Effect of hemodialysis on left ventricular function. Dissociation of changes in filling volume and in contractile
Insights
Hemodialysis improves left ventricular function by reducing fluid volume and enhancing contractility. Ultrafiltration alone primarily affects cardiac filling, while hemodialysis also boosts the heart's contractile state.
Area of Science:
- Cardiology
- Nephrology
- Physiology
Background:
- Previous studies on hemodialysis and left ventricular function did not differentiate between uremic toxin removal and volume changes.
- Understanding these distinct effects is crucial for managing cardiac health in dialysis patients.
Purpose of the Study:
- To elucidate the separate contributions of uremic toxin removal and volume changes to left ventricular (LV) function during hemodialysis.
- To analyze the impact of ultrafiltration versus hemodialysis on LV performance.
Main Methods:
- Serial echocardiography was used to assess LV function in five stable hemodialysis patients.
- Patients underwent three procedures: hemodialysis with volume loss, ultrafiltration only, and hemodialysis without volume loss.
- Cardiac filling volume was manipulated using head-down tilt and lower body negative pressure for comparison.
Main Results:
- Ultrafiltration led to decreased end-diastolic volume (EDV) and stroke volume (SV), consistent with a Frank-Starling mechanism.
- Hemodialysis with volume loss also reduced EDV and end-systolic volume (ESV), increasing ejection fraction (EF) and velocity of circumferential fiber shortening (VCF).
- Hemodialysis without volume loss decreased ESV and increased SV, EF, and VCF, indicating an enhanced contractile state independent of volume loss.
Conclusions:
- Ultrafiltration primarily impacts LV function via preload reduction (Frank-Starling effect).
- Hemodialysis, with or without volume loss, enhances left ventricular contractility.
- Regular hemodialysis improves LV function through a combination of reduced cardiac filling and increased myocardial contractility.
Abstract:
Prior studies of the effect of hemodialysis on left ventricular function have not distinguished between the removal of uremic toxins and the change in cardiac filling volume. To separate these effects, left ventricular function was examined by serial echocardiography in five stable hemodialysis patients before and after three different dialysis procedures: (a) hemodialysis with volume Loss, (b) ultrafiltration (volume loss only), and (c) hemodialysis without volume loss. The patients were similarly studied under control conditions and after increased (5 degrees of head-down tilt for 90 min) and decreased (lower body negative pressure) cardiac filling volume. After hemodialysis with volume loss, end-diastolic volume (EDV) decreased from 167 to 128 ml (P less than 0.001) and end-systolic volume (ESV) decreased from 97 to 51 ml (P less than 0.001) without a change in stroke volume (SV). Ejection fraction increased from 42 to 52% (P less than 0.001) and mean velocity of circumferential fiber shortening (VCF) increased from 0.61 to 1.04 circumferences (circ)/s (P less than 0.001). After ultrafiltration, EDV decreased from 167 ml to 124 ml (P less than 0.001) and SV from 73 ml to 39 ml (P less than 0.001), without significant changes in ESV or VCF. In contrast to the maneuvers in which volume loss occurred, after hemodialysis without volume loss ESV decreased from 95 to 66 ml (P less than 0.001) and SV increased from 74 ml to 97 ml (P less than 0.001) without changes in EDV. EF increased from 44 to 59% (P less than 0.001) and VCF increased from 0.64 to 1.26 circ/s (P less than 0.001). Ventricular function curves plotted from data obtained under conditions of altered cardiac filling volume before and after the three dialysis maneuvers demonstrate that ultrafiltration produced a pure Frank-Starling effect, while hemodialysis with or without volume loss produced a shift in the ventricular function curves, which demonstrated an increase in the contractile state of the left ventricle. The changes in left ventricular function produced by regular hemodialysis are the combined effects of a decrease in EDV and an increase in the contractile state of the left ventricle.
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