The electrical signal continues in a downward fashion through the "atrio-ventricular" or AV node, where the signal is slowed slightly by special tissue. The AV node is the "doorway" or relay station to the bundle of His (pronounced Hiss) and the bundle branches in the lower chambers of the heart.

After passing through the left and right bundle branches, the impulse arrives at the Purkinje fibers, where it is transmitted to the muscle cells of the left and right ventricles. Because of the specialized way in which the impulse is transmitted, the ventricles contract almost simultaneously.

With normal conduction, the cardiac contractions are very organized and timed so that the top chambers (the atria) contract before the lower chambers and the heart rate is maintained between 60 and 100 beats per minute.

Legend:

1. The SA Node.
2. The AV Node.
3. The Bundle of His.
4. The Bundle Branches.
5. The Purkinje fibers.

Ventricular tachycardia may be controlled by medication in some cases. If medications are not effective, the physician may elect to control the rhythm by electrical methods. The most common electrical therapy for VT is implantation of a device known as an Implantable Cardioverter Defibrillator or ICD. The ICD applies an electric shock to the heart muscle to interrupt or disrupt the fast rhythm. The electric shock may be in the form of specially timed pacemaker pulses (unfelt by the patient) or by high voltage shock. The high voltage shock, if required, is usually felt by the patient.

x

ICD SUPPORT GROUPS