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Defibrillation

Defibrillation

Definition

Defibrillation is a process in which an electrical device called a defibrillator sends an electric shock to the heart to stop an arrhythmia resulting in the return of a productive heart rhythm.


Purpose

Defibrillation is performed to correct life-threatening arrhythmias of the heart including ventricular fibrillation and cardiac arrest. In cardiac emergencies it should be performed immediately after identifying that the patient is experiencing an arrhythmia, indicated by lack of pulse and unresponsiveness. If an electrocardiogram is available, the arrhythmia can be displayed visually for additional confirmation. For medical treatment by a physician, in non-life threatening situations, atrial defibrillation can be used to treat atrial fibrillation or flutter.


Precautions

Defibrillation should not be performed on a patient who has a pulse or is alert, as this could cause a lethal heart rhythm disturbance or cardiac arrest. The paddles used in the procedure should not be placed on a woman's breasts or over an internal pacemaker.

Cardiac arrhythmias that prevent the heart from pumping blood to the body can cause irreversible damage to the major organs including the brain and heart. These arrhythmias include ventricular tachycardia, fibrillation, and cardiac arrest. About 10% of the ability to restart the heart is lost with every minute that the heart fibrillates. Death can occur in minutes unless a productive heart rhythm, able to generate a pulse, is restored through defibrillation. Because immediate defibrillation is crucial to the patient's survival, the American Heart Association has called for the integration of defibrillation into an effective emergency cardiac care system. The system should include early access, early cardiopulmonary resuscitation , early defibrillation, and early advanced cardiac care.

Defibrillators deliver a brief electric shock to the heart, which enables the heart's natural pacemaker to regain control and establish a productive heart rhythm. The defibrillator is an electronic device that includes defibrillator paddles and electrocardiogram monitoring.

During external defibrillation, the paddles are placed on the patient's chest with a conducting gel ensuring good contact with the skin. When the heart can be visualized directly, during thoracic surgery , sterile internal paddles are applied directly to the heart. Direct contact with the patient is discontinued by all caregivers. If additional defibrillation is required the paddles should be repositioned exactly to increase the likelihood of further shocks being effective in stopping the arrhythmia. The patient's pulse and/or electrocardiogram are continually monitored when defibrillation is not in progress. Medications to treat possible causes of the abnormal heart rhythm may be administered. Defibrillation continues until the patient's condition stabilizes or the procedure is ordered to be discontinued.

Early defibrillators, about the size and weight of a car battery, were used primarily in ambulances and hospitals. The American Heart Association now advocates public access defibrillation; this calls for placing automated external defibrillators (AEDS) in police vehicles, airplanes, and at public events, etc. The AEDS are smaller, lighter, less expensive, and easier to use than the early defibrillators. They are computerized to provide simple, verbal instructions to the operator and to make it impossible to deliver a shock to a patient whose heart is not fibrillating. The placement of AEDs is likely to expand to many public locations.


Preparation

Once a patient is found in cardiac distress, without a pulse and non-responsive, and help is summoned, cardiopulmonary resuscitation (CPR) is begun and continued until the caregivers arrive and are able to provide defibrillation. Electrocardiogram leads are attached to the patient chest. Gel or paste is applied to the defibrillator paddles, or two gel pads are placed on the patient's chest. The caregivers verify lack of a pulse while visualizing the electrocardiogram, assure contact with the patient is discontinued, and deliver the electrical charge.

Atrial defibrillation is a treatment option that will be ordered for treatment of atrial fibrillation or flutter. The electrocardiogram will be monitored throughout the procedure. The paddles are placed on the patients chest with conducting gel to ensure good contact between the paddles and skin. If the heart can be visualized directly during thoracic surgery, the paddles will be applied directly to the heart. The defibrillator is programmed to recognize distinct components of the electrocardiogram and will only fire the electrical shock at the correct time. Again, all direct contact with the patient is discontinued prior to defibrillation.


Aftercare

After defibrillation, the patient's cardiac status, breathing, and vital signs are monitored with a cardiac monitor . Additional tests to measure cardiac damage will be performed, which can include a 12 lead electrocardiogram, a chest x-ray, and cardiac catheterization . Treatment options will be determined from the outcome of these procedures. The patient's skin is cleansed to remove gel and, if necessary, electrical burns are treated.

Risks

Skin burns from the defibrillator paddles are the most common complication of defibrillation. Other risks include injury to the heart muscle, abnormal heart rhythms, and blood clots.


Normal results

Defibrillation performed to treat life-threatening ventricular arrhythmias is most likely to be effective within the first five minutes, preventing brain injury and death by returning the heart to a productive rhythm able to produce a pulse. Patients will be transferred to a hospital critical care unit for additional monitoring, diagnosis, and treatment of the arrhythmia. Intubation may be required for respiratory distress. Medications to improve cardiac function and prevent additional arrhythmias, are frequently administered. Some cardiac function may be lost due to the actual defibrillation, but is also associated with the underlying disease.

Atrial defibrillation is successful at restoring cardiac output, alleviating shortness of breath, and decreasing the occurrence of clot formation in the atria.


Resources

books

giuliani, e. r., et al., eds. "arrhythmias." in mayo clinic practice of cardiology. 3rd ed. st. louis: mosby, 1996.


periodicals

bur, andreas, et al. "effects of bystander first aid, defibrillation and advanced life support on neurological outcome and hospital costs in patients after ventricular fibrillation cardiac arrest." intensive care medicine 27 (2001): 14741480.

herlitz, j., et al. "characteristics and outcome among patients suffering in-hospital cardiac arrest in monitored and non-monitored areas." resuscitation 48 (2001): 125135.

matarese, leonard. "police and aeds: a chance to save thousands of lives each year." public management 79 (june 1997): 4.

"medical breakthroughs that could save your life." body bulletin (february 1998): 1.

"upping the odds of survival." hospitals and health networks 71 (june 5, 1997): 13.

organizations

american heart association. 7320 greenville ave. dallas, tx 75231. (214) 373-6300. <http://www.americanheart.org>

other

"aarc clinical practice guideline: defibrillation during resuscitation." respiratory care 40 (1995): 744748. [cited may 2003]. <http://www.hsc.missouri.edu/~shrp/rtwww/rcweb/aarc/ddrcpg.html>

"defibrillation." american heart association. [cited may 2003]. <http://www.americanheart.org>


Lori De Milto Allison J. Spiwak, MSBME

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"Defibrillation." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Encyclopedia.com. 19 Aug. 2017 <http://www.encyclopedia.com>.

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"Defibrillation." Gale Encyclopedia of Surgery: A Guide for Patients and Caregivers. . Retrieved August 19, 2017 from Encyclopedia.com: http://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/defibrillation-0

Defibrillation

Defibrillation

Definition

Defibrillation is a process in which an electronic device sends an electric shock to the heart to stop an extremely rapid, irregular heartbeat, and restore the normal heart rhythm.

Purpose

Defibrillation is performed to correct life-threatening fibrillations of the heart, which could result in cardiac arrest. It should be performed immediately after identifying that the patient is experiencing a cardiac emergency, has no pulse, and is unresponsive.

Precautions

Defibrillation should not be performed on a patient who has a pulse or is alert, as this could cause a lethal heart rhythm disturbance or cardiac arrest. The paddles used in the procedure should not be placed on a woman's breasts or over a pacemaker.

Description

Fibrillations cause the heart to stop pumping blood, leading to brain damage and/or cardiac arrest. About 10% of the ability to restart the heart is lost with every minute that the heart stays in fibrillation. Death can occur in minutes unless the normal heart rhythm is restored through defibrillation. Because immediate defibrillation is crucial to the patient's survival, the American Heart Association has called for the integration of defibrillation into an effective emergency cardiac care system. The system should include early access, early cardiopulmonary resuscitation, early defibrillation, and early advanced cardiac care.

Defibrillators deliver a brief electric shock to the heart, which enables the heart's natural pacemaker to regain control and establish a normal heart rhythm. The defibrillator is an electronic device with electrocardiogram leads and paddles. During defibrillation, the paddles are placed on the patient's chest, caregivers stand back, and the electric shock is delivered. The patient's pulse and heart rhythm are continually monitored. Medications to treat possible causes of the abnormal heart rhythm may be administered. Defibrillation continues until the patient's condition stabilizes or the procedure is ordered to be discontinued.

Early defibrillators, about the size and weight of a car battery, were used primarily in ambulances and hospitals. The American Heart Association now advocates public access defibrillation; this calls for placing automated external defibrillators (AEDS) in police vehicles, airplanes, and at public events, etc. The AEDS are smaller, lighter, less expensive, and easier to use than the early defibrillators. They are computerized to provide simple, verbal instructions to the operator and to make it impossible to deliver a shock to a patient whose heart is not fibrillating. The placement of AEDs is likely to expand to many public locations.

Preparation

After help is called for, cardiopulmonary resuscitation (CPR) is begun and continued until the caregivers arrive and set up the defibrillator. Electrocardiogram leads are attached to the patient's chest. Gel or paste is applied to the defibrillator paddles, or two gel pads are placed on the patient's chest. The caregivers verify lack of a pulse, and select a charge.

Aftercare

After defibrillation, the patient's cardiac status, breathing, and vital signs are monitored until he or she is stable. Typically, this monitoring takes place after the patient has been removed to an intensive care or cardiac care unit in a hospital. An electrocardiogram and chest x ray are taken. The patient's skin is cleansed to remove gel or paste, and, if necessary, ointment is applied to burns. An intravenous line provides additional medication, as needed.

Risks

Skin burns from the defibrillator paddles are the most common complication of defibrillation. Other risks include injury to the heart muscle, abnormal heart rhythms, and blood clots.

Resources

ORGANIZATIONS

American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org.

KEY TERMS

Cardiac arrest A condition in which the heart stops functioning. Fibrillation can lead to cardiac arrest if not corrected quickly.

Fibrillation Very rapid contractions or twitching of small muscle fibers in the heart.

Pacemaker A surgically implanted electronic device that sends out electrical impulses to regulate a slow or erratic heartbeat.

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defibrillator

defibrillator This is a device used in the treatment of life-threatening disturbances of the rhythm of the heart beat which may occur as the result of a heart attack or a variety of serious injuries or illnesses. Its effect is to ‘reset’ the electrical activity of the heart in the hope that the natural pacemaker cells can then regain control of the rhythm. Defibrillation using direct current, in the form of an unsynchronized countershock, is usually the only way to halt ventricular fibrillation. The countershock from the defibrillator produces a sustained simultaneous excitation (and hence contraction) of all cardiac muscle fibres, which can terminate ventricular fibrillation and other abnormal rhythms. The countershock is administered by pressing a button on each of two defibrillator ‘paddles’ placed on the chest wall. Firm pressure is applied to these paddles to ensure good electrical contact with the skin; this also forces air out of the lungs to bring the chest wall in closer contact with the heart. While the shock is discharged, the patient often ‘jumps’ because motor nerves and skeletal muscles are simultaneously, unavoidably stimulated.

David J. Miller, and Niall MacFarlane


See also cardiac arrest; electrocardiogram; heart; heart attack.

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defibrillator

defibrillator, device that delivers an electrical shock to the heart in order to stop certain forms of rapid heart rhythm disturbances (arrhythmias). The shock changes a fibrillation to an organized rhythm or changes a very rapid and ineffective cardiac rhythm to a slower, more effective one. In a typical hospital defibrillator, voltage stored by the defibrillator pushes electrical current through the chest to deliver a muscle-contracting jolt to the heart; the current is transmitted by means of electrodes or paddles placed on the chest. Automated external defibrillators are now available for use by persons with minimal medical training in emergencies when medical professionals are unavailable, and miniaturization has led to the development of the implanted internal defibrillator (also called an internal cardioverter). In the latter a microcomputer uses an electrode to monitor the heartbeat. Upon detecting a minor arrhythmia, it activates a built-in conventional pacemaker to restabilize the heart's rhythm. If that fails, it delivers a small defibrillating electrical shock to the heart. In an extreme case, it resorts to a far stronger shock to reset the heart rate.

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defibrillation

de·fib·ril·la·tion / dēˌfibrəˈlāshən/ • n. Med. the stopping of fibrillation of the heart by administering a controlled electric shock in order to allow restoration of the normal rhythm. DERIVATIVES: de·fib·ril·late / dēˈfibrəˌlāt/ v.

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defibrillator

defibrillator (dee-fib-ri-lay-ter) n. the apparatus used for issuing a measured electrical current to a patient's heart in defibrillation. Defibrillators may be semi- or fully automated to recognize abnormal rhythms and to deliver the appropriate shock, fully operator-dependent, or implanted into the patient's body like a pacemaker.

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defibrillation

defibrillation (dee-fib-ri-lay-shŏn) n. administration of a controlled electric shock to restore normal heart rhythm in cases of cardiac arrest due to ventricular fibrillation. See defibrillator.

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