Influence of Left Ventricular Preload Reduction by Hemodialysis on the Doppler-Derived Left Ventricular Filling Profile

The influence of left ventricular preload alterations on left ventricular diastolic filling was examined by performing M mode and pulsed Doppler echocardiography in 18 patients with chronic renal failure both before and after hemodialysis. Hemodialysis caused an average 3.2-liter volume loss, but blood pressure and heart rate did not change significantly. Hemodialysis diminished the left atrial dimension (35 ± 5 to 31 ± 5 mm; p < 0.001) and the left ventricular end-diastolic dimension (55 ± 6 to 50 ± 5 mm; p < 0.01), indicating that it reduced left ventricular preload. Although hemodialysis decreased both the peak velocity during rapid filling (R; 54 ± 10 to 36 ± 11 cm/s; p < 0.001) and the peak velocity during atrial contraction (A; 68 ± 9 to 58 ± 10 cm/s; p < 0.001), it increased the A/R ratio (1.29 ± 0.24 to 1.71 ± 0.41; p < 0.001) substantially. Reduction of uremic toxins and/or correction of electrolyte imbalances might be expected to improve both left ventricular relaxation and systolic function. However, following left ventricular preload reduction after hemodialysis, the Doppler-derived transmitral flow velocity profile mimicked previously reported patterns of impaired diastolic function. These results indicate that the atrial contribution to ventricular filling was more effective afterwards than before hemodialysis and that under depressed left ventricular diastolic function, the atrial contribution decreased as preload increased further. This decrease in the A/R ratio with an elevation of left ventricular preload could be termed ‘pseudonormalization’ of the transmitral flow velocity profile. To differentiate this ‘pseudonormalized’ profile from a truly normal one, left ventricular preload must be considered.