CENTRAL BLOOD-VOLUME - A DETERMINANT OF EARLY CARDIAC ADAPTATION IN ARTERIAL-HYPERTENSION

Objectives. This study was undertaken to assess the influence of the f luid volume state on cardiac adaptation to hypertension. Background. L eft ventricular hypertrophy is an important predictor of hypertensive complications. We analyzed volume status and its impact on cardiac str uctural changes in early hypertension. Methods. In 33 normotensive sub jects, 40 patients with borderline hypertension and 63 patients with e stablished essential hypertension, mean arterial pressure was measured invasively; total blood volume was measured by iodine-125-labeled pla sma albumin and hematocrit; central blood volume by indocyanine green dye dilution curve; and diastolic diameter and left ventricular mass b y two-dimensional-guided M-mode echocardiography. Results. Central blo od volume was similar to 20% higher in patients with stage I borderlin e hypertension than in normotensive sub subjects ([mean +/- SD] 3,001 +/- 663 vs. 2,493 +/- 542 mi, p < 0.05), whereas total blood volume wa s similar in all three groups. This shift in intravascular volume towa rd the cardiopulmonary circulation was accompanied by a significant in crease in diastolic diameter (5.29 +/- 0.80 vs. 4.86 +/- 0.77 cm, p < 0.05) and in left ventricular mass (239.4 +/- 90.6 vs. 183.5 +/- 68.8 g, p < 0.05) in patients with borderline hypertension compared with su bjects with normotension. In patients with established essential hyper tension, volume status of stroke volume and diastolic dimension return ed to normal values, whereas left ventricular mass increased further. Conclusions. We conclude that the early phase of hypertension is chara cterized by centripetal distribution of intravascular volume, leading to an increased preload to the left ventricle. This change in volume s tatus appears to be related to cardiac structural adaptation to an inc rease in arterial pressure.