Does hypertension or aging modulate directional shortening of the left ventricular midwall?

It is unclear whether aging or hypertension modulates directional contractile function of the left ventricular (LV) wall. We investigated LV midwall shortening and thickening in 35 normal subjects and in 15 patients with mild-to-moderate systemic hypertension (HT) using 2-dimensional echocardiography. The normal subjects were divided into 3 subgroups according to age: 13 subjects below 30 years, 12 subjects over 31 and below 59 years, and 10 subjects over 60 years. In normal subjects of all ages, no significant difference was observed between meridional shortening (%Lm = 16.3 +/- 2.4) and circumferential shortening (%Lc = 17.1 +/- 4.0), and a significant increase in the short-axis cross-sectional area (CSA) of the LV wall at end-systole was observed (p < 0.001). No significant differences with age were found in the measurements, except that %Lc/%Lm was reduced (p < 0.05) in the elderly subgroup. In HT, all measured parameters, i.e., %Lm, %Lc, %Lc/%Lm, wall thickening, and the change in CSA, showed no difference from those of normal subjects. We conclude that the shortening of the normal LV midwall is similar in both meridional and circumferential directions, and that aging and mild-to-moderate HT do not significantly affect this characteristic, when echocardiographic measurements are taken at rest at end-diastole and end-systole. This observation may be applied to simulation analyses of basic LV mechanics, such as the finite element method.