Mechanical response of the left ventricle during AC induced hemodynamic collapse

Medical equipment can unintentionally allow the flow of small amounts of AC current through the patient causing hemodynamic collapse without fibrillation. This study examines the mechanical response of the left ventricle during AC induced hemodynamic collapse. Six dogs received 5 seconds of AC current stimulation ranging from 4-160 Hz and 10-1000 μA to the right ventricle. A quadripolar catheter was placed in the apex of the left ventricle to measure left ventricular volume. Short-axis ultrasound images were recorded to measure left ventricular cross sectional area and wall thickness. Our results showed that the mean volume of the left ventricle during collapse was significantly smaller (p < 0.05) than the mean volume preceding collapse. Cross sectional area also decreased significantly and wall thickness increased. This suggests that the heart assumes a contracted, systole-like state during collapse.