Echocardiographic Study on Left Ventricular Filling Pattern in Hypertension

Abstract

In order to evaluate the filling characteristics of the left ventricule (LV) in the hypertension (H-group) were cpmpared to 16 patients with idiopathic hypertrophic cardiomyopathy (HCMgroup)and 50 normal subjects (N-group) by echocardiography. According to the amount of LV wall thickness (sum of interventricular septum and LV posterior wall thickness), H-group was divided into three groups: H1 group consisted of 20 cases, H2 of 25, H3 of 19; values of wall thickness were 2.5 cm or less,2.6 to 3.1 cm and 3.2 cm or more, respectively. N-group was subdivided into four age groups in order to assess the effect of age on LV geometry and hemodynamics: Ni (29y or less), N2 (30-39y), N3 (40-49y) and N4 (50y or more).
Mitral valve and LV echocardiograms were analyzed by a digitizer-computer sy stem to obtaine isovolumic relaxation time (IRT), diastolic descent rate of mitral valve (DDR), LV dimension, wall thickness, LV posterior wall motion (PWV) and LV volume change. LV diastolic time was divided into three phases; rapid, slow and atrial filling phases (RFP, SFP, AFP respectively). Filling rate (FR) and ratio of the fractional-filling volume to the total LV filling (FF)in each phase were calculated.
LV diameter was slightly smaller in H-groups and remarkably smaller in HCM-group than in N-group. There were no significant differences in the heart rate, P-Q interval and systolic contractile indices among the groups. Mean and maximal PWV in diastole were significantly reduced in H and HCM groups, and maximal rate of LV circumferential fiber lengthening was reduced in H2 and H3 groups as compared to N-group. In H and HCM groups, longer IRT and slower DDR were noted. Filling fractions in RFP and AFP (RFF, AFF) were 64.5and 22.5% in N,54.9 and 28.5% in H2,41,6 and 43,6% in H3,65.7 and 19.8% in HCM group, respectively. In N and H groups, the values of RFF and AFF were signifincantly correlated with LV wall thickness. (r= -0.69, r=0.72, respectively) As for mean filling rates of RFP and AFP (RFR, AFR), RFR were slower and AFR faster in H groups than in N group, while both filling rates were significantly slower in HCM group.
In normal subjects, N4 (2.2 cm) had thicker LV wall than N1 (1.9 cm), while the LV volume and diameter were same in both groups. IRT was more prolonged in N4 than in Ni. As to concerning to filling fraction, N4 group had reduced RFF (60%) and augmented AFF (28%) as compared to N1 group who had 67 and 20%, respectively.
These findings indicate that 1) in the normal heart, LV wall thickens with larger LV volume/mass ratio, and LV filling in the early diastole becomes impeded with aging; 2) in the hypertensive heart, LV early diastolic filling is impeded as LV hypertrophy asvances and the atrial kick mechanism works more forcefully and effectively to compensate the impaired filling; 3) in the hypertrophic cardiomyopathic heart, the atrial filling to the ventricle is not sufficient to compensate the reduced filling in the early diastole, probably because the LV cavity is disproportionately small as compared to the marked hypertrophic wall, and the left ventricular myocardium has a disarray in arrangement of cardiac muscle cells.