ECHOCARDIOGRAPHIC EVALUATION OF SIZE, FUNCTION, AND MASS OF NORMAL AND HYPERTROPHIED RAT VENTRICLES

The noninvasive evaluation of cardiac structure and function in small animals would provide a means for investigators to repeatedly evaluate treatment effects at various stages of experimental protocols. In thi s study, commercially available echocardiographic and Doppler equipmen t was utilized to evaluate hypertrophied (HYP) and normal (SH) rat hea rts. Surgically induced renovascular hypertension was used to produce a 35% increase in left ventricular (LV) weight in HYP relative to SH h earts. A commercially available echocardiographic system with integral Doppler capabilities and a 7.5-mHz single-crystal mechanical transduc er was used to obtain parasternal long- and short-axis images of HYP a nd SH hearts in anesthetized animals. HYP hearts were found to have no rmal systolic function, as evidenced by preserved LV systolic and dias tolic dimensions and volumes as well as fractional shortening and ejec tion fraction. HYP hearts demonstrated a 62% increase in their echocar diographically measured LV posterior wall thicknesses and a 44% increa se in calculated ventricular mass. Both parameters were reliable in pr edicting the presence and degree of left ventricular hypertrophy. Dopp ler flow velocities through the aortic root and pulmonic valve did not differ between groups, again suggesting preserved LV systolic perform ance. These results indicate that two-dimensional echocardiography pro vides a useful means to noninvasively evaluate cardiac structure and f unction in rats.