Arterial Hemodynamics in Prehypertensives

Abstract

Compared to age-matched normotensive adults, those with essential hypertension have been shown to have distinct arterial hemodynamic abnormalities consisting of increased peripheral resistance, pulse wave velocity, and wave reflection magnitude as well as decreased wave reflection time and aortic compliance. These abnormalities are further exacerbated by beta-adrenergic blockade. To see if there are similar hemodynamic abnormalities that antedate the onset of fixed hypertension, we compared age-matched normotensives with prehypertensives selected from patients undergoing diagnostic cardiac catheterization. Ascending aortic pressure and flow were measured with a micromanometer and flow velocity sensor in the baseline state and after beta-adrenergic blockade. In the baseline state the prehypertensive compared to the normotensive group had elevated blood pressure, resistance, left ventricular end-diastolic pressure (LVEDP), and wave reflections. Beta-adrenergic blockade increased resistance, LVEDP, and wave reflections in both groups. Some of these findings are the same as those we previously reported in young persons with established, essential hypertension. The differences in LVEDP and wave reflections, both in the baseline state and after beta-blockade, were still present in subgroups with no differences in blood pressure. Hence, the elevated wave reflections in prehypertensives do not appear to be directly related to the level of blood pressure. These results support the notion that the elevated blood pressure in hypertension may represent a later manifestation of an already abnormal vascular system rather than the vascular abnormalities resulting from hypertension. Consequently, even before blood pressure becomes elevated, early diagnosis and treatment of the vascular abnormalities in prehypertensives may be warranted.

Pulmonary hemodynamics and wave reflections in adults with atrial septal defects

“…We estimated mixed venous sO2 as (3 ϫ SVC sO2 ϩ IVC sO2)/4, and as with the scaling factor for PBF, we assumed that pulmonary venous and femoral artery sO2 were the same. The remaining calculations are essentially identical to those we have previously reported (33,40,41). Briefly, the analog records were digitized at a rate of 250 Hz and analyzed with a custom algorithm on a personal computer.…”

“…We calculated all hemodynamic parameters using several beats for each patient under baseline and NP conditions. Based on our experience with the coefficients of variation for the directly measured and derived parameters from many analogous studies in the systemic arterial system (33,40), we averaged data from a minimum of four (mean, 12.7, range, 4 -35) acceptable beats to obtain what we consider to be representative findings for each patient in normal sinus rhythm.…”