Defibrillators and pacemakers are devices that can be inserted into the heart, or used temporarily over the chest to manipulate the electrical activity of the heart. The heart uses electricity to coordinate contractions in order to efficiently pump blood through the body. Defibrillator and pacemakers are similar in that they use electrical currents to assist the heart, but they have important differences.
Electrical Discharge
Defibrillators discharge a large amount of electricity at once, according to "Hurst's the Heart" by Dr. Valentin Fuster. More electricity is required for defibrillators placed over the chest in order for the charge to reach the heart through the tissues of the chest wall. In contrast, a pacemaker uses weaker amounts of electricity, but delivers a charge followed by another in a continuous fashion.
Conditions Treated
A defibrillator is typically used to treat potentially lethal disturbances of the heart. The device is called a "de-fibrillator" because it stops fibrillation of the heart. Fibrillation is when the muscle fibers of the heart quiver and contract rapidly in an unsynchronized fashion. When this occurs, blood is not pumped out to the body; this can cause unconsciousness within seconds and be lethal. The defibrillator discharges electricity to reset the heart and break the fibrillation.
A pacemaker is used to set the rate of contraction of the heart. The heart has a natural pacemaker that causes it to contract over and over. If the natural pacemaker malfunctions, an artificial pacemaker may be needed. In bradycardia, the heart beats too slowly. A pacemaker can repeatedly discharge electricity at a faster rate to speed the heart up.
Settings
Since a defibrillator discharges a large amount electricity at once, settings modulate how the charge is delivered. For example, the charge may be always delivered at the highest setting, or increasingly larger charges can be given if the previous charge fails to break the rhythm.
A pacemaker has multiple settings, such as how quickly to pace the heart, where in the heart to monitor for rhythm problems and where to pace the heart.
References
- "Hurst's the Heart"; Valentin Fuster, Robert O'Rourke, Richard Walsh, and Philip Poole-Wilson; 12th Ed 2007
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci MD et al; 17th Ed 2008
