Altered Diastolic Flow Patterns and Kinetic Energy in Subtle Left Ventricular Remodeling and Dysfunction Detected by 4D Flow MRI

Abstract

Aims4D flow magnetic resonance imaging (MRI) allows quantitative assessment of left ventricular (LV) function according to characteristics of the dynamic flow in the chamber. Marked abnormalities in flow components’ volume and kinetic energy (KE) have previously been demonstrated in moderately dilated and depressed LV’s compared to healthy subjects. We hypothesized that these 4D flow-based measures would detect even subtle LV dysfunction and remodeling.Methods and ResultsWe acquired 4D flow and morphological MRI data from 26 patients with chronic ischemic heart disease with New York Heart Association (NYHA) class I and II and with no to mild LV systolic dysfunction and remodeling, and from 10 healthy controls. A previously validated method was used to separate the LV end-diastolic volume (LVEDV) into functional components: direct flow, which passes directly to ejection, and non-ejecting flow, which remains in the LV for at least 1 cycle. The direct flow and non-ejecting flow proportions of end-diastolic volume and KE were assessed. The proportions of direct flow volume and KE fell with increasing LVEDV-index (LVEDVI) and LVESV-index (LVESVI) (direct flow volume r = -0.64 and r = -0.74, both P<0.001; direct flow KE r = -0.48, P = 0.013, and r = -0.56, P = 0.003). The proportions of non-ejecting flow volume and KE rose with increasing LVEDVI and LVESVI (non-ejecting flow volume: r = 0.67 and r = 0.76, both P<0.001; non-ejecting flow KE: r = 0.53, P = 0.005 and r = 0.52, P = 0.006). The proportion of direct flow volume correlated moderately to LVEF (r = 0.68, P < 0.001) and was higher in a sub-group of patients with LVEDVI >74 ml/m2 compared to patients with LVEDVI <74 ml/m2 and controls (both P<0.05).ConclusionDirect flow volume and KE proportions diminish with increased LV volumes, while non-ejecting flow proportions increase. A decrease in direct flow volume and KE at end-diastole proposes that alterations in these novel 4D flow-specific markers may detect LV dysfunction even in subtle or subclinical LV remodeling.

Scan–rescan reproducibility of diastolic left ventricular kinetic energy, viscous energy loss and vorticity assessment using 4D flow MRI: analysis in healthy subjects

“…Multiple 4D flow MRI studies showed that patients with LV dysfunction present altered flow patterns through the LV with impaired preservation of inflow KE to the end of diastole and altered KE-time curves (the amount of KE inside the LV during each time step over the total cardiac cycle) [4,6,7,21], even in patients with normal to mild LV remodeling and normal to mildly depressed LV systolic function [7]. These KE changes in the LV could be a valuable diagnostic marker to evaluate diastolic function and might be useful for early detection of deteriorating ventricular function [1, 4-7, 21, 22], which could reduce patient morbidity and mortality [23].…”

“…4D flow MRI has recently emerged as a novel tool for in vivo quantification of intracardiac flow energetics, associated energy losses and vortical flow patterns by means of kinetic energy (KE) [4][5][6][7], viscous energy loss (EL) [1] and vorticity [8,9]. KE is the energy contained in the flow of the bloodstream due to motion and EL is the KE that is irreversibly lost due to viscosity-induced frictional forces within the blood flow [1].…”

“…In acquired heart disease, remodelling occurs which can lead to alterations in intracardiac hemodynamics [4]. Alteration in intraventricular KE derived from 4D flow MRI has been used to assess left ventricular (LV) and right ventricular (RV) (dys)function in patients with different stages of heart failure (HF) [4][5][6][7]. This is also the case in various congenital heart diseases.…”

Assessment of Ventricular Function in Normal and Failing Hearts Using 4D Flow CMR

“…In myopathic LVs, reduced volume and pre-systolic KE of the Direct Flow has been demonstrated compared to normal LVs (62,91). The inflowing Direct Flow proceeds deeper into the LV chamber and interacts more with blood already residing in the LV.…”

“…This inefficient flow of blood through the heart may influence diastolic wall stress, and thus, contribute to further myocardial remodeling. Furthermore, the altered diastolic flow routes and impaired preservation of pre-systolic KE have been demonstrated in compensated heart failure patients with mildly remodeled LVs compared to normal LVs despite similar LV stroke volume (91).…”