Ventricular wall thickness and volume during hemodynamic collapse produced by AC leakage current

Medical equipment can unintentionally allow the flow of power line current through the patient causing complete hemodynamic collapse without fibrillation. This study tests the hypothesis that static wall thickening accompanies AC induced collapse via an isovolumic state. In 3 dogs, we delivered AC current stimulation ranging from 10-160 Hz and 10-1000 μA to the right ventricle. A steerable, quadripolar catheter was placed in the apex of the left ventricle and deflected towards the basal region to measure left ventricular volume. Two dimensional, short-axis ultrasound images of the LV endocardial walls were recorded to measure wall thickness. Our results indicate that wall thickness during collapse is significantly greater than during systole (Δ thickness =11.7±12 mm, p<0.001) and diastole (Δ thickness=23.6±13 mm, p<0.001). In addition, the volume of the left ventricle is significantly smaller during collapse than the average volume during normal sinus rhythm (Δ impedance=0.152±0.006 no units, p<0.001).