Interaction between left ventricular wall motion and intraventricular flow propagation in acute and chronic ischemia

Abstract

The combination of tissue Doppler imaging and high framerate acquisition of two-dimensional color flow makes it possible to study the interaction between LV wall motion and intraventricular flow propagation. The aim of this study was to examine in a clinical model the impact that acute myocardial ischemia and prior myocardial infarct might have on LV flow patterns and to explain the underlying mechanisms from the tissue Doppler data. LV flow propagation and tissue velocities during early diastole were studied in 18 healthy individuals, 17 patients with prior anterior myocardial infarct, and 16 patients before and during percutaneous coronary intervention (PCI) of the left anterior descending artery. Normal individuals had intraventricular flow propagation toward the apex during isovolumic relaxation. During this early diastolic time phase, myocardial velocities measured at mid-and apical septal segment were directed away from the apex. Before PCI, patients without myocardial infarction had similar findings as in normal individuals. In contrast, each patient with either prior myocardial infarction or PCI-induced acute ischemia had flow propagation opposite to normal individuals, and tissue velocities reversed toward the apex during early diastole. Reversal of early diastolic LV flow propagation in acute and chronic anterior myocardial ischemia reflects postsystolic shortening in the dyskinetic apical and septal myocardial segments.

Intraventricular Isovolumic Relaxation Flow Patterns Studied by Using Vector Flow Mapping

“…IRF has been described as an apically directed, basally directed, or bidirectional flow occurring in the isovolumic relaxation (IVR) period. An intraventricular pressure gradient caused by inhomogeneous LV segmental early relaxation due to asynchronous ventricular activation–inactivation is now considered to be the underlying mechanism for the development of IRF . In normal subjects, the earlier activation–inactivation in the apical half of the LV may bring about the segmental early relaxation.…”

“…Recently, the events during the IVR period have been scrutinized as heralding changes in LV function. The duration and velocity of IRF have been shown to be useful in the noninvasive estimation of LV systolic and early diastolic performance …”

Unsupervised dealiasing and denoising of color-Doppler data

“…2): in the classical red-blue colormap, colorencoded velocities wrap around so that color information turns from red to blue or vice versa. Recent quantitative tools with potentially high clinical interest rely upon the velocity field measured by color Doppler (Yotti et al, 2005;Arigovindan et al, 2007;Edvardsen et al, 2005). Recovering aliased velocities is a sine qua non for these techniques to afford reliable information.…”

Interaction between the septum and the left (right) ventricular free wall in order to evaluate the effects on coronary blood flow: numerical simulation

“…Many patients with advanced heart failure (HF) exhibit significant intra-ventricular or inter-ventricular conduction delays (IVCD) that disturb the synchronous beating of the ventricles so that they pump less efficiently (Edvardsen et al 2005;Kalogeropoulos et al 2008). Ventricular dyssynchrony can produce a number of deleterious effects on cardiac function such as reduced diastolic filling time, weakened contractility, protracted mitral regurgitation and post-systolic regional contraction.…”