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.
Highlights
Heart failure (HF) is a major health problem with a prevalence of more than 23 million people worldwide caused by both diastolic and systolic dysfunctions [1,2]
hydroxyethyl starch (HES) significantly increased LVIDd (6.97 vs. 7.66 mm, p < 0.05), end-diastolic volume (EDV) (0.43 vs. 0.65 mL, p < 0.01), Stroke volume (SV) (0.62 vs. 0.86 mL, p < 0.01), E-wave (74.6 vs. 122 cm/s, p < 0.01), and E/e of the septal (14.8 vs. 21.1, p < 0.01) and lateral (13.4 vs. 16.1, p < 0.01) annuli compared with the BL
We studied the response of intraventricular pressure difference (IVPD) and intraventricular pressure gradient (IVPG) indices to pharmacologically induced alteration in the loading conditions in rats
Summary
Heart failure (HF) is a major health problem with a prevalence of more than 23 million people worldwide caused by both diastolic and systolic dysfunctions [1,2]. The IVPD can be estimated from CMME by calculating Euler equations; the sucking force in the ventricle can be determined noninvasively [6]. This allows calculation of the IVPD between any two points in the ventricle; the LV can be divided into several segments for detailed evaluation. The length of the LV, from the mitral valve to the apex, is divided into basal, mid, and apical parts, and each part has its corresponding IVPD and IVPG indices and a defined role in the diagnosis of cardiac dysfunction. Mid-to-apical IVPG was found to reflect the active relaxation of the LV during diastole, whereas the apical IVPG plays the main role in actively sucking the blood into the ventricle [13,14]
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