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CLINICAL RESEARCH: CARDIAC IMAGING

A Novel Feature-Tracking Echocardiographic Method for the Quantitation of Regional Myocardial Function

Validation in an Animal Model of Ischemia-Reperfusion

Methodist DeBakey Heart Center Echocardiography Laboratory and Baylor College of Medicine, Division of Cardiology, Houston, Texas.

Manuscript received May 14, 2007; revised manuscript received September 25, 2007, accepted October 15, 2007.

^_* Reprint requests and correspondence: Dr. William A. Zoghbi, Methodist DeBakey Cardiovascular Imaging Center, 6550 Fannin Street SM677, Houston, Texas 77030. (Email: wzoghbi{at}tmhs.org).

This study has been presented as an abstract at the annual scientific sessions of the American Heart Association, Chicago, Illinois, November 15, 2006.

Objectives: The aim of this study was to validate a novel, angle-independent, feature-tracking method for the echocardiographic quantitation of regional function.

Background: A new echocardiographic method, Velocity Vector Imaging (VVI) (syngo Velocity Vector Imaging technology, Siemens Medical Solutions, Ultrasound Division, Mountain View, California), has been introduced, based on feature tracking—incorporating speckle and endocardial border tracking, that allows the quantitation of endocardial strain, strain rate (SR), and velocity.

Methods: Seven dogs were studied during baseline, and various interventions causing alterations in regional function: dobutamine, 5-min coronary occlusion with reperfusion up to 1 h, followed by dobutamine and esmolol infusions. Echocardiographic images were acquired from short- and long-axis views of the left ventricle. Segment-length sonomicrometry crystals were used as the reference method.

Results: Changes in systolic strain in ischemic segments were tracked well with VVI during the different states of regional function. There was a good correlation between circumferential and longitudinal systolic strain by VVI and sonomicrometry (r = 0.88 and r = 0.83, respectively, p < 0.001). Strain measurements in the nonischemic basal segments also demonstrated a significant correlation between the 2 methods (r = 0.65, p < 0.001). Similarly, a significant relation was observed for circumferential and longitudinal SR between the 2 methods (r = 0.94, p < 0.001 and r = 0.90, p < 0.001, respectively). The endocardial velocity relation to changes in strain by sonomicrometry was weaker owing to significant cardiac translation.

Conclusions: Velocity Vector Imaging, a new feature-tracking method, can accurately assess regional myocardial function at the endocardial level and is a promising clinical tool for the simultaneous quantification of regional and global myocardial function.

Abbreviations and Acronyms   LAD = left anterior descending coronary artery   LV = left ventricle/ventricular   SR = strain rate   VVI = Velocity Vector Imaging   2D = 2-dimensional