II Doppler tessutale nella valutazione della funzione miocardica durante ecocardiografia da stress

Recently, stress echocardiography has emerged as a valuable tool for the diagnosis and evaluation of coronary artery disease, but its interpretation still remains subjective, relying on image quality and reader's experience. These problems could be overcome by quantitative analysis of wall motion. Tissue Doppler provides quantitative information on regional myocardial systolic and diastolic velocities that can be displayed either in spectral mode or color coded, reflecting the peak velocity increment induced by exercise or dobutamine administration. Pulsed wave tissue Doppler allows to measure regional instantaneous myocardial velocities with high temporal resolution and has been shown valuable for detecting stress-induced changes of both myocardial systolic and diastolic function. This method may also identify myocardial viability by measuring increase in systolic peak velocity at low-dose of dobutamine in dysfunctional myocardial segments. Color coded tissue Doppler resolves mean velocities with higher spatial resolution, and post-processing analysis of digital acquired images has been shown feasible and reproducible. Myocardial velocity gradient is a more sensitive parameter compared to the simple measurement of the peak endocardial systolic velocity for evaluating myocardial ischemia during dobutamine echocardiography. From the raw data, it is also possible to measure strain and strain rate. These new parameters have the potential to differentiate between wall motion and contractility, with obvious implications when applied to stress echocardiography. In conclusion, tissue Doppler is able to quantify regional myocardial function. After a large scale validation, this technique will be incorporated with stress echocardiography in clinical practice.