This issue begins with a review by Dr. Geneviève Nguyen who provides a comprehensive review of the history of the renin-angiotensin system with a specific focus on pro-renin and its receptor. The latter, an unique receptor type, has received a great deal of recent attention and is now at the stage of scientific maturity to warrant such a detailed discussion. Dr. Nguyen provides the background for understanding the current status of knowledge about this receptor as well as preparing the stage for future research contributions in this area. Olafiranye and colleagues have pursued the issue of the vascular effects of antihypertensive therapy by studying aortic wave reflection in patients receiving beta adrenergic blockers. They observed increased aortic augmentation index despite similar brachial thickness and pressures. These findings raise the issue of discrepant central and peripheral blood pressures and the role of changes in heart rate and stroke volume. A third study on vascular elasticity and biomarkers is presented by Valappil and colleagues utilizing the subjects involved in the CARDIA Study. These observations found a correlation between several biomarkers and the elasticity of large and small vessels as measured by the pulse wave velocity approach using a modified Windkessel model.
Dr. Gerald Berenson reports new information from the long-running Bogalusa Heart Study which seeks to identify the antecedents of adult cardiovascular disease by studying and following children into adulthood. While an increase in heart rate has been shown to be a risk factor for cardiovascular events in adults, a careful study of the role of heart rate and blood pressure in children and their long-term implications has not previously been reported. The Bogalusa Study examined the pressure-rate product in this biracial population longitudinally from childhood to adulthood and observed differences that may be relevant to the subsequent occurrence of cardiovascular disease.
While a “non-dipping” pattern of nocturnal blood pressure was shown to be associated with factors contributing to cardiovascular and renal events, there have been few long-term studies to document this association directly. Verdecchia and colleagues provide a 7-year follow-up confirming that non-dippers have significantly more cardiovascular events and a greater mortality than those in whom the normal nocturnal decline is observed, independent of the technique used for analysis of the diurnal blood pressure changes. These findings have far-reaching and compelling implications for antihypertensive therapy.
Health issues are a major focus for the political candidates during this American election year. Certainly the hypertension detection, treatment and control rates remain abysmal among the American population and there is a strong emphasis, based on current data, to suggest that our goals for blood pressure should be even lower than they have been in the past. New and more aggressive approaches will be required to improve these unsatisfactory results and to reduce cardiovascular, renal, and cerebral events further. In the United Kingdom a new payment paradigm based on blood pressure numbers has been shown to be effective in improving blood pressure control as reported by practitioners. Dr. Norman Campbell succinctly outlines the poor blood pressure control rates observed in Canada and describes the techniques that were used to improve them. After mobilizing both governmental and non-governmental resources to attack the low rate of hypertension recognition, treatment, and control, in a short period of 4 years, a measureable improvement was observed. This model is a useful one to incorporate in the public health approaches to hypertension in other countries.
Jessup and colleagues utilized the rat model to examine the effects of “low-dose” diuretic treatment on the renin-angiotensin system. While the metabolism of rats differs from that of humans, the dose of 1.5 mg/kg/d of hydrochlorothiazide used in their study would represent a 90 mg daily dose in the 60 kg human. They observed no change in blood pressure in the normotensive control rats confirming the fact that homeostatic mechanism in normotensive animals operate effectively. The investigators also suggest that the increase in renin activity resulting from diuretic-induced volume depletion may have prevented the fall in blood pressure in the normal animals. However, as anticipated, blood pressure was reduced by diuretics in the hypertensive animals.
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