A Tissue Characterization Study

Ultrasonic backscatter of myocardial walls is directly related to the morphometrically evaluated collagen content in humans. The integrated backscatter is also increased in hypertrophic cardiomyopathy, whereas it gives normal values in the physiological hypertrophy of elite athletes. We assessed the quantitatively evaluated myocardial reflectivity in 46 mild to moderate, clinically uncomplicated essential hypertensive patients, with echocardiographically assessed normal regional and global left ventricular function, and 22 ageand sex-matched normotensive control subjects. With an echo prototype implemented in our institute, we performed an on-line radiofrequency analysis to obtain quantitative operator-independent measurements of the integrated backscatter signal of the ventricular septum and posterior wall. The integrated values of the radiofrequency signal of myocardial walls were normalized for those of the pericardia! interface and expressed as a percent (integrated backscatter index). Hypertensive patients and control subjects differed in mean blood pressure (119±11 versus 95±5 mm Hg, p<0.001) and left ventricular mass index (134±31 versus 105±21 g/m, p<0.00l). However, integrated backscatter index overlapped for both the septum (28±17% versus 25±6%,/>=NS) and the posterior wall (13±7% versus 13±4%,/?=NS). In the hypertensive group, there was no detectable correlation between septal integrated backscatter index and either septal thickness (r=—0.26, p=NS) or mean arterial pressure (r=— 0.14, p=NS). Hypertensive patients showed a normal pattern of quantitatively assessed ultrasonic backscatter, even in the presence of left ventricular hypertrophy. This suggests that, in the absence of overt cardiac dysfunction, disproportionate connective tissue growth does not necessarily accompany the compensatory hypertrophic response to arterial hypertension in humans. (Hypertension 1993;21:329-334)