Quantitative Assessment of Short Axis Wall Motion Using Myocardial Strain Rate Imaging

Abstract

Although left ventricular wall motion has been usually assessed with four-point scale (1 = normal; 2 = hypokinesis; 3 = akinesis; 4 = dyskinesis) based on the visual assessment, this method is only qualitative and subjective. Recently, a new echocardiographic system that enables calculation of myocardial strain rate based on tissue Doppler information has been developed. We investigated whether myocardial strain rate could quantify regional myocardial contraction in 17 patients with and without wall motion abnormalities including 6 patients undergoing dobutamine stress echocardiography. Left ventricular short-axis wall motion was assessed with standard two-dimensional echocardiography at basal, mid-ventricular, and apical levels. The same levels were imaged with tissue Doppler method to determine regional myocardial strain rate. Sixty-four segments were judged normokinesis, 53 segments hypokinesis, and 18 segments akinesis at rest; 16 segments were judged normokinesis and 6 segments hypokinesis at stress. No segments characterized dyskinesis. Strain rates of normokinetic, hypokinetic, and akinetic wall segments at rest were significantly different each other (-2.0 +/- 0.6 for normokinesis,-0.6 +/- 0.5 for hypokinesis,P < 0.0001 vs. normokinesis, and-0.008 +/- 0.3 for akinesis, P < 0.0001 vs. normokinesis and hypokinesis). Further, strain rates well reflected the change in wall motion induced by dobutamine challenge: strain rates in the 15 segments revealing augmented wall motion changed from -2.0 +/- 0.7 to -4.7 +/- 1.7 (1/sec) (P < 0.0001) and those in the 7 segments revealing deteriorated or unchanged wall motion changed from -2.1 +/- 1.0 to -1.7 +/- 0.8 (1/sec) (P < 0.05). In conclusion, strain rate agreed well with assessed wall motion. Strain rate imaging may be a new powerful tool to quantify regional wall contraction.

Assessment of Regional Myocardial Function in Patients with Dilated Cardiomyopathy by Velocity Vector Imaging

“…SRI derived from DTI had been used more effectively in the study of cardiac function 1,2 . Mirsky and Parmley 3 were the first to introduce the concept of S and SR as measures of myocardial mechanical properties.…”

Velocity Vector Imaging in Assessing the Regional Systolic Function of Patients with Post Myocardial Infarction

“…SRI based on DTI had been proved more efficient than the conventional wall score analysis in assessing the myocardial ischemia 3,4 . As this methodology is based on Doppler technology, it is one‐dimensional.…”

Quantitative Assessment of Wall Motion Using Myocardial Strain

“…Myocardial strain rate by Doppler echocardiography is theoretically uninfluenced by effects of the whole heart translation and tethering from the adjacent myocardium because it utilizes the velocity difference between neighboring two points. We and others have shown the feasibility of strain rate to quantify wall motion [21,22]. However, as is well known, strain rate signal has significant noise, which hampers the routine use of this method clinically.…”