New noninvasive method for assessment of left ventricular rotation - Speckle tracking echocardiography

Background: Left ventricular (LV) torsion is due to oppositely directed apical and basal rotation and has been proposed as a sensitive marker of LV function. In the present study, we introduce and validate speckle tracking echocardiography (STE) as a method for assessment of LV rotation and torsion. Methods and Results: Apical and basal rotation by STE was measured from short-axis images by automatic frame-to-frame tracking of gray-scale speckle patterns. Rotation was calculated as the average angular displacement of 9 regions relative to the center of a best-fit circle through the same regions. As reference methods we used sonomicrometry in anesthetized dogs during baseline, dobutamine infusion, and apical ischemia, and magnetic resonance imaging (MRI) tagging in healthy humans. In dogs, the mean peak apical rotation was -3.7 +/- 1.2 degrees (+/- SD) and -4.1 +/- 1.2 degrees, and basal rotation was 1.9 +/- 1.5 degrees and 2.0 +/- 1.2 degrees by sonomicrometry and STE, respectively. Rotations by both methods increased (P < 0.001) during dobutamine infusion. Apical rotation by both methods decreased during left anterior descending coronary artery occlusion (P < 0.007), whereas basal rotation was unchanged. In healthy humans, apical rotation was -11.6 +/- 3.8 degrees and -10.9 +/- 3.3 degrees, and basal rotation was 4.8 +/- 1.7 degrees and 4.6 +/- 1.3 degrees by MRI tagging and STE, respectively. Torsion measurement by STE showed good correlation and agreement with sonomicrometry (r = 0.94, P < 0.001) and MRI (r = 0.85, P < 0.001). Conclusions: The present study demonstrates that regional LV rotation and torsion can be measured accurately by STE, suggesting a new echocardiographic approach for quantification of LV systolic function.