Early changes and rules of cardiac function and hemodynamics in rabbits with experimental myocardial contusion

摘要

Objective: To study changes and rules of the left ventricular functions in rabbits with myocardial contusion through parallel functional analysis by using echocardiography combined with cardiac catheter intervention. Methods: Thirty healthy rabbits were selected and impacted to make moderate or severe myocardial contusion by BIM-II biomedical impact machine. The changes of hemodynamics and cardiac systolic and diastolic functions were respectively observed before injury and 1, 4, 8 and 24 hours after injury. Results: After myocardial contusion, the heart rate, systolic pressure, diastolic pressure and mean arterial pressure of rabbits decreased remarkably at 1-4 hours. The left ventricular end-systolic pressure ( LVESP), the maximum increasing rate of the left intraventricular pressure (+dp/dtmax), isovolumic pressure (IP) and the maximum systolic velocity of the left ventricle (Vmax) also decreased markedly. And then these parameters recovered to the level of preinjury at 8-24 hours. The left ventricular end-diastolic pressure ( LVEDP), the rate of the left intraventricular pressure (-dp/dtmax) and the decreasing time constant of the left intraventricular pressure (T) increased remarkably 1 hour after myocardial contusion, and did not decrease until 8 hours after myocardial contusion. Detection by echocardiography showed that ejection fraction of the left ventricle markedly decreased at 24 hours after myocardial contusion, while the systolic volume decreased obviously as early as 1 hour after myocardial contusion, at 4-8 hours it recovered a little and again decreased at 24 hours. The end systolic volume and end diastolic volume increased after myocardial contusion, but statistical significance was only seen at 8 hours after myocardial contusion. Conclusions: Cardiac functions of the left and right ventricles are markedly injured after myocardial contusion with disorders of the left ventricle diastolic function and of the right ventricle systolic function as the dominant injury. While the systolic function of the left ventricle can recover. Echocardiography shows clinical importance in detection of early injuries of cardiac functions.