Abstract 18169: Identifying Early Changes in Myocardial Microstructure via Ultrasound in Hypertensive Heart Disease
BACKGROUND: The transition from healthy myocardium to hypertensive heart disease is characterized by a series of poorly understood changes in myocardial tissue microstructure. Incremental alterations in the orientation and deformation of myocardial fibers can now be assessed using advanced techniques in ultrasonic image analysis.
METHODS: We used a modified approach to non-invasively assess left ventricular (LV) myocardial microstructure, based on sonographic signal intensity analysis of the inferolateral pericardium (viewed in the parasternal long-axis view of B-mode echocardiographic images). We defined the transmission intensity (TI), an indirect measure of the intensity reflection coefficient at the myocardial-pericardial interface, as 1 - (P/256) where P is the 25th percentile value of pericardial signal intensity on a 256 scale. We determined the extent to which TI is able to differentiate between normal myocardium and hypertensive heart disease in a mouse model and in humans.
RESULTS: As shown in the Figure, 7-week echocardiographic measurements of TI were significantly different between groups of mice that underwent fixed aortic banding (n=3) versus sham procedure (n=3) at baseline. Similarly, measurements of TI were significantly different between individuals with uncomplicated essential hypertension (N=30, age 54±3 yrs, 47% women) and healthy controls (N=28, age 53±9 yrs, 60% women). Although there was a trend in higher relative wall thickness in hypertensive individuals compared to controls (P=0.09), there was no difference between these groups in LV mass (P=0.67) or LV wall thickness (P=0.26).
CONCLUSION: Based on sonographic signal intensity analysis, the TI is an accessible, non-invasive measure that appears to differentiate normal LV microstructure from myocardium exposed to chronic afterload stress. The TI may be a particularly sensitive measure of myocardial changes that occur early in the course of disease progression.
- © 2013 by American Heart Association, Inc.