Flow imaging, within the numerous limitations of the specific method employed here, may enable us to uncover a relationship between the quality of intraventricular vortex dynamics and cardiac function. LV flow represents an integral outcome of the tissue contraction/relaxation process whose dynamic features (local and short lasting) may not be easily detectable in terms of tissue displacement. Hemodynamic forces are known to participate in morphogenesis in embryonic hearts; therefore, they may also be one concurring factor during the pathological development of the grown heart [
1]. The vortical hydrodynamic forces and their cytomechanical consequences by mechanosensing and mechanotransduction can radically affect ventricular remodeling with epigenetic nexus [
4,
5]. The results of the only multi-center trial [
6] in this field, led to the conclusion that no single echocardiographic measure of dyssynchrony may be recommended to improve patient selection for CRT due to the extreme variability of the collected data, and the applicability of dyssynchrony optimization in a “real-world” clinical setting is questionable. RT3D-TTE has shown an acceptable ability to assess left ventricular dyssynchrony, pre-CRT, with SDI [
7], and to help guide lead placement that is concordant with the site of latest mechanical activation demonstrated with displays that are highly intuitive and desirable from an electrophysiologist’s perspective. However, high-quality images at high volume rate by RT3D-TTE are not always obtainable for patients with dilated cardiomyopathy, and the temporal resolution could hamper the analysis of small-scale variations of ventricular dyssynchrony and could thus influence the identification of appropriate pacing setting during acute echocardiographic optimization of left pacing vector. Moreover, current evidence does not strongly support the performance of atrioventricular (AV) and ventriculo-ventricular (VV) optimization routinely in all patients receiving CRT [
8]. The analysis of flow dynamics inside the LV can provide new information about LV systolic and diastolic function through the analytical representation of the distribution of intraventricular pressure gradients; the assessment of morphological and energetic characteristics of fluid dynamics, both at baseline pre-implantation and after biventricular pacing, is potentially combinable with other parameters of echocardiographic methods that quantify LV systolic performance and residual systolic dyssynchrony respectively, to correct suboptimal device settings. In fact, it was previously suggested that fluid dynamics represents a sort of coupling between systole and diastole without a sharp separation between them [
9]; this is because flow properties at one instant depend on the combination of mechanical events during previous time. The echo-PIV technique may be useful for elucidating the favorable effects of CRT on intraventricular fluid dynamics and it could be used to identify appropriate pacing setting during acute echocardiographic optimization of left pacing vector [
2], with no relevant changes in electrical activation on EKG in the different LV pacing setting. This positive experience could be further tested in patients with narrow or intermediate QRS duration who may be expected to benefit from CRT, using echo-PIV analysis for measuring the extraordinary complexity of flow–wall relationship throughout the cardiac cycle.