting spell). VT may not stop by itself, progressing into ventricular fibrillation, cardiac arrest and eventual death, if not treated.

Wolff-Parkinson-White Syndrome (WPW) is caused when there is an abnormal connection (an accessory pathway) of tissue between the atria and the ventricles. It allows electrical signals to travel from the atria to the ventricles without going through the AV node. When this pathway or connection is activated, the heart beats very rapidly.