Currently available technology for echocardiographic assessment of left ventricular function

Abstract

New ultrasound technology is mainly represented by tissue Doppler (TD), which allows the quantitative analysis of myocardial function and includes two modalies: pulsed-wave TD and color TD. Strain rate imaging (SRI) is an implementation of color TD. Pulsed-wave TD, performed and analyzed in real time, instantaneously measures myocardial velocities. Color TD, performed offline on digitally stored images, allows the quantification of mean myocardial velocities. The advantage of color TD compared with pulsed TD is the ability to simultaneously analyze multiple myocardial segments. The limit of both these methodologies consists of the myocardial velocity dependence by the base–apex myocardial gradient. SRI measures the rate and percentage of myocardial wall deformation. From digitally recorded color TD cine loops containing velocity data from the entire myocardium, SRI can be derived from regional Doppler velocity gradients. Strain rate is relatively load dependent, and, therefore, can be considered a strong index of myocardial contractility. Due to these favorable characteristics, SRI may potentially overcome the limitations of color TD, discriminating between active and merely passive wall motion. A novel technique is the implemention of 2D SRI, which is not angle dependent, and therefore potentially more feasible and reliable.