The role of contrast enhancement in echocardiographic assessment of left ventricular function

With or without contrast, echocardiographic evaluation of left ventricular (LV) function is qualitative, subjective, and experience dependent, because it is mostly based on visual interpretation of gray-scale 2-dimensional images or, at best, relies on tedious and time-consuming manual tracing of the endocardial boundaries. Adequate endocardial visualization is essential for accurate interpretation of regional wall thickening abnormalities, which constitute the diagnostic hallmark of coronary artery disease, and for reproducible assessment of LV ejection fraction. Studies performed in the last decade have estimated the number of patients with suboptimal endocardial delineation by fundamental imaging at 30%. These studies have highlighted the problem of variable image quality as a major limitation of transthoracic echocardiography because failure to adequately visualize a segment, either at rest or during stress, may compromise the ability of this technique to identify areas of dysfunctional myocardium. Several remedies based on different technologic and methodologic approaches have been tested over the years with variable success. In this review we discuss the most recent techniques that have had a positive impact on endocardial visualization, as well as the potential benefits of these approaches.