Diastolic vortex ring derangements in ischemic cardiomyopathy left ventricles: a 4D Flow MRI study

Abstract

Abstract Funding Acknowledgements Type of funding sources: Private hospital(s). Main funding source(s): This work was supported by IRCCS Policlinico San Donato, a Clinical Research Hospital partially funded by the Italian Ministry of Health. Introduction Blood flowing into the left ventricle (LV) forms a 3D vortex ring starting from the free margin of mitral valve leaflets and encompassing the inflow jet. Vortex ring formation is presumed to store part of the kinetic energy of the entering jet and help directing blood flow towards the aorta [1]. Changes in vortex formation are associated to altered endocardial wall motion and LV chamber remodeling, as in case of ischemic cardiomyopathy (ICM). 4D Flow MRI is currently the unique volumetric imaging technique to assess in vivo changes of diastolic vortex ring. Purpose To characterize changes in LV diastolic vortex ring and associated energetics in a cohort of ICM patients (n = 12) vs. controls (n = 12) with comparable age. Methods 4D Flow MRI data were acquired for ICM patients presenting with anterior myocardial infarction and in healthy controls. The diastolic vortex ring was assessed at peak E-wave and at peak A-wave through the λ2 method [2]. Geometrical features of the vortex ring, e.g., circularity index (CI) and vortex orientation (α), were extracted (Figure 1). Kinetic energy (KE), rate of viscous energy loss (EL), vorticity and volume were computed for each vortex ring core; the ratios with the respective quantities computed for the entire LV were derived. Results At peak E-wave, the vortex ring was less circular (p = 0.017) and formed a smaller α with the mitral valve plane (p = 0.024) in ICM patients as compared to controls. At peak A-wave, the vortex ring core remained less circular (p = 0.027) in ICM patients, while vortex orientation remained comparable between the two groups. KE ratio, EL ratio, vorticity ratio and volume ratio significantly decreased for ICM patients at both E-peak and A-peak (Table 1). Conclusions Though ICM is primarily addressed and investigated as a systolic dysfunction, diastolic function can be deranged too, as highlighted by altered diastolic vortex ring shape and energetics.