Clinical and hemodynamic determinants of left ventricular dimensions

This study was designed to quantitate the influence of 20 clinical, hemodynamic, and volume determinants of left ventricular (LV) structure. Systemic hemodynamics, intravascular volume, and LV echocardiographic measurements were collected in a heterogeneous population of 171 patients. Stepwise multiple-regression analysis indicated that body weight and body-surface area were the most powerful determinants of LV chamber size, wall thickness, and muscle mass. Age, a pressure independent determinant of myocardial mass, had no influence on chamber size or LV function. Arterial pressure correlated best with the relative wall thickness and chamber volume. Intravascular volume was a major discriminator for chamber volume, LV mass, and velocity of circumferential fiber shortening. It is concluded that body weight, arterial pressure, intravascular volume, and age are each independent determinants of the LV dimension. Systolic pressure most closely correlated with relative wall thickness and thereby is the best predictor of degree of concentric LV hypertrophy

Low-dose cyclophosphamide enhances helper-to-non-helper ratios

This study was conducted to analyze the effect of different doses of cyclophosphamide (CY) on the lymphocyte populations in the rat. Monoclonal antibodies against rat determinants were used: W3/13 (T lymphocytes), W3/25 (T helper), OX-8 (non-helper), and OX-33 (B lymphocytes). Blood samples were collected on days 0, 3, 7, and 14 from four groups of F-344 Fisher rats (n = 4): three that received 25, 50, or 75 mg/kg of CY and a control group. The duration and severity of lymphocyte depletion were dose-related and were evident for both helper and non-helper cells (p less than 0.02). The helper-to-non-helper ratio increased for the group that received 25 mg/kg when compared with control and other groups, but was only significantly changed when compared with the 75 mg/kg group (p = 0.004). This effect was transitory and was only seen on day 3. The control and the 25 mg/kg groups gained weight; the other two groups lost weight (p less than 0.05). Lower doses of CY were associated with a transitory immunostimulatory effect and no morbidity when compared with higher doses

Essential hypertension in the elderly: Haemodynamics, intravascular volume, plasma renin activity, and circulating catecholamine levels

In an attempt to dissociate the cardiovascular adaptations to high blood pressure from those of ageing, 30 patients with established essential hypertension aged over 65 years were matched for mean arterial pressure, race, sex, height, and weight with 30 patients younger than 42 years. Cardiac output, heart rate, stroke volume, intravascular volume, renal blood flow, and plasma renin activity were significantly lower in the elderly, whereas total peripheral (and renal vascular) resistance, left ventricular posterior wall and septal thickness, and left ventricular mass were higher. Intravascular volume correlated inversely with total peripheral resistance in both groups and in all patients. Pathophysiological findings of essential hypertension in the elderly are characterised by a hypertrophied heart of the concentric type with a low cardiac output resulting from a smaller stroke volume and a slower heart rate. Renal blood flow is disproportionally reduced and total peripheral and renal vascular resistance elevated