Defibrillation and the upper limit of vulnerability to fibrillation in a transthoracic Guinea pig model

• Published in: Journal of electrocardiology 1999-04, Vol.32 (2), p.159-166
• Main Authors: Li, Hui, Malkin, Robert A
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Cardiac dysrhythmias; Cardiology. Vascular system; Data Interpretation, Statistical; defibrillation; Disease Models, Animal; Electric Countershock - methods; Electrocardiography - instrumentation; Electrocardiography - methods; fibrillation; Guinea Pigs; Heart; Male; Medical sciences; Models, Cardiovascular; tachyarrhythmias; upper limit of vulnerability; Ventricular Fibrillation - physiopathology
• ISSN: 0022-0736; 1532-8430
• DOI: 10.1016/S0022-0736(99)90094-8

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 DFT 50 (the 50% successful defibrillation voltage, 496 ± 176 V) was larger than the biphasic DFT 50 (364 ± 94 V, P < .005). The upper limit of vulnerability to fibrillation (ULV 50) (the 50% successful induction voltage) was correlated with the DFT 50 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.