The cardiac defibrillator is a life-saving device used to give the heart a controlled electric shock to jolt it back to beating normally. According to a May 2004 study published in "Medscape Cardiology," cardiac defibrillators are best used in patients with severe types of heart conditions. The use of defibrillators in such patients can ultimately help prevent further heart damage such as sudden heart death, according to a statement released by Medscape Internal Medicine in January 2005.
Cardiac Arrest
The most common criterion for the use of a defibrillator is sudden cardiac arrest characterized by unresponsiveness, no pulse, negative breathing efforts and no visible signs of blood circulation, according to the Emergency Treatment Guidelines of Matinoba Health. Five cycles of cardiopulmonary resuscitation must be initiated to establish good oxygen and blood supply to the heart before giving the first shock using the defibrillator. After which, another set of five cycles of cardiopulmonary resuscitation must be done before doing another pulse check.
Symptomatic Ischemic Dilated Cardiomyopathy
The automatic implantable cardioverter defibrillator is a type of defibrillator installed surgically within the body. It is usually indicated for primary prevention in a patient with symptomatic ischemic dilated cardiomyopathy, a problem involving the heart muscles characterized by decreased ability of the heart to squeeze out blood, according to the Corporate Medical Policy of the BlueCross Blueshield of North Carolina. A previous history of heart attack and left ventricular ejection fraction, and 35 percent or less of blood output of the left lower chamber of the heart further warrant its use. However, installing this kind of defibrillator is usually temporarily contraindicated in patients with ongoing systemic infection. Another alternative that can be used is the vest-like, wearable cardioverter defibrillator, a defibrillator that functions like the automatic implantable cardioverter defibrillator. The only difference is that the patient will not undergo an invasive surgical procedure to benefit from this type of defibrillator.
Ventricular Tachycardia
The implantable cardioverter defibrillator and the wearable cardioverter defibrillator can also be used for secondary prevention in patients with a history of a life-threatening clinical event associated with ventricular tachycardia, the fast, pulseless heartbeat of the lower chambers of the heart. According to Corporate Medical Policy, these defibrillators sound a series of alarms whenever they detect an abnormal heart rhythm. Conscious patients simply press and hold two response buttons to prevent the occurrence of shock from the defibrillator. However, if the patient is unconscious, the defibrillator automatically delivers electrical shock therapy within 60 seconds to restore the normal rate and rhythm of the heart.
References
- Manitoba Health: Emergency Treatment Guidelines General -- Automatic External Defibrillator
- BlueCross BlueShield of North Carolina: Corporate Medical Policy -- External Defibrillators
- "Medscape Cardiology"; SCD-HeFT: Sudden Cardiac Death in Heart Failure Trial; Gruberg, L.; April 2004
- Medscape CRM News: Medicare Approves Expanded ICD Coverage Criteria
