Vorticity is a novel index that reflects diastolic function of left ventricle. The size of the ventricle can influence the ventricular diastolic blood flow. We evaluated effect of ventricular size on diastolic function and diastolic intracardiac blood flow using a particular species of dogs, which has a wide range of body size. Vector flow mapping was used for evaluation of intracardiac blood flow, and intraventricular pressure gradient (IVPG) was used for evaluation of diastolic function. 58 dogs weighing 1.3-42.3 kg were included in this study. Vorticity was found to be inversely proportional to the length of the ventricular chamber. Intraventricular pressure difference was positively correlated with the length of the left ventricle, whereas IVPG was not. This study showed that the vorticity is influenced by the size of the left ventricle independently of other factors. To evaluate the hemodynamic state of each individual appropriately by using vorticity and IVPD, ventricular size should be taken into account especially in the field of veterinary medicine and human pediatric and adolescent cardiology.www.nature.com/scientificreports www.nature.com/scientificreports/ vorticity and EL. A stepwise method was used for selection of the variables, choosing the variables which minimized Akaike's information criterion. ResultsStudy population. The number of cases was 58. The mean weight was 8.65 (1.3-42.3, SD 6.93) kg. The length of the left ventricle was 34.0 (21.9-49.0, SD 7.3) mm on average. The mean heart rate was 117.6 (66.0-Characteristics of the canine heart with various size. The mean value of the short axis inner diameter of the left ventricle (LVIDd) was SD 7.36) mm. The sphericity index (SI) of the left ventricle was 0.75 (0.51-1.0, SD 0.12). The relationship between short and long axis diameter was shown in Fig. 1. LVL was linearly correlated with LVIDd (R = 0.78, p < 0.01). Statistical correlation was not found between LVL and SI.Conventional indexes of diastolic property (E vel, e′, E/A, E/e′) were not statistically correlated with LVL.Scientific RepoRtS | (2020) 10:1106 | https://doi.

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.

Introduction Intraventricular pressure gradient is regarded as a non-invasive indicator of diastolic function. Salvianolic acid B (Sal-B), a traditional Asian medicine, revealed its usefulness in myocardial infarction models; however, the hemodynamic effect of salvianolic acid B is still unknown. The present study aimed to investigate the intraventricular pressure gradient changes during the development of left ventricular hypertrophy with or without salvianolic acid B and a beta-blocker. Methods In total, 48 rats were divided into four groups; Sham, Non-treatment, salvianolic acid B, and Carvedilol. Aortic coarctation-induced left ventricular hypertrophy was done in three groups and the treatment was started from the third to the sixth week. Blood pressure, conventional echocardiography, and color M-mode echocardiography for measurement of intraventricular pressure gradient were carried out for six consecutive weeks. Results At 4.5 weeks, the LV mass was elevated in the coarctation groups but the blood pressure was significantly lower in salvianolic acid B and Carvedilol groups ( P < 0.05). In the Non-treatment group, the total intraventricular pressure gradient was increased at 4.5 and 6 weeks (2.60 and 2.65, respectively). Meanwhile, the basal intraventricular pressure gradient was elevated at 3 and 6 weeks (1.67 and 1.75) compared with the Sham group. Salvianolic acid B and Carvedilol significantly reduced the basal intraventricular pressure gradient at six weeks compared with the Non-treatment group (1.52 and 1.51 vs 1.75, respectively). Conclusions Salvianolic acid B and Carvedilol promote cardiac function by decreasing the elevated basal intraventricular pressure gradient. The current preclinical results revealed the efficacy of salvianolic acid B as a potential therapy for left ventricular hypertrophy because of the non-blood pressure lowering effect.

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.

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