Ventricular fibrillation frequency characteristics are altered in acute myocardial infarction.
OBJECTIVE
Future automated external defibrillators are being designed to direct rescue efforts (chest compressions first vs. defibrillation) by inferring the duration of ventricular fibrillation based on its waveform characteristics such as frequency content. This approach assumes that the ventricular fibrillation waveform is an appropriate surrogate for ventricular fibrillation duration and is not affected by structural heart disease. We hypothesized that an acute myocardial infarction may alter the frequency content of ventricular fibrillation.


METHODS
Animal intervention study with comparison to control group.


METHODS
University animal laboratory.


METHODS
Twenty-seven swine.


METHODS
Acute myocardial infarction was induced by occlusion of the mid-left anterior descending artery. Ventricular fibrillation was induced in swine with acute myocardial infarction and control swine.


RESULTS
Ventricular fibrillation was induced in 11 swine with an acute myocardial infarction and in 16 control swine. Ventricular fibrillation waveforms were analyzed for mean, median, and dominant frequency, as well as bandwidth and amplitude. All frequency characteristics were significantly (p < .001) altered in swine with acute myocardial infarction compared with controls. Specifically, these characteristics were significantly depressed and varied little over time in swine with acute myocardial infarction compared with controls.


CONCLUSIONS
These data establish that ventricular fibrillation during an acute myocardial infarction has an altered frequency content and time evolution compared with ventricular fibrillation without coronary obstruction. Frequency characteristics such as mean, median, dominant, and bandwidth show little variation in time after an acute myocardial infarction and are not suitable surrogates for ventricular fibrillation duration. These findings have important implications for the development of "smart" automated external defibrillators designed to determine duration of ventricular fibrillation from the waveform characteristics.
Indik
Julia H
JH
The Sarver Heart Center, The University of Arizona College of Medicine, Tucson, AZ, USA. jindik@email.arizona.edu
Donnerstein
Richard L
RL
Berg
Robert A
RA
Hilwig
Ronald W
RW
Berg
Marc D
MD
Kern
Karl B
KB
D000818:Animals; D016887:Cardiopulmonary Resuscitation; D047548:Defibrillators; D004562:Electrocardiography; D006321:Heart / Q000503:physiopathology; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D013552:Swine; D014693:Ventricular Fibrillation / Q000209:etiology / Q000503:physiopathology*