Nebivolol improved stroke volume, ejection fraction and left ventricular end-diastolic pressure, not through a measurable reduction in afterload or a lusitropic effect, but by improving systolic contractile performance.
Ventilation with positive end-expiratory pressure (PEEP) is associated with reduced cardiac output, but the mechanisms involved are controversial. Possible explanations include increased intrathoracic pressure, reflex changes in myocardial inotropism, pulmonary vascular obstruction and abnormal ventricular interaction. Three types of conscious canine preparations were developed to examine simultaneously each of these factors during ventilation with PEEP. In addition, similar measurements were obtained in patients after cardiac surgical procedures and compared with the results of animal experiments. The primary cause of reduced cardiac output during PEEP appeared to be a diminished end-diastolic volume of the left ventricle, and this appeared to be the result of elevated intrathoracic pressure and increased impedance to blood flow through the lungs. Abnormal interventricular septal shifting and reflex autonomic alterations did not appear to be significant in the normal cardiovascular system. These data provide insight into the cardiac effects of PEEP and emphasize the importance of simultaneous quantification of biventricular performance when assessing cardiopulmonary function.
The efficacy of nifedipine (20 to 40 mg twice daily) and captopril (25 to 50 mg twice daily) was assessed during a 12-week single-blind randomized trial in 41 moderately hypertensive black patients (mean 24-h diastolic blood pressure [BP] > or = 90 mm Hg and < 115 mm Hg). Nifedipine and captopril were administered as monotherapy in increasing dosage while a diuretic was added after 8 weeks in patients who failed to reach the target BP (24-h mean diastolic BP < 90 mm Hg) on monotherapy. After 8 weeks of monotherapy, the mean 24-h ambulatory BP was reduced from 156 +/- 12/101 +/- 5 to 128 +/- 11/84 +/- 7 mm Hg (P < .0001) in the nifedipine group while it remained essentially unchanged (156 +/- 15/101 +/- 7 to 158 +/- 17/102 +/- 9) in the captopril group. Left ventricular (LV) mass index was also reduced significantly (P < .05) in the nifedipine group, while cardiac index and fractional shortening changed marginally. The addition of diuretic in the captopril group (16/21 patients) resulted in a significant fall in BP to 123 +/- 11/81 +/- 7. Only 2/20 patients in the nifedipine group required the addition of diuretic. The overall incidence of side effects was similar with both treatments but the addition of diuretic in the captopril group was followed by adverse changes in serum sodium (P < .01), urea (P < .05), and creatinine (P < .01) levels.(ABSTRACT TRUNCATED AT 250 WORDS)
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