Vincent N. Mosesso Jr., M.D., professor of emergency medicine at the University of Pittsburgh School of Medicine presented a study on wearable defibrillators at the American Heart Association’s Scientific Sessions 2011. Wearable cardioverter defibrillators are used by people who are waiting for a cardiac transplant or with a condition that prevents or delays them from receiving an implanted defibrillator.
The researchers gathered heart rhythm records and calls about shocks from a registry of 14,475 patients with wearable defibrillators listed from 2007 through 2009. Of those, 185 (about 1 percent) received an appropriate shock and 91.6 percent survived one or more episodes of ventricular fibrillation or ventricular tachycardia, the most common abnormal rhythms during cardiac arrest.
Wearable defibrillators delivered 223 inappropriate shocks to 213 people who weren’t experiencing ventricular fibrillation or ventricular tachycardia. However, no one died as a result. Researchers attribute the inappropriate shocks to signal noise, rapid non-VT rhythms, and rhythm misinterpretation.
Mosesso is cited in the press release:
About 5,000 patients are using wearable defibrillators at any one time, usually for about 60 days. In these patients, the wearable defibrillator is a non-invasive ‘insurance policy’ against sudden arrest during their vulnerable period. This study confirms the effectiveness of very early defibrillation as therapy for sudden cardiac arrest in high-risk patients when delivered by a wearable defibrillator. These defibrillators provide patients the critical advantage of not having to wait for a bystander or emergency responder to recognize the cardiac arrest and use an automated external defibrillator or manual defibrillator — both of which can lead to delays in treatment and markedly worse survival rates.
The wearable defibrillator used in this study is the LifeVest, made by ZOLL Medical Corporation, Chelmsford, MA.
The American Heart Association Scientific Sessions are being held from Nov 12-16 in Orlando, FL.
Flashback: The LifeVest Conspiracy
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