Volume depletion provided by blood donation alters twist mechanics of the heart: Preload dependency of left ventricular torsion

Abstract

Objectives: The crucial role of twisting motion on both left ventricular (LV) contraction and relaxation has been clearly identified. However, the reports studying the association between LV torsion and loading conditions have revealed conflicting outcomes. Previously normal saline infusion was shown to increase LV rotation. Our aim was to test this phenomenon after volume depletion in healthy volunteer blood donors. Design: A total of 26 healthy male volunteers were included in the study. LV end-diastolic and end-systolic diameter, LV ejection fraction, LV diastolic parameters, LV apical and basal rotation and peak systolic LV torsion were measured by speckle-tracking echocardiography before and after 450 mL blood donation. Results: Blood donation led to a significant decrease in end-diastolic LV internal diameter (48.7 +/- 0.4 versus 46.4 +/- 0.4mm; p<0.001) and cardiac output (6.2 +/- 1.0 versus 5.1 +/- 0.7 L/min; p<0.001). There was a significant decrease in the magnitude of peak systolic apical rotation (4.4 +/- 1.9 degrees versus 2.9 +/- 1.5 degrees; p<0.001) but no change in basal rotation (2.6 +/- 1.4 degrees versus 2.7 +/- 1.6 degrees; p=0.81). Peak systolic LV Torsion decreased after blood donation (6.9 +/- 1.9 degrees versus 5.7 +/- 2.1 degrees; p=0.028). Conclusions: LV apical rotation and peak systolic LV torsion seem to be preload dependent. Preload reduction provided by 450-mL blood donation decreased LV torsion in healthy male volunteers. Volume dynamics should be taken into account in the evaluation of LV torsion.