Non-Doppler two dimensional strain imaging for evaluation of coronary artery disease.

Over the recent years, strain echocardiography has emerged as a quantitative technique for the evaluation of global and segmental cardiac function. Strain is a measure of deformation, expressed as a percent change in a segment's length compared to its predeformation length. Strain rate (SR) is the local rate of deformation or strain per unit time. Recently non-Doppler two dimensional strain imaging has been developed. This technique is based on tracking ultrasonic speckles from the two dimensional echocardiographic images. These speckles are followed over a number of successive frames, and myocardial velocity is calculated by measuring frame-to-frame changes. This technique is independent of the Doppler angle of incidence and allows measurement of several vectors of strain within myocardial tissue. Non-Doppler strain is a powerful tool, enabling detection of subtle abnormalities in myocardial function. Current evidence shows that non-Doppler strain imaging may allow identification of the early changes that occur with ischemic insult to the myocardium. It may also provide a tool for identification of scarred, non-viable myocardium, with similar accuracy to that of cardiac MRI. Non-Doppler strain imaging is likely to become a standard tool in the evaluation of patients with ischemic heart disease.