Intraventricular vortex properties in nonischemic dilated cardiomyopathy

Abstract

Vortices may have a role in optimizing the mechanical efficiency and blood mixing of the left ventricle (LV). We aimed to characterize the size, position, circulation, and kinetic energy (KE) of LV main vortex cores in patients with nonischemic dilated cardiomyopathy (NIDCM) and analyze their physiological correlates. We used digital processing of color-Doppler images to study flow evolution in 61 patients with NIDCM and 61 age-matched control subjects. Vortex features showed a characteristic biphasic temporal course during diastole. Because late filling contributed significantly to flow entrainment, vortex KE reached its maximum at the time of the peak A wave, storing 26 ± 20% of total KE delivered by inflow (range: 1-74%). Patients with NIDCM showed larger and stronger vortices than control subjects (circulation: 0.008 ± 0.007 vs. 0.006 ± 0.005 m(2)/s, respectively, P = 0.02; KE: 7 ± 8 vs. 5 ± 5 mJ/m, P = 0.04), even when corrected for LV size. This helped confining the filling jet in the dilated ventricle. The vortex Reynolds number was also higher in the NIDCM group. By multivariate analysis, vortex KE was related to the KE generated by inflow and to chamber short-axis diameter. In 21 patients studied head to head, Doppler measurements of circulation and KE closely correlated with phase-contract magnetic resonance values (intraclass correlation coefficient = 0.82 and 0.76, respectively). Thus, the biphasic nature of filling determines normal vortex physiology. Vortex formation is exaggerated in patients with NIDCM due to chamber remodeling, and enlarged vortices are helpful for ameliorating convective pressure losses and facilitating transport. These findings can be accurately studied using ultrasound.

A clinical method for mapping and quantifying blood stasis in the left ventricle

“…The normal LV flow pattern has been reported to recycle the blood volume inside the left ventricle every 2–3 beats (Figure 2A) (Bolger et al 2007, Eriksson et al 2010, Hendabadi et al 2013, Watanabe et al 2008). However, blood transport is significantly altered in patients with NIDCM by the large swirling flow patterns that are typical of this condition (Figure 2B–C) (Bermejo et al 2014, Hendabadi et al 2013). In these patients, blood is trapped inside long-lasting vortices and undergoes rotation throughout most of the cardiac cycle (see supplementary movie 1).…”

“…The LV myocardial wall was segmented, and its longitudinal and transversal strain were measured from the apical long-axis B-mode sequences to delineate the endocardial boundary (EchoPac v.110.1.2, General Electric Healthcare). We reconstructed the 2D+t flow field inside the LV using 2D echo color Doppler velocimetry (echo-CDV), as previously described and validated in vitro (Garcia et al 2010) and in vivo (Bermejo et al 2014). The 2D flow velocity fields together with the LV segmentation were used to integrate the unit-forced transport equation and to calculate the spatio-temporal evolution of blood residence time inside the LV (see below).…”

“…In the healthy heart, these phenomena result in a small residual volume with no associated blood stasis. However, intraventricular flow patterns are significantly altered by disease (Bermejo et al 2014, Eriksson et al 2013, Hong et al 2008, Rodriguez Munoz et al 2013). How these disturbed flow dynamics may lead to increased blood stasis is only beginning to be understood (Eriksson et al 2013, Hendabadi et al 2013).…”

Ultrasound Vector Flow Imaging: I: Sequential Systems

“…VFM is readily available in Hitachi scanners and has been tested in several clinical situations [114], [115], [116]. It has also been assessed in patients with echocardiographic data extracted from GE (General Electric Healthcare) Vivid scanners [117], [118], [119], [120]. It appears from these clinical studies that the analysis of the diastolic vortex dynamics could improve diastology.…”

“…In the normal heart, a large part of the left ventricular blood volume is actually involved in the vortex formation. Recent in-vivo observations suggest that the vortices that form during left ventricular filling have specific geometries and locations, which could be determinant factors of the diastolic function [42], [165], [114], [118], [166]. Intraventricular vortex flow imaging is becoming increasingly popular in the clinical literature and it is anticipated that accurate measures of the intracardiac vortex hemodynamics might play a key role in the assessment of the cardiac function (Fig.…”