Effect of Loading Changes on the Intraventricular Pressure Measured by Color M-Mode Echocardiography in Rats

Abstract

Evaluation of diastolic function is a pivotal challenge due to limitations of the conventional echocardiography, especially when the heart rate is rapid as in rats. Currently, by using color M-mode echocardiography (CMME), intraventricular pressure difference (IVPD) and intraventricular pressure gradient (IVPG) in early diastole can be generated and are available as echocardiographic indices. These indices are expected to be useful for the early diagnosis of heart failure (HF), especially diastolic dysfunction. There have not been any studies demonstrating changes in IVPD and IVPG in response to changes in loading conditions in rats. Therefore, the present study aims to evaluate CMME-derived IVPD and IVPG changes in rats under various loading conditions. Twenty rats were included, divided into two groups for two different experiments, and underwent jugular vein catheterization under inhalational anesthetics. Conventional echocardiography, CMME, and 2D speckle tracking echocardiography were measured at the baseline (BL), after intravenous infusion of milrinone (MIL, n = 10), and after the infusion of hydroxyethyl starch (HES, n = 10). Left ventricular IVPD and IVPG were calculated from color M-mode images and categorized into total, basal, mid-to-apical, mid, and apical parts, and the percentage of the corresponding part was calculated. In comparison to the BL, the ejection fraction, mid-to-apical IVPG, mid IVPG, and apical IVPD were significantly increased after MIL administration (p < 0.05); meanwhile, the end-diastolic volume, E-wave velocity, total IVPD, and basal IVPD were significantly increased with the administration of HES (p < 0.05). The increase in mid-to-apical IVPD, mid IVPD, and apical IVPD indicated increased relaxation. A significant increase in basal IVPD reflected volume overloading by HES. CMME-derived IVPD and IVPG are useful tools for the evaluation of various loading conditions in rats. The approach used in this study provides a model for continuous data acquisition in chronic cardiac disease models without drug testing.

Evaluation of Changes in the Cardiac Function before and after Transcatheter Edge-to-Edge Mitral Valve Repair in Healthy Dogs: Conventional and Novel Echocardiography

“…In the present report, the postoperative E wave was higher than the preoperative measurement, likely caused by the decreased mitral orifice area following the device placement. The E wave is sometimes used for the estimation of atrial pressure; however, the E wave can be affected by multiple factors, including preload, diastolic function, and others [ 18 , 27 ].…”

“…Recent echocardiographic approaches such as two-dimensional speckle tracking echocardiography (2D-STE) and intraventricular pressure gradients (IVPG) calculated from color M-mode echocardiography create a breakthrough in cardiology research for the early diagnosis of cardiac dysfunctions, as compared with other traditional methods [ 16 , 17 , 18 ]. In the present report, the echocardiographic changes were evaluated using conventional echocardiography, 2D-STE and CMME, before and weekly after the implantation of the TEER in two clinically normal dogs.…”

Changes in Cardiac Function During the Development of Uremic Cardiomyopathy and the Effect of Salvianolic Acid B Administration in a Rat Model

“…Combined with the fact that E wave velocity, E′, and E/E′ also showed no differences between the groups, it is easily concluded that LA pressure was not elevated in the UC group. The usefulness of 2DSTE and IVPG for assessing cardiac function was confirmed in rats before ( 12 , 13 , 34 ). Myocardium dysfunction detected by STE combined with the fact that intracardiac flow was not disturbed in UC to provide us with an interesting conclusion: subtotal nephrectomy induced UC rat model could be used for cardiovascular drug selection.…”

“…Intraventricular pressure gradients (IVPG), the pressure gradients inside the ventricle that draw blood from the left atrium (LA) to the LV during diastole, have been strongly correlated with left atrial (LA) pressure and active relaxation ( 10 ). Our previous research proved that IVPG could be used as a serial cardiac function evaluation tool in rodent and dog models ( 11 – 13 ).…”

Color M-Mode Echocardiography for Non-Invasive Assessment of the Intraventricular Pressure in Dogs Before and After Ductus Arteriosus Occlusion: A Retrospective Study

“…Current cardiovascular research focuses on the development of non-invasive diagnostics for diastolic dysfunction. This is because heart failure with preserved ejection fraction (HFpEF) is known to account for half of the patients diagnosed with end-stage heart failure, and the accurate diagnostic methods are challenging and have not yet been established ( 17 ). Evaluation of diastolic function using conventional echocardiography is limited as the measurements are affected by the heart rate and arrhythmias.…”