Defibrillation and the upper limit of vulnerability to fibrillation in a transthoracic guinea pig model.
Recent studies have shown sustained tachyarrhythmias in guinea pigs. We hypothesized that guinea pigs could be used as a model of ventricular fibrillation, focusing on defibrillation waveform efficacy and the upper limit of vulnerability to fibrillation. In 10 male guinea pigs, an esophageal/apical pacing electrode configuration was used. The electrocardiogram (ECG) and arterial blood pressure were continuously monitored. T-wave and defibrillation shocks were applied transthoracically. A modified up-down protocol was used. After up-down testing was completed, a tachyarrhythmia was induced without electrical termination. All animals died of a sustained tachyarrhythmia. The monophasic DFT50 (the 50% successful defibrillation voltage, 496 +/-176 V) was larger than the biphasic DFT50 (364+/-94 V, P < .005). The upper limit of vulnerability to fibrillation (ULV50) (the 50% successful induction voltage) was correlated with the DFT50 for both monophasic (r = .82, P < .005) and biphasic shocks (r = .88, P < .005). Its low cost and ease of handling may make the guinea pig a preferred model for some fibrillation and defibrillation studies.
Li
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Joint Department of Biomedical Engineering, The University of Tennessee-Memphis and The University of Memphis, 38152, USA.
Malkin
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RA
D000818:Animals; D003627:Data Interpretation, Statistical; D004195:Disease Models, Animal; D004554:Electric Countershock / Q000379:methods*; D004562:Electrocardiography / Q000295:instrumentation / Q000379:methods; D006168:Guinea Pigs; D008297:Male; D008955:Models, Cardiovascular; D014693:Ventricular Fibrillation / Q000503:physiopathology*