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.
ABSTRACT
Objective: To explore the effect of exercise preconditioning (EP) on pathological cardiac hypertrophy and heart failure (HF) in pressure over-loaded experimental rats. Methods:A total of 60 SD rats at the age of 6 weeks were randomly divided into 3 groups, n=20 in each group. Sham-operation group, Transverse aortic constriction (TAC) group and EP + TAC group. The cardiac function and structure were evaluated by echocardiography, patholgical changes and HF biomarkers were examined for EP effect at 4 and 8 weeks after TAC. Results:Compared with Sham-operation group, the cardiac function and structure had obvious changes in the other 2 groups. Compared with TAC group, the ejection fraction in EP+ TAC group increased 15%, the heart weight index and left ventricular weight index decrease 15.7%and 20%respectively at 8 weeks after TAC, all P Conclusion: EP may improve cardiac pathological hypertrophy in pressure over-loaded rats at the early stage, and delay the heart failure process.