Abstract
Purpose: To evaluate the effect of anesthesia on cardiac function. Mitral inflow pattern, especially E/A ratio, is very useful in evaluating diastolic function; however, it is not easy to measure E/A in small animals like mice and rats because of the summations induced by their high heart rate. E/A can generally be measured by administering an anesthetic agent to reduce heart rate, although the effect of anesthesia on cardiac function is unclear. Methods: Sprague Dawley rats were studied by ViVid 7 (GE Healthcare, USA) with a high-frequency transducer (11.5 MHz, 234 FPS) to evaluate fractional area changes (FAC) and mitral flow pattern after step-wise increase in anesthesia. Results: The A wave gradually separated from the E wave as heart rate decreased, and E/A could be measured in all the rats when heart rate was reduced to 300 bpm. Change in fractional area decreased slightly, from 71.4 ± 4.6% to 67.6 ± 3.9%, with reduction in heart rate. Conclusion: The E/A ratio in rats could be measured after heart-rate reduction with little decrease in fractional area changes. The measure of E/A after heart rate reduction may be acceptable except in the special case of evaluating microscopic changes.
