The dual effects of hemodialysis on cardiac function assessed by pulsed Doppler echocardiography.

To assess the effect of hemodialysis on cardiac function, a change of preload due to water removal was considered. In order to keep the preload constant during hemodialysis, extracorporeal ultrafiltration was induced before hemodialysis (step 1), and then hemodialysis without water removal was achieved (step 2). Cardiac performance in 8 patients was evaluated before and at the end of each step using pulsed doppler echocardiography. Step 1: Ultrafiltration was 1350 +/- 410 ml and hematocrit increased significantly. Left ventricular end-diastolic dimension (LVDd) decreased from 40.3 +/- 4.2 (mean +/- standard deviation) mm to 36.1 +/- 4.6 mm (p less than 0.005) and aortic peak flow velocity (PFV) also decreased from 59.9 +/- 16.0 cm/s to 49.0 +/- 11.0 cm/s (p less than 0.005). Step 2: In contrast, after hemodialysis without water removal, the mean velocity of circumferential fiber shortening (mVcf) increased from 1.36 +/- 0.26 circ/s to 1.86 +/- 0.36 circ/s (p less than 0.005). PFV and average acceleration (Aa) increased from 49.0 +/- 11.0 cm/s to 63.8 +/- 11.4 cm/s (p +/- 0.001) and from 750 +/- 220 cm/s/s to 1270 +/- 280 cm/s/s (p less than 0.001), respectively. During this step, serum potassium and osmolality decreased significantly. In conclusion, hemodialysis improves cardiac function under constant preload condition and this is due to the direct effects of hemodialysis by the correction of electrolytes and osmolar components such as uremic toxin.