Exercise tolerance of heart transplant patients is often limited. Central and peripheral factors have been proposed to explain such exercise limitation but, to date, the leading factors remain to be determined. We examined how a short-term endurance exercise training programme may improve exercise capacity after heart transplantation, and whether atrial natriuretic peptide (ANP) release may contribute to the beneficial effects of exercise training by minimizing ischaemia and/or cardiac and circulatory congestion through its vasodilatation and haemoconcentration properties. Seven heart transplant recipients performed a square-wave endurance exercise test before and after 6 weeks of supervised training, while monitoring haemodynamic parameters, ANP and catecholamine concentrations. After training, the maximal tolerated power and the total mechanical work load increased from 130.4 (SEM 6.5) to 150.0 (SEM 6.0) W (P < 0.05) and from 2.05 (SEM 0.1) to 3.58 (SEM 0.14) kJ.kg-1 (P < 0.001). Resting heart rate decreased from 100.0 (SEM 3.4) to 92.4 (SEM 3.5) beats.min-1 (P < 0.05) but resting and exercise induced increases in cardiac output, stroke volume, right atrial, pulmonary capillary wedge, systemic and pulmonary artery pressures were not significantly changed by training. Exercise-induced decrease of systemic vascular resistance was similar before and after training. After training arterio-venous differences in oxygen content were similar but maximal lactate concentrations decreased from 6.20 (SEM 0.55) to 4.88 (SEM 0.6) mmol.l-1 (P < 0.05) during exercise. Similarly, maximal exercise noradrenaline concentration tended to decrease from 2060 (SEM 327) to 1168 (SEM 227) pg.ml-1. A significant correlation was observed between lactate and catecholamines concentrations. The ANP concentration at rest and the exercise-induced ANP concentration did not change throughout the experiment [104.8 (SEM 13.1) pg.ml-1 vs 116.0 (SEM 13.5) pg.ml-1 and 200.0 (SEM 23.0) pg.ml-1 vs 206.5 (SEM 25.9) pg.ml-1, respectively]. The results of this study suggested that the significant improvement in exercise capacity observed after this short-term endurance training period may have arisen mainly through peripheral mechanisms, associated with the possible decrease in plasma catecholamine concentrations and reversal of muscle deconditioning and/or prednisone-induced myopathy.

In 228 patients, fetal blood pH, pCO2 and lactic acid were measured in two distinguishable parts of the second stage of labor. The 'first' part begins at full cervical dilatation and ends when the mother starts her first voluntary bearing down efforts. In our study, the fetal acid-base status did not change in this part, regardless of a late developing hypoxia. In contrast, higher levels of lactic acid and pCO2 and lower pH values were observed in the 'final' part of the second stage, indicating increasing acidosis. In this 'final' part, the fetuses with clinical signs of distress, as defined by an ominous Apgar score at birth, showed quicker and larger acid-base shifts than did the normal fetuses. Thus the two parts of the second stage of labor actually differ in their potential to stimulate fetal acidosis. Since such fetal acidosis may develop especially during the 'final' part of labor, we have concluded that special particular attention should be devoted to this part.

Brain natriuretic peptide (BNP), a recently discovered cardiac hormone, is secreted mainly by the cardiac ventricles and has potent diuretic, natriuretic, and vasorelaxant properties. Circulating BNP levels are increased in pa-tients with heart failure in proportion to the severity of the disease and may have important compensatory renal, cardiovascular, and endocrinologic actions. Cardiac transplantation, a recognized treatment for end-stage heart failure, normalizes the neuroendocrine balance, but atrial natriuretic peptide and BNP levels remain elevated in heart-transplant recipients. 1 Contrasting with the numerous studies focused on atrial natriuretic peptide in heart transplantation 2 and despite the greater potential beneficial effects of BNP, few data are available concerning the BNP level response to cardiac transplantation. 3, 4 Method and results. Plasma BNP levels were determined by radioimmunoassay with kits from Peninsula Laboratories (Belmont, Calif.) after extraction by Sep Pak C18 cartridges (Waters Chromatography, Milford, Mass.) in 25 patients just before and daily during the first week after either heart transplantation (n ϭ 15) or coronary

The purpose of this study was to investigate whether maternogenic fetal acidosis can occur at the time of labor and delivery and to evaluate the extent of the possible maternal contribution to fetal acidosis. We have therefore determined fetal and maternal lactate concentrations and acid-base status under various conditions in 589 women at the end of gestation and during labor. The results show that metabolic acidosis develops in all fetuses because of increased production of lactic acidosis is primarily of fetal origin: 1) the umbilical arteriovenous lactate differences were positive and large in steady-state conditions as well as in depressed newborns; 2) the conditions that could produce a net transfer of lactate from the mother to the fetus, namely a positive maternofetal gradient of lactate and proton, were rarely observed; and 3) the correlation between fetal and maternal lactate levels was very weak, with regression coefficients decreasing from near steady-state conditions to acute stress conditions, indicating that the increase in lactate in the fetus and mother occurs independently. This correlation indicates also that increased maternal lactate production under conditions of labor and delivery can make a contribution by affecting the rate of net transfer from fetus to mother. This is possible in approximately 6% of the fetuses.

This first report of the effect of Albunex injected intravenously on pulmonary artery pressures in humans demonstrates that this contrast agent appears to be safe. The significant left ventricular opacification obtained in a majority of patients without an important increase in attenuation supports the use of the higher dose of the contrast agent.