Aortic rigidity and plasma catecholamines in essential hypertensive patients

Aortic rigidity, plasma noradrenaline and adrenaline, and hemodynamic parameters were measured in 48 essential hypertensive patients, 25 younger than 45 (Group I) and 23 of 45 years and over (Group II). Aortic rigidity was determined by the ratio of pulse pressure over stroke volume. Aortic rigidity and hemodynamic parameters were also determined after combined alpha-beta receptor blockade induced by Labetalol (mg 100 IV) or by Propranolol (mg 10 IV) plus Phentolamine (mg 10 IV). The aortic rigidity index was significantly higher in Group II, systolic arterial pressure being significantly higher. All other data, including plasma noradrenaline and adrenaline, were not significantly different in the two groups. In Group II a significant correlation (r = 0.62) was noted between aortic rigidity indexes and plasma noradrenaline values. The alpha-beta receptor blockade induced a decrease of aortic rigidity particularly in Group II, owing to a more marked decrease of systolic arterial pressure. A highly significant correlation was noted in Group II between the changes in aortic rigidity index and the basal plasma noradrenaline levels (r = 0.81). Therefore, the aortic rigidity in essential hypertensive patients older than 45 is influenced by the sympathetic nervous system activity, as judged by plasma noradrenaline levels. This influence seems related to an increase with age of aortic responsiveness to sympathetic stimulation.