Aims: Left ventricular torsion (LVtor) measures the rotational deformation of the myocardium and plays an important role in LV contraction and filling. Two-dimensional (2D) speckle tracking echocardiography (STE) has been validated as a reproducible non-invasive technique to assess LVtor. LVtor is altered in many disease states, but the effects of loading conditions on LVtor have not been established. The aim of this study was to evaluate the effect of load alteration on LVtor as assessed by 2D STE.
Methods and results: Simultaneous echocardiographic imaging and high-fidelity left ventricular pressure measurements were performed in 17 patients with a normal ejection fraction (mean 61 ± 10%) before and after infusion of nitroprusside. All measurements were obtained simultaneously at baseline and then during a steady-state infusion of nitroprusside. Nitroprusside caused a decrease in LV systolic pressure, a decrease in effective arterial elastance (Ea), and a decrease in LV filling pressures. There was a faster rate of LV relaxation with nitroprusside with a decrease in tau from 53 ± 18 to 33 ± 14 ms (P < 0.005). Peak LVtor, apical rotation, twisting rate (TR), and untwisting rate (UTR) each increased after nitroprusside infusion when compared with baseline (P < 0.001). A correlation was found between the change in LV filling pressure and the change of LVtor (r = -0.54, P = 0.02), TR (r = -0.50, P = 0.04), and UTR (r = 0.54, P = 0.02). There was a significant correlation between the change of LVtor and change of Ea (r = -0.66, P < 0.05).
Conclusion: LV torsion, TRs, and UTRs are all enhanced in the setting of drug-induced vasodilation, indicating substantial load dependence. These findings must be taken into consideration when evaluating LVtor in disease states.