Changes in electrical activation modify the orientation of left ventricular flow momentum: novel observations using echocardiographic particle image velocimetry

Abstract

Changes in electrical activation alter the orientation of blood flow momentum. The long-term CRT outcome correlates with the degree of re-alignment of haemodynamic forces. These preliminary results suggest that flow orientation could be used for optimizing the biventricular pacing setting. However, larger prospective studies are needed to confirm this hypothesis.

Clinical assessment of intraventricular blood transport in patients undergoing cardiac resynchronization therapy

“…direct flow), (2) increasing the amount of kinetic energy that is transferred from incoming blood to ejected blood, and (3) aligning the motion of the ejected blood with the left ventricular outflow tract. Furthermore, our results and the emerging literature imply that CRT favors the generation of coherent intraventricular pressure gradients that accelerate blood in the direction of the LV outflow tract [31]. Finally, the impact of different transport patterns on intraventricular flow mixing and prevention of blood stasis needs to be addressed [37].…”

“…It is important to note that M is a vector that not only indicates the magnitude of the acceleration of each fluid volume, but also its direction. The orientation of the whole ventricle’s M with respect with the ventricular long axis has been recently shown to correlate with long-term outcome in patients undergoing CRT [31]. We calculated the ratio η K = K DF /K LV at aortic valve opening in all the patients to determine if CRT changes contributed to efficiently focusing the inflow kinetic energy into the volume of fluid that was ejected during systole.…”

“…When compared to baseline conduction, biventricular stimulation seems to improve organization of intraventricular flow, suggesting that intraventricular flow analysis is a useful tool to understand the effects of resynchronization on heart mechanics [30]. Remarkably, changes in electrical activation have been shown to modify the net orientation of the forces acting on blood inside the LV, which has been associated with improved long-term outcome in patients undergoing CRT [31]. These findings suggest that flow imaging may be a suitable tool for optimizing this therapy.…”

Significant increase of flow kinetic energy in “nonresponders” patients to cardiac resynchronization therapy

“…This study presents preliminary data to support the role of Echo‐PIV for quantifying the effects of CRT on vortex formation. Goliash et al . demonstrated that in patients with chronically implanted CRT devices, the acute interruption of CTR alters LV filling characteristics, while the reactivation reversed these characteristics instantly, suggesting an important favorable role played by CRT on optimization of LV diastolic filling.…”

Intracardiac flow analysis in cardiac resynchronization therapy: A new challenge?

“…Pedrizzetti et al, using the same echo‐PIV technique, studied the LV hemodynamic forces in CRT responders and nonresponders. In CRT responders presenting a longitudinal alignment of the LV hemodynamic forces, pacing switch‐off determined loss of alignment of intraventricular forces and development of transversal components, despite cardiac contractility and synchrony parameters did not show measurable changes (Figure ).…”