Left ventricular vortex and intraventricular pressure difference in dogs under various loading conditions

Abstract

Restrictions on the conventional evaluation of diastolic function have been recognized, especially under various loading conditions. Recently, new noninvasive ventricular vortex indexes have been introduced and are expected to reflect the cardiac function. Physiologically, there is a hypothesis that the intraventricular pressure difference (IVPD) is related to the formation of vortexes. IVPD and vortex indexes were simultaneously measured, and the relationship between the two was investigated. To verify the possibility of diastolic vorticity as an index of diastolic relaxation, a correlation between diastolic vorticity and the load dependency of vorticity [time constant (τ)] was examined. Six healthy dogs were studied using transthoracic echocardiography, pressure, and a conductance catheter. Vorticity was analyzed using vector flow mapping (VFM). IVPD was determined using Euler’s equation with color M-mode Doppler images. Data were obtained at baseline, at balloon dilatation in the thoracic aorta to alter afterload, at hydroxyethyl starch infusion to alter preload, and at milrinone administration to alter ventricular relaxation. Peak vorticity at early diastole (E-Vor) and IVPD of the midventricle (MIVPD) decreased under pressure loading, were unchanged under volume loading, and increased during milrinone administration. In multivariate analysis, the independent predictors of τ were global longitudinal strain, strain rate at early diastole, and E-Vor. MIVPD was strongly correlated with E-Vor ( r = 0.84). VFM-derived peak E vorticity was strongly related to IVPD, especially MIVPD, under various loading conditions. Both of these novel indexes are promising as reliable indexes of ventricular relaxation, independent from preload. NEW & NOTEWORTHY We showed the close relationship of vortex and intraventricular pressure difference and showed that both of them can become new markers of the left ventricular relaxation property. Our present study creates a paradigm for future studies in the field of intraventircular flow physiology and clinical diastology.

The Utility of Intraventricular Pressure Gradient for Early Detection of Chemotherapy-Induced Subclinical Cardiac Dysfunction in Dogs

“…This suction force created by the pressure gradient from the left atrium to the LV apex is a major determinant of adequate filling in the early diastole during normal cardiac function [ 16 , 45 , 46 ]. The IVPG has been recognized as an index of diastolic function in early diastole [ 14 ]; however, in the present study, IVPG was decreased even though the diastolic function was preserved as indicated by the non-significant change in Tau and left ventricular end-diastolic pressure. At the beginning of relaxation, the energy stored in the LV wall during systole is released [ 47 ].…”

“…The mid to apical-IVPG, which is the pressure difference between mid and apical parts, represents a suction force that is reported to reflect the active relaxation of the LV during diastole. Besides, Tau, which is the most established index to describe left ventricular diastolic function that obtained invasively by catheterization, showed a negative correlation with total-, basal-, and mid-IVPD values in an experimental canine model under different loading conditions [ 14 ].…”

Changes in left ventricular blood flow during diastole due to differences in chamber size in healthy dogs

“…Vorticity can be obtained by intracardiac flow analysis using Vector Flow Mapping (VFM) or 4D-flow MRI 3,4 . Left ventricular vorticity during early diastolic phase reflect tau, which is the gold standard for measuring left ventricular relaxation property, independent from preload 5 . Another report showed that the vorticity related to clinical signs of diastolic dysfunction 5 .…”

“…Left ventricular vorticity during early diastolic phase reflect tau, which is the gold standard for measuring left ventricular relaxation property, independent from preload 5 . Another report showed that the vorticity related to clinical signs of diastolic dysfunction 5 . These reports suggested vorticity have a potential of to be a novel marker of diastolic function.…”

“…"Also, VFM is promising method that it enables evaluation" of cardiac function from a new viewpoint particularly in evaluating the energy efficiency 6,7 . Intraventricular pressure gradient (IVPG) can be measured by analyzing color M mode Doppler images is used to evaluate suction force of left ventricle 8 , which closely correlated to vorticity 5 . As is said in IVPG in a previous report, intracardiac blood flow can be affected by chamber size of the ventricle 9 .…”