Key result
Acute venesection with saline replacement reduced exercise augmentation index (from 24% to 17%; P=0.001) and improved LV systolic function in patients with altered blood rheology.
Why the study?
Does venesection with volume replacement improve ventricular-vascular response to exercise in patients with altered blood rheology?
Does venesection with volume replacement improve ventricular-vascular response to exercise in patients with altered blood rheology?
p-value: p=0.001
An acute reduction in plasma viscosity via venesection improves left ventricular systolic function and reduces central blood pressure during light exercise in patients with altered blood rheology.
Hypothesis-generating for venesection in altered rheology; prospective randomized trials needed before clinical consideration.
Blood (or plasma) rheology is related to cardiovascular risk. Mechanisms of this association are unclear but may be partially related to impaired left ventricular (LV) function and increased central blood pressure (BP) during light activity. This study aimed to test these hypotheses. Twenty patients (14 men; aged 61+/-12 years) with polycythemia rubra vera (n=16) or hemochromatosis (n=4) were studied at rest and during exercise at approximately 50% of maximal heart rate before and after venesection (500 mL; volume replaced with saline) to elicit an acute decrease in plasma viscosity at stable BP. Controls (n=20) underwent the same protocol with 25-mL venesection. Central BP and augmentation index were determined by tonometry. Resting LV systolic (peak longitudinal systolic strain rate and strain) and diastolic functions were determined by tissue-Doppler echocardiography. Venesection with blood volume replacement decreased viscosity (1.46+/-0.10 to 1.41+/-0.11 centipoise), protein, and hemoglobin (P<0.05 for all) and increased strain rate and strain (P<0.001 for both) in patients but not in controls (P>0.10 for all). There was no change in LV diastolic function (P>0.12 for all). Exercise augmentation index in patients was reduced after venesection (24+/-12% to 17+/-9%; P=0.001) despite no significant change in other BP variables. Hemodynamics (resting or exercise) were not significantly changed in controls. Exercise central systolic BP correlated with triglycerides (r=0.59; P<0.001). However, neither exercise hemodynamic changes nor LV functional changes correlated with any biochemical changes after venesection (P>0.05). We conclude that an acute change in blood rheology improves ventricular-vascular interaction by enhanced LV systolic function and reduced light-exercise central BP.
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Sharman et al. (2009) studied Polycythemia rubra vera or hemochromatosis (n=40). Venesection with saline volume replacement vs. 25-mL venesection was evaluated on Exercise augmentation index (p=0.001). Acute venesection with saline replacement reduced exercise augmentation index (from 24% to 17%; P=0.001) and improved LV systolic function in patients with altered blood rheology.