Left Ventricular Untwisting Rate by Speckle Tracking Echocardiography

Abstract

Background— Recent studies validated the measurement of left ventricular (LV) untwisting rate (UR) by speckle tracking echocardiography. A few reports suggest that it may provide additional noninvasive insight into LV diastolic function. Methods and Results— Simultaneous echocardiographic imaging and LV pressure measurements (7F Millar catheters) were performed in 8 adult dogs. Loading conditions were altered by caval occlusion, whereas lusitropic state was changed by dobutamine and esmolol infusion. Inferior vena cava occlusion at all experimental stages (baseline, dobutamine, esmolol) led to a significant decrease ( P ≤0.01) in LV end-systolic volume (ESV) and a significant increase in UR ( P =0.03). The best relation was observed between LV UR and ESV ( r =−0.8, P <0.001). The clinical study was conducted in 67 patients (age 57±17 years, 19 women) undergoing simultaneous right heart catheterization and echocardiographic imaging, with 20 healthy subjects as a control group. There were 34 patients with ejection fraction (EF) <50% (25±9%), and 33 patients with normal EF and diastolic dysfunction (64±7%). Patients with LV systolic dysfunction had a significantly lower UR (−55 ο/s) in comparison with the control group (−89 ο/s) and patients with normal EF (−104 ο/s, P <0.05), and the determinants of LV UR were twist, ESV, and τ (r 2 =0.83, P <0.001). In patients with diastolic dysfunction and normal EF, twist and ESV were the independent predictors (r 2 =0.71, P <0.001). Conclusions— LV UR is reduced in patients with depressed EF, but not in those with diastolic dysfunction and normal EF, and is primarily determined by twist and ESV.