Does hyperkinetic circulation constitute a pre-hypertensive stage? A 5-year follow-up of haemodynamics in young men with mild blood pressure elevation.

In a previous haemodynamic examination, 44 young men (18-22 years) with blood pressure elevation above the 98th percentile, mean arterial blood pressure (MAP) greater than or equal to 95 +/- 6 mm Hg, showed an increased cardiac index (dye-dilution) and an enhanced resistance at maximal vasodilation of the hand (venous occlusion plethysmography during hyperaemia). This latter finding suggested arteriolar wall hypertrophy. However, the subgroup with the highest cardiac index (greater than or equal to 3.86 1 min-1 x m2) (n = 18) displayed normal vascular resistance at maximal dilation in comparison with the normotensive control group (n = 29). Consequently, functional signs of arteriolar hypertrophy were restricted to individuals with normal or low cardiac index. At the re-investigation 5 years later, a significant reduction in blood pressure was observed in the normotensive control group (MAP: from 88 +/- 7 to 85 +/- 7 mm Hg, P less than 0.05). There was no change in individuals with initially elevated blood pressure. Furthermore, cardiac index fell significantly with time in this latter group. Thus, the blood pressure elevation in the hypertensive group, previously mainly dependent on high blood flow was, 5 years later, more related to an increased total peripheral resistance, (delta total peripheral resistance = 8%). However, no definite evidence indicating development of hypertrophy of the resistance vessels of the hand was observed during the follow-up period. Since the hyperkinetic subgroup did not display a concomitant fall in blood pressure with cardiac output, our results do not support the theory that the hyperkinetic form of borderline hypertension is a temporary phenomenon, explained by the inclusion of anxious individuals afraid of the experimental situation. Hyperkinetic hypertension may be the initial phase of sustained hypertension in a subgroup of the future hypertensive population.