Evaluation of diastolic function is a pivotal challenge due to limitations of the conventionalechocardiography, especially when the heart rate is rapid as in rats. Currently, by using color M-mode echocardiography (CMME), intraventricular pressure difference (IVPD) and intraventricularpressure gradient (IVPG) in early diastole can be generated and are available as echocardiographicindices. These indices are expected to be useful for the early diagnosis of heart failure (HF), especiallydiastolic dysfunction. There have not been any studies demonstrating changes in IVPD and IVPGin response to changes in loading conditions in rats. Therefore, the present study aims to evaluateCMME-derived IVPD and IVPG changes in rats under various loading conditions. Twenty ratswere included, divided into two groups for two different experiments, and underwent jugular veincatheterization under inhalational anesthetics. Conventional echocardiography, CMME, and 2Dspeckle tracking echocardiography were measured at the baseline (BL), after intravenous infusion ofmilrinone (MIL,n= 10), and after the infusion of hydroxyethyl starch (HES,n= 10). Left ventricularIVPD 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. Incomparison to the BL, the ejection fraction, mid-to-apical IVPG, mid IVPG, and apical IVPD weresignificantly 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 ofHES (p< 0.05). The increase in mid-to-apical IVPD, mid IVPD, and apical IVPD indicated increasedrelaxation. A significant increase in basal IVPD reflected volume overloading by HES. CMME-derivedIVPD and IVPG are useful tools for the evaluation of various loading conditions in rats. The approachused in this study provides a model for continuous data acquisition in chronic cardiac disease modelswithout drug testing. |
