Left ventricle myocardial mechanics and textural properties in patients with Williams syndrome

Abstract

To study left ventricular mechanics and textural properties in patients with Williams syndrome to define the impact of left ventricular hypertrophy on the functional findings. Echocardiography was performed in 16 Williams syndrome patients (aged 1-25 years, mean 10 +/- 6 years), four with associated supravalvular aortic stenosis and seven with systemic hypertension. Fifteen age- and body surface area-matched subjects were selected as control group. Particularly, left ventricular geometry, myocardial contractility [midwall rate-corrected circumferential fiber shortening/end-systolic meridional wall stress relationship (sigmaes)] and left ventricular diastolic function (mitral flow pattern and isovolumic relaxation time) were defined. In addition, integrated backscatter (IB) analysis intensity (IntIB) and cyclic variation (CVIB) were assessed for an ultrasonic myocardial characterization. Left ventricular hypertrophy was demonstrated in nine patients (56%) and abnormal left ventricular remodeling in ten patients (62%). Particularly seven of seven hypertensive patients and three of four patients with supravalvular aortic stenosis had abnormal remodeling; left ventricular geometry was normal in patients without hypertension or supravalvular aortic stenosis. In addition, midwall rate-corrected circumferential fiber shortening/(sigmaes) relationship was within the normal range in all patients. At integrated backscatter analysis, Williams syndrome patients showed, both at interventricular septum and posterior wall, reduced CVIB (9.36 +/- 2.16 versus 10.3 +/- 1.3 and 8.65 +/- 2 versus 10.5 +/- 1.1). Compared to Williams syndrome patients without left ventricular hypertrophy (7/16), those with left ventricular hypertrophy (9/16) showed decreased mitral E/A ratio (1.32 +/- 0.09 versus 1.62 +/- 0.02), increased isovolumic relaxation time (68 +/- 7 versus 53 +/- 7) and increased IntIBS at interventricular septum (-27.3 +/- 0.07 versus -34 +/- 5). Our data obtained in young Williams syndrome patients show that: (i) mild left ventricular functional and textural abnormalities may be detected also in absence of significant supravalvular aortic stenosis and/or hypertension; (ii) significant left ventricular hypertrophy may develop since childhood; (iii) differences in left ventricular remodeling and/or degree of left ventricular hypertrophy may occur. Further studies are required to define the real impact of the functional abnormalities on the natural history in patients with Williams syndrome.