Electrical and morphological changes of cardiac pressure over-load left ventricular hypertrophy in rabbits / 第二军医大学学报

ABSTRACT

Objective To observe whether the changes of electrocardiogram (ECG) is earlier than the morphological changes of ultrasonic cardiogram (UCG) during the development of cardiac pressure over-load left ventricular hypertrophy (LVH) in rabbits, so as to discuss the value of ECG in the early diagnosis of hypertensive LVH. Methods Forty male Japanese rabbits were randomly divided into experimental group (n=25) and control group (n=15). Rabbits in the experimental group were used to establish cardiac pressure over-load LVH model by subtotal ligation of suprarenal abdominal aorta. The control group received the same treatment as that in the experimental group except for the coarctation of abdominal aorta. Before operation and the 2nd, 4th, 6th, and 8th week after operation, 12-lead ECG were recorded to measure R-wave and QRS complex wave amplitude, heart electric axis, QRS duration and QTc period; UCG was performed to detect the thickness of left ventricular inferior wall (LVIW), posterior wall (LVPW) and interventricular septum (IVS), left ventricular end diastolic diameter (LVDd), left ventricular end systolic diameter (LVDs), E/A ratio and left ventricular ejection fraction (LVEF). Before operation and the 8th week after operation, chest X-ray examination was performed to detect cardiothoracic ratio. Then all the rabbits were sacrificed. Left ventricular mass indices (LVMI) were measured and cardiac pathological examination was performed. Results The blood pressure of rabbits increased gradually after operation in the experimental group, the cardiothoracic ratio and LVMI aggrandized, and the cardiomyocytes hypertrophy, denaturalization or necrosis were observed under microscope in the experimental group. The thickness of LVIW, LVPW and IVS of rabbits in the experimental group increased gradually, and the E/A ratio decreased gradually, showing significant difference when compared to those of the control group at the 4th week (P0.05). Conclusion During the development of cardiac pressure over-load LVH of rabbits, the electrical changes of ECG are earlier than the morphologic changes of UCG, which indicates that ECG may has a value for early diagnosis of the hypertensive LVH.