[Assessment of localized hypertrophy in the basal part of the interventricular septum in the elderly].

The basal part of the interventricular septum (IVS) is known to show different hypertrophic features from those observed in the other parts of the left ventricular wall. These are considered to reflect physiological changes that occur with normal aging. However, these changes have not been carefully evaluated, and their clinical significance has not been defined. We assessed these changes echocardiographically. The subjects were patients at least 70 years of age in whom localized hypertrophy in the basal part of the IVS was seen during the whole cardiac cycle on echocardiography. The prevalence was 6.3% among 96 consecutively studied patients. All 6 patients had a history of hypertension. Echocardiographic findings were as follows: 1) the left atrium was mildly or moderately dilated, 2) there was no evidence of either dilatation or narrowing of the left ventricular cavity, 3) the left ventricular wall motion appeared normal and indices of systolic function were within normal limits in all subjects except one who had a history of myocardial infarction, 4) the angle formed by the aorta and the IVS averaged 106.7 degrees (range: 95 to 120 degrees), 5) Doppler examination showed increases in the ratio of the peak flow velocity during atrial systole to the peak flow velocity early in diastole, and 6) prolongation of the deceleration time of the flow velocity early in diastole. The last of these findings suggested left ventricular diastolic dysfunction, but peak flow velocity at the left ventricular outflow tract was normal. There was no evidence of stenosis of the left ventricular outflow tract. Localized hypertrophy in the basal part of the IVS in elderly patients could be a type of cardiac hypertrophy caused by hypertension. On echocardiography, the basal part of the IVS seemed to protrude toward the left ventricular cavity, but there was no evidence of stenosis in the left ventricular outflow tract.