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Dive into the research topics where Tomoya Morita is active.

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Featured researches published by Tomoya Morita.


Journal of Veterinary Internal Medicine | 2014

Prognostic Value of Left Atrial Function in Dogs with Chronic Mitral Valvular Heart Disease

Kensuke Nakamura; Tatsuyuki Osuga; Keitaro Morishita; S. Suzuki; Tomoya Morita; Nozomu Yokoyama; Hiroshi Ohta; Masahiro Yamasaki; Mitsuyoshi Takiguchi

Background A strong correlation between left atrial (LA) dysfunction and the severity of cardiac disease has been described in human patients with various cardiac diseases. The role of LA dysfunction in dogs with chronic mitral valvular heart disease (CMVHD) has not been addressed. Objectives To investigate the correlation between LA function and the prognosis of dogs with CMVHD. Animals Thirty‐eight client‐owned dogs with CMVHD. Methods Prospective clinical cohort study. Dogs were divided into 2 groups (survivors and nonsurvivors) based on the onset of cardiac‐related death within 1 year. Physical examination and echocardiographic variables were compared between the groups. For the assessment of the comparative accuracy in identifying patients with cardiac‐related death, receiver operating characteristic (ROC) curves and multivariate logistic analysis were used. Results The highest accuracy was obtained for the LA active fractional area change (LA‐FAC act), with an area under the ROC curve (AUC) of 0.95, followed by the left atrial to aortic root ratio (LA/Ao), with an AUC of 0.94; peak early diastolic mitral inflow velocity (E), with an AUC of 0.85; and LA total fractional area change (LA‐FAC total), with an AUC of 0.85. In the multivariate logistic regression analysis, LA‐FAC act emerged as the only independent correlate of cardiac‐related death within 1 year (odds ratio = 1.401, P = .002). Conclusions and Clinical Importance Regarding both the size and function, the LA has a strong correlation with the prognosis of dogs with CMVHD. The most significant independent predictor of mortality in this study was LA‐FAC act.


Journal of Veterinary Internal Medicine | 2016

Prognostic Value of Right Ventricular Tei Index in Dogs with Myxomatous Mitral Valvular Heart Disease

Kensuke Nakamura; Tomoya Morita; Tatsuyuki Osuga; Keitaro Morishita; Noboru Sasaki; Hiroshi Ohta; Mitsuyoshi Takiguchi

Background The right ventricular (RV) Tei index (TX) has a significant correlation with the severity of pulmonary hypertension. However, the role of RV dysfunction in dogs with myxomatous mitral valvular heart disease (MMVD) has not been addressed. Objectives To investigate the correlation between right ventricular Tei‐index (RVTX) and the prognosis for dogs with MMVD. Animals Thirty client‐owned dogs with MMVD. Methods Clinical cohort study. Dogs were divided into two groups on the basis of the onset of cardiac‐related death within 1 year of the first echocardiographic examination. Physical examination and echocardiographic variables were compared between the groups. Receiver operating characteristic (ROC) curves and multivariate logistic analysis were used to assess the comparative accuracy when identifying dogs with cardiac‐related death. Results The highest accuracy was obtained for RVTX with an area under the ROC curve (AUC) of 0.95 (95% confidence interval [CI] 0.81–0.99) followed by the left atrial to aortic root ratio with an AUC of 0.91 (95% CI 0.74–0.98), peak early diastolic mitral inflow velocity with an AUC of 0.84 (95% CI 0.64–0.94), and Doppler estimates of systolic pulmonary artery pressure with an AUC of 0.84 (95% CI 0.61–0.95). According to the multivariate logistic regression analysis, RVTX was the only independent correlate of cardiac‐related death within 1 year. Conclusions and Clinical Importance Right ventricular Tei‐index has a strong correlation with the prognosis for dogs with MMVD. The most significant independent predictor of death was RVTX in this study.


American Journal of Veterinary Research | 2016

Repeatability and reproducibility of right ventricular Tei index valves derived from three echocardiographic methods for evaluation of cardiac function in dogs

Tomoya Morita; Kensuke Nakamura; Tatsuyuki Osuga; Sue Yee Lim; Nozomu Yokoyama; Keitaro Morishita; Hiroshi Ohta; Mitsuyoshi Takiguchi

OBJECTIVE To evaluate repeatability and reproducibility of right ventricular Tei index (RTX) values derived from dual pulsed-wave Doppler, conventional pulsed-wave Doppler, and tissue Doppler echocardiography and to investigate relationships and repeatability among the 3 methods in healthy dogs. ANIMALS 6 healthy adult Beagles. PROCEDURE Echocardiography was performed on each dog on different days for 2 weeks (3 times/d) by 2 echocardiographers. Intraobserver within- and between-day and interobserver coefficients of variation (CVs) and intraclass correlation coefficients (ICCs) for RTXs derived from dual pulse-waved Doppler (RTXDPD), conventional pulsed-wave Doppler (RTXPD), and tissue Doppler (RTXTD) methods were determined. Degrees of agreement among RTX values derived from the 3 methods were assessed by modified Bland-Altman analysis. RESULTS Least squares mean (95% confidence interval) RTXtd was 0.50 (0.46 to 0.54), which was significantly higher than that for RTXDPD (0.27 [0.23 to 0.31]) and RTXPD (0.25 [0.21 to 0.29]). Agreement between RTXDPD and RTXPD was good (bias [mean difference], 0.04 [95% confidence interval, -0.03 to 0.10]). The RTXdpd had high within-day (CV, 6.1; ICC, 0.77) and interobserver (CV, 3.5; ICC, 0.83) repeatability, but between-day repeatability was not high. The RTXtd had high within-day repeatability (CV, 6.0; ICC, 0.80), but between-day and interobserver repeatability were not high. Within-day, between-day, and interobserver repeatability of RTXPD were not high. CONCLUSIONS AND CLINICAL RELEVANCE RTXdpd measurement was a repeatable and reproducible method of cardiac evaluation in healthy dogs. The RTXTD values were significantly higher than the RTXDPD and RTXPD values; therefore, RTX values derived from different echocardiographic methods should be interpreted with caution.


Journal of Veterinary Internal Medicine | 2015

Vitamin D Status in Different Stages of Disease Severity in Dogs with Chronic Valvular Heart Disease.

Tatsuyuki Osuga; Kensuke Nakamura; Tomoya Morita; Sue Yee Lim; Khoirun Nisa; Nozomu Yokoyama; Noboru Sasaki; Keitaro Morishita; Hiroshi Ohta; Mitsuyoshi Takiguchi

Background In humans with heart disease, vitamin D deficiency is associated with disease progression and a poor prognosis. A recent study showed that serum 25‐hydroxyvitamin D [25(OH)D] concentration, the hallmark of vitamin D status, was lower in dogs with heart failure than in normal dogs, and a low concentration was associated with poor outcome in dogs with heart failure. Objectives To elucidate the vitamin D status of dogs with chronic valvular heart disease (CVHD) at different stages of disease severity. Animals Forty‐three client‐owned dogs with CVHD. Methods In this cross‐sectional study, dogs were divided into 3 groups (14 dogs in Stage B1, 17 dogs in Stage B2, and 12 dogs in Stage C/D) according to ACVIM guidelines. Dogs underwent clinical examination including echocardiography. Serum 25(OH)D concentrations were measured in each dog. Results Serum 25(OH)D concentration was significantly lower in Stage B2 (median, 33.2 nmol/L; range, 4.9–171.7 nmol/L) and C/D (13.1 nmol/L; 4.9–58.1 nmol/L) than in Stage B1 (52.5 nmol/L; 33.5–178.0 nmol/L) and was not significantly different between Stage B2 and Stage C/D. Among clinical variables, there were significant negative correlations between 25(OH)D concentration and both left atrial‐to‐aortic root ratio and left ventricular end‐diastolic diameter normalized for body weight. Conclusions and Clinical Importance These results indicate that vitamin D status is associated with the degree of cardiac remodeling, and the serum 25(OH)D concentration begins to decrease before the onset of heart failure in dogs with CVHD.


Journal of Veterinary Internal Medicine | 2017

Left Atrial Strain at Different Stages of Myxomatous Mitral Valve Disease in Dogs

Kensuke Nakamura; S. Kawamoto; Tatsuyuki Osuga; Tomoya Morita; Noboru Sasaki; Keitaro Morishita; Hiroshi Ohta; Mitsuyoshi Takiguchi

Background Decreased function of the left atrium (LA) is a useful prognostic indicator in dogs with myxomatous mitral valve disease (MMVD). In humans, LA strain is a novel severity indicator of mitral regurgitation, but its clinical utility in dogs has not been confirmed. Objectives To examine whether LA strain as evaluated with speckle‐tracking echocardiography is associated with MMVD stage in dogs. Animals Fifty‐two client‐owned dogs with MMVD. Methods Cross‐sectional study. Dogs were classified as stage B1, B2, C, or D, according to the American College of Veterinary Internal Medicine consensus. Physical examination findings and echocardiographic variables were compared among the groups. To assess the comparative accuracy of echocardiographic variables in identifying dogs with the presence or history congestive heart failure (CHF), receiver operating characteristic curves and multivariate logistic analysis were used. Results There were no significant differences in parameters of LA strain between B1 and B2 groups. However, LA longitudinal strain during atrial contraction (εA) (median, 19.1%; interquartile range, 15.3–24.3% in B1, 19.6%; 14.1–21.4% in B2, 6.2%; 3.18–11.2% in C/D) and during ventricular systole (εS) (32.7%; 28.9–39.2% in B1, 35.6%; 31.7–41.9% in B2, 23.6%; 16.9–26.1% in C/D) were significantly lower in stages C/D than in stages B1 and B2. In multivariate logistic regression analysis, εA and peak early diastolic mitral inflow velocity were identified as independent indicators of stage C/D. Conclusions and Clinical Importance εA was the best predictor of the presence or history of CHF. Further studies are needed to determine the clinical implications of these findings for treatment decisions and prognosis determination.


Journal of Veterinary Cardiology | 2017

The repeatability and characteristics of right ventricular longitudinal strain imaging by speckle-tracking echocardiography in healthy dogs

Tomoya Morita; Kensuke Nakamura; Tatsuyuki Osuga; Nozomu Yokoyama; N. Khoirun; Keitaro Morishita; Noboru Sasaki; Hiroshi Ohta; Mitsuyoshi Takiguchi

INTRODUCTION To assess the repeatability and characteristics of echocardiographic indices of the right ventricular (RV) function derived from speckle-tracking echocardiography. ANIMALS Fourteen laboratory Beagles and 103 privately owned dogs without cardiac disease were involved in this study. MATERIALS AND METHODS Right ventricular longitudinal strain, strain rate, and a strain-related index for assessing RV dyssynchrony derived from speckle-tracking echocardiography were obtained by two different observers using five Beagles. Within-day, between-day, and interobserver coefficients of variation and the intraclass correlation coefficient of speckle-tracking echocardiography indices were determined. Both speckle-tracking echocardiography and conventional indices of RV function, including the peak velocity of systolic tricuspid annular motion, tricuspid annulus plane systolic excursion, fractional area change, and the Tei index, were obtained from 14 Beagles and 103 privately owned dogs. Relationships between echocardiographic indices and the body weight, heart rate, age, and sex were estimated by regression analysis. RESULTS Speckle-tracking echocardiographic indices showed good within-day repeatability, between-day and interobserver repeatability were moderate to good. In large dogs, RV longitudinal strain, strain rate, and fractional area change were significantly decreased, while the index of RV dyssynchrony, systolic tricuspid annular motion, tricuspid annulus plane systolic excursion, and the Tei index were increased. All speckle-tracking and conventional echocardiographic indices were correlated with the body weight. DISCUSSION AND CONCLUSIONS The speckle-tracking echocardiography indices were highly repeatable and body weight affected speckle-tracking echocardiography indices in dogs. Further studies are needed to apply speckle-tracking echocardiography indices in dogs with cardiac disease.


American Journal of Veterinary Research | 2016

Effects of experimental cardiac volume loading on left atrial phasic function in healthy dogs

Tatsuyuki Osuga; Kensuke Nakamura; Tomoya Morita; Khoirun Nisa; Nozomu Yokoyama; Noboru Sasaki; Keitaro Morishita; Hiroshi Ohta; Mitsuyoshi Takiguchi

OBJECTIVE To elucidate the relationship between acute volume overload and left atrial phasic function in healthy dogs. ANIMALS 6 healthy Beagles. PROCEDURES Dogs were anesthetized. A Swan-Ganz catheter was placed to measure mean pulmonary capillary wedge pressure (PCWP). Cardiac preload was increased by IV infusion with lactated Ringer solution at 150 mL/kg/h for 90 minutes. Transthoracic echocardiography was performed before (baseline) and at 15, 30, 45, 60, 75, and 90 minutes after volume loading began. At each echocardiographic assessment point, apical 4-chamber images were recorded and analyzed to derive time-left atrial area curves. Left atrial total (for reservoir function), passive (for conduit function), and active (for booster-pump function) fractional area changes were calculated from the curves. RESULTS Volume overload resulted in a significant increase from baseline in PCWP from 15 to 90 minutes after volume loading began. All fractional area changes at 15 to 90 minutes were significantly increased from baseline. In multiple regression analysis, quadratic regression models were better fitted to the relationships between PCWP and each of the total and active fractional area changes than were linear regression models. A linear regression model was better fitted to the relationship between PCWP and passive fractional area change. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that left atrial phasic function assessed on the basis of left atrial phasic areas was enhanced during experimental cardiac volume loading in healthy dogs. The effect of volume load should be considered when evaluating left atrial phasic function by indices derived from left atrial phasic sizes.


American Journal of Veterinary Research | 2015

Effects of various cardiovascular drugs on indices obtained with two-dimensional speckle tracking echocardiography of the left atrium and time-left atrial area curve analysis in healthy dogs

Tatsuyuki Osuga; Kensuke Nakamura; Tomoya Morita; Sue Yee Lim; Nozomu Yokoyama; Keitaro Morishita; Hiroshi Ohta; Mitsuyoshi Takiguchi

OBJECTIVE To evaluate the effects of dobutamine, esmolol, milrinone, and phenylephrine on left atrial phasic function of healthy dogs. ANIMALS 9 healthy Beagles. PROCEDURES Following sedation with propofol on each of 4 experimental days, dogs were administered a constant rate infusion of dobutamine (5 μg/kg/min), esmolol (500 μg/kg/min), milrinone (25 μg/kg, IV bolus, followed by 0.5 μg/kg/min), or phenylephrine (2 μg/kg/min). There was at least a 14-day interval between experimental days. Each drug was administered to 6 dogs. Conventional and 2-D speckle tracking echocardiography were performed before (baseline) and after administration of the cardiovascular drug, and time-left atrial area curves were derived to calculate indices for left atrial reservoir, conduit, and booster pump functions (left atrial phasic function) and left ventricular contractility and lusitropy. RESULTS Compared with baseline values, indices for left atrial reservoir and booster pump functions and left ventricular contractility and lusitropy were significantly increased following dobutamine administration; indices for left atrial phasic function and left ventricular lusitropy were changed insignificantly, and indices for left ventricular contractility were significantly impaired following esmolol administration; indices for left atrial phasic function and left ventricular relaxation were changed insignificantly, and indices for left ventricular systolic function were significantly augmented following milrinone administration; and indices for left atrial phasic function and left ventricular lusitropy were changed insignificantly, and indices of ventricular contractility were significantly impaired following phenylephrine administration. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that, following administration of dobutamine, esmolol, milrinone, or phenylephrine to healthy dogs, left atrial phasic function indices were fairly stable and did not parallel changes in left ventricular function indices.


Journal of Veterinary Medical Science | 2017

Repeatability and reproducibility of quantitative contrast-enhanced ultrasonography for assessing duodenal perfusion in healthy dogs

Khoirun Nisa; Sue Yee Lim; Masayoshi Shinohara; Noriyuki Nagata; Kazuyoshi Sasaoka; Angkhana Dermlim; Rommaneeya Leela-Arporn; Tomoya Morita; Nozomu Yokoyama; Tatsuyuki Osuga; Noboru Sasaki; Keitaro Morishita; Kensuke Nakamura; Hiroshi Ohta; Mitsuyoshi Takiguchi

Contrast-enhanced ultrasonography (CEUS) with microbubbles as a contrast agent allows the visualization and quantification of tissue perfusion. The assessment of canine intestinal perfusion by quantitative CEUS may provide valuable information for diagnosing and monitoring chronic intestinal disorders. This study aimed to assess the repeatability (intraday variability) and reproducibility (interday variability) of quantitative duodenal CEUS in healthy dogs. Six healthy beagles underwent CEUS three times within one day (4-hr intervals) and on two different days (1-week interval). All dogs were sedated with a combination of butorphanol (0.2 mg/kg) and midazolam (0.1 mg/kg) prior to CEUS. The contrast agent (Sonazoid®) was administered using the intravenous bolus method (0.01 ml/kg) for imaging of the duodenum. Time-intensity curves (TIC) were created by drawing multiple regions of interest (ROIs) in the duodenal mucosa, and perfusion parameters, including the time-to-peak (TTP), peak intensity (PI), area under the curve (AUC), and wash-in and wash-out rates (WiR and WoR, respectively), were generated. Intraday and interday coefficients of variation (CVs) for TTP, PI, AUC, WiR and WoR were <25% (range, 2.27–23.41%), which indicated that CEUS was feasible for assessing duodenal perfusion in healthy sedated dogs. A further study of CEUS in dogs with chronic intestinal disorders is necessary to evaluate its clinical applicability.


Journal of Veterinary Medical Science | 2018

The effect of sedation with a combination of butorphanol and midazolam on quantitative contrast-enhanced ultrasonography of duodenum in healthy dogs

Khoirun Nisa; Sue Yee Lim; Tatsuyuki Osuga; Nozomu Yokoyama; Masahiro Tamura; Noriyuki Nagata; Kazuyoshi Sasaoka; Angkhana Dermlim; Rommaneeya Leela-Arporn; Tomoya Morita; Noboru Sasaki; Keitaro Morishita; Kensuke Nakamura; Hiroshi Ohta; Mitsuyoshi Takiguchi

Quantitative contrast-enhanced ultrasonography (CEUS) enables non-invasive and objective evaluation of intestinal perfusion by quantifying the intensity of enhancement on the intestine after microbubble contrast administration. During CEUS scanning, sedation is sometimes necessary to maintain animal cooperation. Nevertheless, the effect of sedative administration on the canine intestinal CEUS is unknown. This study aimed to investigate the effect of sedation with a combination of butorphanol and midazolam on the duodenal CEUS-derived perfusion parameters of healthy dogs. For this purpose, duodenum was imaged following contrast administration (Sonazoid®, 0.01 ml/kg) in six healthy beagles before and after intravenous injection of a combination of butorphanol (0.2 mg/kg) and midazolam (0.1 mg/kg). Furthermore, hemodynamic parameters including blood pressure and heart rate were recorded during the procedure. Five CEUS derived perfusion parameters including time-to-peak (TTP), peak intensity (PI), area under the curve (AUC), wash-in and wash-out rates (WiR and WoR, respectively) before and after sedation were statistically compared. The result showed that no significant change was detected in any of perfusion parameters. Systolic and mean arterial pressures significantly reduced after sedative administration, but diastolic arterial pressure and heart rate did not significantly change. Moreover, no significant partial correlation was observed between perfusion parameters and hemodynamic parameters. Thus, we concluded that the combination did not cause significant influence in duodenal CEUS perfusion parameters and could be a good option for sedation prior to duodenal CEUS in debilitated dogs.

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Sue Yee Lim

Universiti Putra Malaysia

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