A wearable defibrillator
can prevent sudden death in people with dangerous arrhythmias, according
to research presented at the American Heart Association's Scientific
Sessions 2011.
A wearable defibrillator can prevent sudden
death in people with dangerous heart arrhythmias, according to research
presented at the American Heart Association's Scientific Sessions
2011. Almost 92 percent of patients with potentially lethal arrhythmias
survived to hospital discharge with the devices' aid.
Wearable cardioverter defibrillators are used by people who may
be at higher risk for sudden cardiac arrest, including those with
weakened heart function, awaiting cardiac transplant or with a condition
that prevents or delays them from receiving an implanted defibrillator.
The device monitors heart rhythm, emits alarms if a serious arrhythmia
occurs, delivers an electric shock to the heart if needed and alerts
bystanders to help if the heart's electrical activity has stopped.
About 5,000 patients are using wearable defibrillators at any one
time, usually for about 60 days, said Vincent N. Mosesso Jr., M.D.,
professor of emergency medicine at the University of Pittsburgh
School of Medicine and principal investigator of the study.
"In these patients, the wearable defibrillator is a non-invasive
'insurance policy' against sudden arrest during their vulnerable
period," he said.
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.
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.
Only about 7 percent of people in the United States who have sudden
cardiac arrest outside the hospital survive to hospital discharge,
and only about 21 percent who have them in the hospital survive
to discharge.
"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," Mosesso said. "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."
Co-authors are: Jie Li, M.S.; Douglas Landsittel, Ph.D. and Leonard
I. Ganz, M.D. Author disclosures are on the abstract.
ZOLL LifeCor of Pittsburgh, which makes the wearable defibrillator
used in the study, funded the research.
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