ANALYSIS OF TRANSMURAL TREND OF MYOCARDIAL INTEGRATED ULTRASOUND BACKSCATTER FOR DIFFERENTIATION OF HYPERTROPHIC CARDIOMYOPATHY AND VENTRICULAR HYPERTROPHY DUE TO HYPERTENSION

Objectives. This study was undertaken to differentiate hypertrophic ca rdiomyopathy from hypertensive hypertrophy using a newly developed M-m ode format integrated backscatter imaging system capable of calibratin g myocardial integrated backscatter with the power of Doppler signals from the blood. Background. Myocardial integrated ultrasound backscatt er changes in patients with hypertrophic cardiomyopathy; however, it i s unknown whether ultrasound myocardial tissue characterization may be useful in differentiating hypertrophic cardiomyopathy from hypertensi ve hypertrophy. Methods. Calibrated myocardial integrated backscatter and its transmural gradient were measured in the septum and posterior wall in 31 normal subjects, 13 patients with hypertensive hypertrophy and 22 patients with hypertrophic cardiomyopathy. The gradient in inte grated backscatter was determined as the ratio of calibrated integrate d backscatter in the endocardial half to that in the epicardial half o f the myocardium. Results. Cyclic variation of integrated backscatter was smaller and calibrated myocardial integrated backscatter higher in patients with hypertrophied hearts than in normal subjects, but there were no significant differences in either integrated backscatter meas ure between patients with hypertensive hypertrophy and those with hype rtrophic cardiomyopathy. Transmural gradient in myocardial integrated backscatter was present only in patients with hypertrophic cardiomyopa thy (5.0 +/- 1.8 dB [mean +/- SD] for the septum; 1.2 +/- 1.6 dB for t he posterior wall). Conclusions. Hypertrophic cardiomyopathy and ventr icular hypertrophy due to hypertension can be differentiated on the ba sis of quantitative analysis of the transmural gradient in integrated backscatter.