To determine the effect of increasing intraabdominal pressure on left ventricular (LV) systolic function in patients undergoing continuous ambulatory peritoneal dialysis (CAPD), we studied 15 patients who had been on CAPD for at least 2 months. The study protocol included measurement of echocardiographic LV internal dimensions in diastole and systole, LV wall thickness and mass, LV ejection time, the mean velocity of circumferential fiber shortening (mean Vcf), heart rate, BP, and intraabdominal pressure. Measurements were obtained at baseline (OL) and following intraperitoneal infusion of 1-L increments of dialysate solution (up to 4 L) in both the recumbent and standing positions. Significant differences in LV systolic function resulting from intraperitoneal infusion of dialysate were confined to the subgroup with increased LV wall thickness (n = 8). In this subgroup, mean Vcf decreased progressively from 0.99 +/- 0.18 circumferences/second at baseline to 0.88 +/- 0.16 circumferences/second at 1 L (P = NS), to 0.86 +/- 0.16 circumferences/second at 2 L (P = NS), to 0.66 +/- 0.18 circumferences/second at 3 L (P less than 0.005), and to 0.60 +/- 0.14 circumferences/second at 4 L (P less than 0.005) in recumbent position. Measurements obtained in the standing position paralleled those observed during recumbency. These changes were accompanied by a significant decrease in the mean LV internal dimension in diastole and a significant increase in intraabdominal pressure, but no significant change in the mean LV internal dimensions in systole, mean heart rate, or mean systolic or diastolic BP.(ABSTRACT TRUNCATED AT 250 WORDS)