Hemodynamic Patterns in the Natural History of Borderline Hypertension

Abstract

This paper gives a review of cross-sectional and long-term hemodynamic studies in mild and borderline hypertension at different ages. Since the term borderline and mild are frequently used rather loosely, the selection criteria and blood pressure during the hemodynamic study should be noted. For two decades it has been assumed that subjects below 40 years of age with mild or borderline hypertension usually have a higher resting cardiac index (CI) and heart rate (HR) than normotensive age-matched controls. This assumption is supported by numerous previous and recent invasive studies in young males. However, a true hyperkinetic circulatory system with abnormally low arteriovenous oxygen difference is not typical. The whole-body oxygen consumption is increased, and cardiac output is normal when related to the oxygen uptake. Thus, the so-called whole-body autoregulation theory should not be applied to explain the chain of hemodynamic events including a fall in cardiac index and an increase in total peripheral resistance over time. Recent noninvasive studies in children and adolescents with mild or borderline hypertension have generally not demonstrated higher cardiac indexes in mildly hypertensive groups, and blood pressure increases have been due to increased total peripheral resistance. Possible explanations for these different findings in subjects supposed to be in the initial phase of essential hypertension are discussed. Our laboratory performed invasive long-term follow-up studies of central hemodynamics at rest and during exercise at 10 years and 17 years.(ABSTRACT TRUNCATED AT 250 WORDS)