CHANGES IN LEFT-VENTRICULAR DIASTOLIC FILLING DURING THE DEVELOPMENT OF LEFT-VENTRICULAR HYPERTROPHY - OBSERVATIONS USING DOPPLER ECHOCARDIOGRAPHY IN A UNIQUE CANINE MODEL

To examine changes in diastolic left ventricular filling during the development of left ventricular hypertrophy, serial pulsed Doppler echocardiographic studies were performed in a canine model of left ventricular hypertrophy induced by neurogenic pressor episodes. This model is unique since left ventricular hypertrophy develops without sustained hypertension. The neurogenic pressor episodes produced progressive increases in left ventricular mass of 17% by 3 weeks (p < 0.03) and of 23% by 9 weeks (p < 0.001). During the course of hypertrophy development, there were no changes in resting heart rate, blood pressure, left ventricular volumes or ejection fraction, or end-systolic wall stress. However, peak early filling (peak E) velocity decreased from 65 +/- 5 cm/sec to 53 +/- 4 cm/sec by 3 weeks (p < 0.05) and remained depressed at 9 weeks. In addition, peak E/A (the ratio of early to late peak filling) decreased by 3 weeks (p < 0.01) and the contribution of atrial filling to total left ventricular diastolic filling increased by 9 weeks (p < 0.005). There were significant correlations between the changes in left ventricular mass and the change in peak E velocity at 3 weeks (r = -0.92, p < 0.001) but not at 9 weeks. These data indicate that left ventricular filling abnormalities occur early in the course of the development of left ventricular hypertrophy, are not a result of loading alterations related to sustained hypertension, and do not change significantly following increasing stages of hypertrophy.