CONTACT: BECKY SOGLIN
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-6660; fax (319) 335-9917
Release: April 12, 1999
UI studying new defibrillator to treat atrial fibrillation
IOWA CITY, Iowa -- Researchers at the University of Iowa
are leading a nationwide clinical study of a new defibrillator, a device that
uses electric shock to restore normal heart rhythm. Cardiologists will use
the biphasic defibrillator in non-emergency situations to reset the irregularly
beating hearts of patients with atrial fibrillation.
The clinical study compares the new biphasic, or two-pulse,
defibrillator with the standard, single-pulse difibrillator, said Richard
E. Kerber, M.D, UI professor of internal medicine and associate director of
the Division of Cardiology. Kerber is principal investigator of the Iowa-led
study, which includes 11 other medical centers. The study is double-blind
and randomized, meaning neither the patient nor the physician will know whether
the standard or biphasic defibrillator is used until after the fact.
"We will use the new device for patients in whom the upper
two chambers of the heart are not beating regularly, but are in atrial fibrillation,
a condition of disorganized electrical function and an irregular, less effective
heart beat," Kerber said.
He emphasized that the UI will continue to use standard
defibrillators in any emergency situation involving a patient with cardiac
arrest, in which ventricular fibrillation occurs. In those cases, the lower
chambers of the heart quiver ineffectively.
A defibrillator sends an electrical pulse that momentarily
stops the heart's irregular, disorganized electrical activity, Kerber explained.
The extremely brief pause then allows the heart to begin beating again in
a normal rhythm.
A standard defibrillator delivers a single spike of electrical
current. The biphasic defibrillator delivers two spikes, a positive pulse
followed by a negative pulse. It also uses substantially less energy than
a standard defibrillator.
He added that patients with atrial fibrillation often
know when they need to seek treatment. "These patients have an irregular heartbeat
and feel other symptoms typically associated with heart conditions, such as
shortness of breath or palpitations," he said. The condition is usually not
After receiving treatment for atrial fibrillation, patients
usually may return home within one to two hours.
Kerber said the biphasic waveform is already used in automated
defibrillators to treat ventricular fibrillation. These emergency devices
are increasingly found on airlines and in places, such as hotels, where large
numbers of people gather. Kerber served as chair of an American Heart Association
task force to promote the use of these automated defibrillators.