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Clinical Cardiac Pacing and Defibrillation

When the heart can no longer control its own rhythms and exhibits a fluttery, irregular pattern, the patient is experiencing fibrillation and may go into cardiac arrest. In such cases, internal or external defibrillators shock the heart back into its normal pace. The American Heart Association notes that timely defibrillation helps save the lives of up to 40 percent of patients who suffer cardiac arrest, compared to the overall cardiac arrest death rate of 95 percent.

  1. Normal Heartbeat

    • Under normal circumstances, the heart controls the rhythm and rate of its beats with its own natural pacemaker. This component tells the organ how often to beat based on signals it receives from the brain. According to Aurora Health Care, illness, drugs, electrocution or other stimuli can cause the heart to fibrillate, an uncontrolled heartbeat pattern that can cause cardiac arrest. Heart stoppage from cardiac arrest quickly leads to brain damage and death.

    Techniques

    • Medical personnel can correct heart rate and rhythm either externally or internally. In emergency situations, an electric defibrillator allows for immediate treatment through the use of electrified paddles placed against the chest. The jolt from the defibrillator alters the electrical signals in the heart, hopefully returning it to its normal rhythm. If the heart’s natural pacemaker has lost its ability to set and maintain a natural rhythm, a cardiac surgeon may install an implantable cardioverter defibrillator, or ICD, to regulate the heartbeat pattern.

    Equipment

    • An ICD as a pager-sized unit consisting of a pulse generator, a triggering circuit and a set of electrodes implanted into the heart muscle. The electrodes respond to heart fibrillation by sending a signal to the circuit, which then routes electricity from an internal battery back through the electrodes to jolt the heart. External defibrillator units include a portable battery pack and electrodes that medical personnel place directly over the heart.

    Training

    • Different cardiac pacing devices call for different types of training. Implantation of an ICD requires a skilled, experienced cardiac surgeon. Emergency medical technicians learn how to use external defibrillators in case of emergencies. According to the Journal of the American Medical Association, the effectiveness of external defibrillation hinges on the quality of training and communication among these personnel.

    Limitations

    • These lifesaving devices do not always work perfectly. Internal defibrillators require occasional replacement of their internal battery to ensure continued reliability. External defibrillators require ongoing maintenance for their functional status, yet the Journal of the American Medical Association states that some medical facilities fail to take these steps consistently. Implantable devices also face reliability issues at times. In 2007, Medtronic, a medical device manufacturer, had to recall defective ICD components that caused unnecessary shocks in patients.

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