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Background: Pulmonary hypertension (PH) secondary to respiratory disease is caused by pulmonary vascular remodeling and hypoxia. Severe PH can induce various clinical signs, including syncope and right‐sided heart failure. Hypothesis/Objectives: To investigate the echocardiographic characteristics in dogs with PH secondary to respiratory diseases. Animals: Thirty‐one dogs with respiratory diseases with or without PH and 15 healthy dogs. Methods: Prospective cross‐sectional study. Dogs were classified according to respiratory disease (obstructive airway/lung disease [OALD] or restrictive lung disease [RLD]) and PH‐relevant signs. The association between echocardiographic variables and PH (classified by respiratory disease and PH‐relevant signs) was investigated. Results: Twenty‐one dogs were diagnosed with PH; of these, 11 showed PH‐related signs (OALD, n = 2; RLD, n = 9), 14 had right ventricular hypertrophy, and 19 had pulmonary arterial enlargement. Right ventricular dysfunction and dilatation were observed only in dogs with PH‐related signs (n = 10). Left and right ventricular stroke volumes were significantly lower in dogs with PH (median [interquartile range]: 17.2 [12.4‐20.8] and 16.8 [15.3‐29.5] mL/m2, respectively). Dogs with RLD had higher echocardiography‐estimated pulmonary vascular resistance than those with OALD (median [interquartile range]: 3.1 [1.9‐3.3] and 1.6 [1.3‐2.2], respectively). Conclusions and Clinical Importance: Pulmonary arterial enlargement was the most common echocardiographic finding in dogs with PH secondary to respiratory diseases. Right ventricular dysfunction, dilatation, and decreased left and right ventricular stroke volume were significantly associated with the PH‐related signs, indicating that comprehensive echocardiography is recommended in dogs with respiratory disease. Restricted lung disease might induce more severe PH than OALD. [ABSTRACT FROM AUTHOR]

Background: Progression to combined post‐ and pre‐capillary pulmonary hypertension (PH) provides prognostic information in human patients with post‐capillary PH. Pulmonary vascular resistance estimated by echocardiography (PVRecho) is useful for the stratification of dogs with myxomatous mitral valve disease (MMVD) and detectable tricuspid regurgitation. Objectives: To evaluate the prognostic value of PVRecho in dogs with MMVD. Animals: Fifty‐four dogs with MMVD and detectable tricuspid regurgitation. Methods: Prospective cohort study. All dogs underwent echocardiography. The PVRecho was calculated based on tricuspid regurgitation and the velocity‐time integral of the pulmonary artery flow. To evaluate the influence of echocardiographic variables on cardiac‐related deaths, Cox proportional hazard analysis was performed. Additionally, Kaplan‐Meier curves classified by PVRecho tertiles were made and compared using log‐rank tests to evaluate the influence of PVRecho on all‐cause mortality and cardiac‐related death. Results: The median follow‐up time was 579 days. Forty‐one dogs with MMVD (PH severity [number]: no or mild, 21/33; moderate, 11/11; severe, 9/10) died during the study. In the multivariable Cox proportional hazard analysis adjusted for age, sildenafil administration, and American College of Veterinary Internal Medicine stage of MMVD, left atrial to aortic diameter ratio and PVRecho remained significant (adjusted hazard ratio [95% confidence interval]: 1.2 [1.1‐1.3] and 2.1 [1.6‐3.0], respectively). Higher PVRecho showed a significant association with lower survival rates. Conclusions and Clinical Importance: Left atrial enlargement and high PVRecho were independent prognostic factors in dogs with MMVD and detectable tricuspid regurgitation. [ABSTRACT FROM AUTHOR]

Mesenchymal stem cells (MSC) are currently being investigated for their therapeutic applications in a wide range of diseases. Although many studies examined peripheral venous administration of MSC, few have investigated the detailed intravenous administration procedures of MSC from their preparation until they enter the body. The current study therefore aimed to explore the most efficient infusion procedure for MSC delivery by preparing and infusing them under various conditions. Canine adipose-derived mesenchymal stem cells (cADSC) were infused using different infusion apparatuses, suspension solutions, allogenic serum supplementation, infusion time and rates, and cell densities, respectively. Live and dead cell counts were then assessed by manual measurements and flow cytometry. Efficiency of live- and dead-cell infusion and cell viability were calculated from the measured cell counts and compared under each condition. Efficiency of live-cell infusion differed significantly according to the infusion apparatus, infusion rate, and combination of cell density and serum supplementation. Cell viability after infusion differed significantly between the infusion apparatuses. The optimal infusion procedure resulting in the highest cell delivery and viability involved suspending cADSC in normal saline supplemented with 5% allogenic serum at a density of 5 × 105 cells/mL, and infusing them using an automatic infusion device for 15 min. This procedure is therefore recommended as the standard procedure for the intravenous administration of ADSC in terms of cell-delivery efficiency. [ABSTRACT FROM AUTHOR]

Real-time three-dimensional echocardiography (RT3DE) enables a noninvasive assessment of right ventricular (RV) morphology. However, no study has evaluated the relationship between RV function obtained by RT3DE and RV pressure-volume loops. This hypothesis-driven, experimental study aimed to assess the utility of RT3DE in the evaluation of RV morphology and function. Ten anesthetized beagle dogs sequentially underwent dobutamine infusion, acute infusion of lactated Ringer's solution, and furosemide administration to alter RV contractility and loading conditions. RV pressure-volume loop-derived hemodynamic measurements and echocardiography, including two-dimensional speckle-tracking echocardiography and RT3DE, were performed in each study protocol. Bland–Altman analysis showed strong agreement in RV volume, ejection fraction, and stroke volume obtained by right heart catheterization and RT3DE. Multiple regression analyses revealed that the peak myocardial velocity of the lateral tricuspid annulus (RV s') and global RV longitudinal strain rate were significantly associated with end-systolic elastance (adjusted r2 = 0.66, p < 0.001). RV s', RV free wall longitudinal strain, and RT3DE-derived stroke volume/end-systolic RV volume ratio were associated with RV pressure-volume loops-derived end-systolic/arterial elastance ratio (adjusted r2 = 0.34, p < 0.001). RT3DE could detect the changes in catheterization-derived RV volume with a strong agreement and might be useful in estimating RV-pulmonary arterial coupling. [ABSTRACT FROM AUTHOR]

Background: Tricuspid annular plane systolic excursion (TAPSE) is a common right ventricular (RV) function indicator. However, TAPSE was not decreased in dogs with myxomatous mitral valve disease (MMVD) and postcapillary pulmonary hypertension (PH) because of its load, angle, and body weight dependency, and TAPSE was considered a preload‐dependent index. Objectives: To evaluate the utility of TAPSE normalized by RV size in dogs with postcapillary PH. Animals Twenty healthy dogs and 71 MMVD dogs with or without PH. Methods: In this prospective observational study, end‐diastolic RV internal dimension (RVIDd), end‐diastolic and end‐systolic RV area, and end‐diastolic RV wall thickness were measured as RV size indices. The TAPSE was measured using B‐mode and M‐mode methods. Normalized TAPSE was calculated by dividing TAPSE by each RV size index. The RV strain was obtained as the detailed RV function using 2‐dimensional speckle tracking echocardiography. All indices were compared among the PH severity groups and in the presence of right‐sided congestive heart failure (R‐CHF). Results: Although nonnormalized TAPSE was higher with PH severity progression, each normalized TAPSE showed a significant decrease in the severe PH group (P <.05). The TAPSEB‐mode/RVIDd ratio had high area under the curve to predict R‐CHF and had moderate correlation with RV strain (P <.05). The TAPSEB‐mode/RVIDd and left atrial‐to‐aortic diameter ratios were independent predictors for R‐CHF. Conclusions and Clinical Importance: Normalized TAPSE could reflect RV systolic dysfunction in dogs with severe PH, which could not be detected by nonnormalized TAPSE. The TAPSEB‐mode/RVIDd ratio might predict R‐CHF with high sensitivity and reproducibility. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The objective of this study was to evaluate the effect of age on myocardial function assessed by two-dimensional speckle-tracking echocardiography (2D-STE) in healthy dogs. Animals: Thirty-two healthy Beagles were used. Methods: Myocardial function was assessed in each dog by using 2D-STE, and the results were compared between young and old dogs. Results: The myocardial deformations in systole, besides the apical rotation rate, were not significantly different between young and old dogs. In contrast, the early diastolic circumferential strain rate, basal rotation rate, and torsion rate were significantly lower in old dogs than in young dogs (P = 0.03, P = 0.033, and P = 0.015, respectively). Late diastolic longitudinal and radial strain rates were significantly higher in old dogs than in young dogs (P = 0.002 and P = 0.018, respectively). Conclusions: Young and old dogs showed similar systolic myocardial deformations, but significant differences in the values of some diastolic deformation variables were found between young and old dogs, highlighting the need for using age-matched control subjects in studies of diastolic function. [Copyright &y& Elsevier]

Abstract: Objective: The objective of this study was to evaluate the influence of heart rate (HR) on myocardial function assessed by two-dimensional speckle-tracking echocardiography (2D-STE) in healthy dogs. Animals: Thirteen healthy beagle dogs. Methods: Animals were anesthetized and HR was controlled with right atrial pacing. Myocardial function of each dog was assessed using 2D-STE at pacing rates of 120, 140, 160, and 180 bpm. Results: All strain and strain rate variables in the longitudinal, circumferential, and radial directions were not significantly different between pacing rates. Peak early diastolic torsion rate at 180 bpm was significantly increased compared with that at 120 bpm (P = 0.003). Conclusion: Torsion rate in early diastole was elevated at 180 bpm, which may reflect improved myocardial relaxation with higher HR. Changes in left ventricular torsion during tachycardia may play an important role in preserving stroke volume in the presence of shortened ejection and filling times. [Copyright &y& Elsevier]