[Aortic wall distensibility and the structure and function of the left ventricle in aged persons with isolated systolic hypertension].

UNLABELLED

The number of old persons (over 65 years) with arterial hypertension is in a steady increase [1]. Such finding is mainly related to patients with isolated systolic hypertension. They present more than 60% of old persons with arterial hypertension [2]. Isolated systolic hypertension can be defined as increased systolic blood pressure to the value more than 160 mmHg and diastolic pressure to 90-95 mmHg [4, 5]. It has been suggested that the pathologic basis of this entity is in a decreased distensibility of aorta and great arteries. In patients with isolated systolic hypertension we studied the correlation between decreased aortic distensibility and systolic arterial blood pressure value. We also evaluated changes in the left ventricular structure and function during this type of hypertension.

PATIENTS AND METHODS

We examined 59 patients older than 65 years. They were divided in two subgroups. First subgroup: 38 patients (74 +/- 11 years) with isolated systolic hypertension (ISH) and the second subgroup: 21 normotensive persons (NT) (73 +/- 6 years). Aortic distensibility was calculated by the formula: Aortic dystensibility = difference between aortic diameters/diameter aortae in diastole x pulse pressure. The ascending aortic diameters were measured 4 cm above the aortic valve by two dimensional echocardiography and pulse pressure was measured simultaneously by sphingomanometry. Using M-mod and two-dimensional echocardiography we measured end-diastolic (EDD) and end-systolic (ESD) left ventricular diameters and thickness of interventricular septum (IVS) and posterior wall (ZZ). We calculated the ejection fraction (EF) using Teichole formula. Changes in left ventricular structure were expressed by sum of interventricular septum and posterior wall thickness and left ventricular mass. We calculated left ventricular mass using the following formula: MLK = /EDD + IVS + ZZ)3 - EDD/ x 1.05. By pulse Doppler echocardiography we measured the peak velocity of the left ventricular filling (VE) and calculated the ratio between early and late peak velocity (VE/VA).

RESULTS

Aortic distensibility was significantly lower in patients with isolated systolic hypertension than in normotensive subjects (0.10 +/- 0.02 x 1/100 1/mmHg vs 0.24 +/- 0.04 x 1/100 1/mmHg; p < 0.05). Such findings are presented in Table 1. At the same time, we found a significantly inversed correlation between aortic distensibility and systolic blood pressure value in patients with isolated systolic hypertension (r = 0.67; p < 0.05). From Table 2 it is visible that there were no significant differences between left ventricular diameter and mass in hypertensive patients. The sum of interventricular septum and posterior wall thickness was significantly greater in patients with isolated systolic hypertension than in normotensive patients (2.19 +/- 0.5 cm v.s. 1.93 +/- 0.4 cm; p < 0.05). This finding is also presented in Table 2. We found no statistically significant differences among the ejection fraction values in the studied subgroups (Table 3). The peak velocity of early filling and the ratio of early to late peak velocities were significantly lower in the hypertensive subgroup (0.4 m/s v.s. 0.54 m/s; p < 0.05; 0.69 v.s. 0.76; p < 0.05) (Table 3).

DISCUSSION

In old persons with isolated systolic hypertension we found that aortic distensibility was significantly lower in comparison to normotensive subjects of the same age. Such finding supports the hypothesis that the reduced aortic distensibility is the cause of isolated systolic hypertension. At the same time, we found the inversed correlation between aortic distensibility and the mean systolic blood pressure value. Aging has an effect on reduction of aortic and great vessels distensibility. Thus, it causes arterial hypertension which changes the elastic properties of aorta. It is still questionable in which degree the systolic blood pressure value compromises the elastic properties of aorta. (ABSTRACT TRUNCATED)