Early diastolic regional function of the hypertrophied left ventricle

We analyzed cardiac catheterization data from 7 patients with aortic stenosis and 10 patients with nonobstructive hypertrophic cardiomyopathy to compare left ventricular regional diastolic function. Left ventriculogram in the right anterior oblique projection was analyzed by the area method, and regional wall stress and regional area were computed for 4 regions in the mid-portion of the left ventricle. For each region, we assessed the percent area changes (normalized by end-diastolic regional area) and time constant for regional wall stress decrease during the isovolumic relaxation period. Regional non-uniformity during the isovolumic relaxation period was then evaluated by standard deviations for the percent area changes and for regional time constants of the 4 ventricular regions. In patients with hypertrophic cardiomyopathy, both the standard deviations for the percent area changes and the regional time constants were greater (P < 0.05) than those in patients with aortic stenosis, suggesting the presence of pronounced non-uniformity of regional relaxation in hypertrophic cardiomyopathy. The time constant of left ventricular pressure decrease during early relaxation phase was significantly greater (P < 0.01), and the early diastolic peak filling rate of the global left ventricle was significantly smaller (P < 0.05) in patients with hypertrophic cardiomyopathy. Thus, early diastolic left ventricular regional non-uniformity was more pronounced in hypertrophic cardiomyopathy than in aortic stenosis, which was associated with the impairment of relaxation and early filling of the global left ventricle. These findings suggest that different mechanisms are responsible for diastolic dysfunction in primary versus secondary myocardial hypertrophy.