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

Detection of Congestive Heart Failure and Myocardial Dysfunction in Cats With Cardiomyopathy by Using Two-Dimensional Speckle-Tracking Echocardiography

Congestive heart failure (CHF) is a life-threatening condition in cats with cardiomyopathy. We hypothesized that myocardial dysfunction may induce progression to CHF pathophysiology in cats with cardiomyopathy. However, no previous studies have evaluated the involvement of myocardial dysfunction in cats with CHF. In this study, we aimed to evaluate the relationship between CHF and myocardial function assessed using two-dimensional speckle-tracking echocardiography (2D-STE). Sixteen client-owned healthy cats and 32 cats with cardiomyopathy were enrolled in this study. Cats were classified into three groups: healthy cats, cardiomyopathy without CHF (CM group), and cardiomyopathy with CHF (CHF group). Left ventricular (LV) longitudinal and circumferential strains (SL and SC, respectively), and right ventricular (RV) SL were measured using 2D-STE. Logistic regression analysis was performed to assess the relationship between CHF and echocardiographic variables, including 2D-STE. Results comparing the healthy cats and CM vs. CHF groups showed that increased left atrial to aortic diameter ratio and decreased LV apical SC were significantly associated with the existence of CHF (odds ratio [95% confidence interval]: 1.40 [1.16-1.78] and 1.59 [1.06-2.36], respectively). Results comparing the CM vs. CHF group showed that increased end-diastolic RV internal dimension and decreased RV SL were significantly associated with the existence of CHF (odds ratio: 1.07 [1.00-1.13] and 1.34 [1.07-1.68], respectively). Left atrial enlargement and depressed LV apical myocardial function may be useful tools for predicting the progression to CHF in cats. Furthermore, RV enlargement and dysfunction may lead to the onset of CHF in asymptomatic cats with cardiomyopathy.

Incremental predictive value of echocardiographic indices of right ventricular function in the assessment of long-term prognosis in dogs with myxomatous mitral valve disease

INTRODUCTION

Few studies have evaluated the utility of echocardiographic indices of right ventricular (RV) function in predicting prognosis in dogs with myxomatous mitral valve disease (MMVD).

ANIMALS

Sixty-seven client-owned dogs were diagnosed with MMVD.

MATERIALS AND METHODS

clinical cohort study. Dogs diagnosed with American college of veterinary internal medicine (ACVIM) stage B2, C or D between April 2014 and March 2017 were enrolled. Long-term outcomes were assessed by telephone or from the medical record. The primary end-point was defined as cardiac-related death. Echocardiographic indices of RV function, including the RV Tei index, free wall and septal RV longitudinal strain, were obtained. Univariable and multivariable Cox proportional hazard analyses were used to identify variables predictive of cardiac-related death.

RESULTS

Twenty-four dogs died during the follow-up period. The median follow-up time was 482 days, and the median survival time for dogs with cardiac-related death was 230 days. For cardiac-related death, peak early diastolic mitral inflow velocity, ACVIM stage C or D, tricuspid regurgitation velocity, RV Tei index and RV end-diastolic area were predictors in univariable Cox proportional hazard analysis. In multivariable Cox proportional analysis adjusted for the left atrial to aorta ratio, peak early diastolic mitral inflow velocity and ACVIM stage, an increase in the Tei index by 0.1 increased the hazard ratio of cardiac-related death by 33% (95% confidence interval, 16-70%; P = 0.002).

CONCLUSIONS

In dogs with MMVD, RV dysfunction assessed by the Tei index is an independent predictor of cardiac-related death.

Novel Approach to Assess Cardiac Function Using Systolic Performance and Myocardial Performance Indices From Simultaneous Electrocardiography and Phonocardiography Recordings in Dogs With Various Stages of Myxomatous Mitral Valve Disease

Background and Objective: Myxomatous mitral valve disease (MMVD) progression entails changes in the structural and functional properties of the heart affecting cardiac timings and intervals within the cardiac cycle. Conventionally, echocardiography is used to determine the cardiac time intervals (CTIs) including systolic and myocardial performance indices (SPI and MPI) in evaluating cardiac function. Alternatively, these CTIs can also be measured using simultaneous recordings of electrocardiography (ECG) and phonocardiography (PCG), but their values in different MMVD stages remain to be established. This study aimed to establish and prove the use of derived SPI and MPI from a dedicated device as a novel approach to assess cardiac function in different stages of MMVD dogs. Materials and Methods: A prospective study in 52 dogs with different MMVD stages measured the CTIs using a novel device. These were compared and correlated with standard echocardiographic parameters. The predictive value of SPI and three new proposed formulas to estimate MPI (i.e., F1, F2, and F3) in association with asymptomatic from symptomatic MMVD dogs were investigated. Results: Our findings revealed that CTI parameters measured from a novel device including QS1, QS2, S1S2, MPI-F1, and MPI-F2 were altered at different stages of MMVD. The SPI and all proposed MPI formulas were comparable with the systolic time interval and Tei index from echocardiography. In addition, the SPI, MPI-F1, and MPI-F2 were significantly correlated with the Tei index. However, the SPI was not able to differentiate the various stages of MMVD. Conversely, only the MPI-F1 (i.e., (QS1 + S2)/S1S2) demonstrated good predictive accuracy when compared between asymptomatic and symptomatic MMVD dogs similar to the Tei index. Moreover, this formula was able to differentiate stages B1 and C with remarkable predictive accuracy, higher sensitivity, and high specificity when compared with the Tei index. Conclusion: We have successfully described the CTI parameters in different MMVD stages using simultaneous ECG and PCG recordings in dogs. Furthermore, we have proven that the concept of using the newly proposed parameters from a novel device is equivalent to the Tei index. Thus, we established a novel approach to evaluate cardiac function and its supportive use in the diagnosis of MMVD patients.

Right ventricular systolic and diastolic function assessed by two-dimensional speckle tracking echocardiography in dogs with myxomatous mitral valve disease

Pulmonary hypertension (PH) is a common comorbidity in dogs with myxomatous mitral valve disease (MMVD), and can induce various changes in the right heart, such as right ventricular (RV) hypertrophy, dilatation, and dysfunction. We hypothesized that RV function, not only systolic function but also diastolic function, could be worsened with PH progression. We aimed to compare RV systolic and diastolic function in dogs with MMVD. Twenty healthy dogs and sixty-eight dogs with MMVD were enrolled. Dogs with MMVD were classified into the probability of PH. Two-dimensional and Doppler echocardiographic indices for right heart and two-dimensional speckle tracking echocardiography indices were measured. The morphological indicators of the right heart were significantly higher only in the high probability of PH group. The RV strain, early-diastolic and systolic strain rates were significantly lower in the high probability of PH group than those in the low and intermediate probability of PH groups. Multivariate analysis showed that increased RV internal dimension normalized by body weight and RV myocardial performance index were significantly associated with the presence of right-sided congestive heart failure. Speckle tracking echocardiography-derived RV systolic and diastolic function were activated in the low and intermediate probability of PH groups. However, dogs with high probability of PH showed RV myocardial dysfunction and dilatation. Increased RV myocardial performance index and end-diastolic RV internal dimension normalized by body weight were significantly associated with the presence of right-sided congestive heart failure in dogs with MMVD.

Repeatability, reproducibility, and reference intervals for indices of right atrial longitudinal strain derived from speckle-tracking echocardiography in healthy dogs

OBJECTIVE

To determine repeatability, reproducibility, and reference intervals of indices of right atrial longitudinal strain (RALS) derived from speckle-tracking echocardiography (STE) in dogs without heart disease.

ANIMALS

110 client-owned dogs and 10 laboratory Beagles.

PROCEDURES

To determine intraobserver within-day (repeatability) and interobserver (reproducibility) coefficients of variation, RALS during ventricular systole (ϵS), ventricular early diastole (ϵE), and atrial systole (ϵA), as derived with STE, were obtained by 2 investigators for 5 randomly selected client-owned dogs and analyzed by linear regression. Reference intervals were estimated from the results of all dogs. Correlations between RALS indices (ϵS, ϵE, and ϵA) and sex, age, body weight, heart rate, and blood pressure were determined.

RESULTS

RALS derived from STE showed good intraobserver within-day repeatability and interobserver reproducibility, with coefficients of variation of < 20%. Both ϵS and ϵE were significantly negatively correlated with age, but ϵA was not correlated with age. Indices were not correlated with sex, body weight, or blood pressure.

CONCLUSIONS AND CLINICAL RELEVANCE

RALS indices derived from STE were repeatable and reproducible and were affected by the age of dogs without heart disease. Age should be considered in the interpretation of RALS indices in clinical settings. Further studies are needed to apply RALS indices for assessing dogs with heart disease.

Ultrasonographic evaluation of the caudal vena cava in dogs with right-sided heart disease

INTRODUCTION/OBJECTIVES

In humans with impaired right-sided cardiac function, the caudal vena cava (CVC) diameter serves as a marker of venous congestion. This study aimed to investigate whether ultrasonographic CVC variables could identify the presence of right-sided congestive heart failure (R-CHF) in dogs with right-sided heart disease (RHD).

ANIMALS

Fifty client-owned control dogs and 67 dogs with RHD were enrolled. The dogs with RHD were subdivided into the non-R-CHF (n = 43) and R-CHF (n = 24) groups.

MATERIALS AND METHODS

We measured and compared the ultrasonographic CVC variables and echocardiographic variables among the groups. Receiver operating characteristic (ROC) curve analysis was performed to calculate the sensitivity and specificity of the variables at optimal cutoff values.

RESULTS

We obtained the highest accuracies of the ratio of the shortest diameter (SD) of the minimal CVC area to the aorta diameter (Ao) during inspiration [SD(min)/Ao] and of the ratio of SD(min) to the longest diameter of the minimal CVC area during inspiration [LD(min),SD/LD(min)], with high sensitivities, specificities, and an area under the ROC curve greater than 0.925.

CONCLUSIONS

In addition to the echocardiographic assessment of right-sided cardiac function, the CVC variables in this study, especially SD(min)/Ao and SD/LD(min), would be useful diagnostic indices for identifying R-CHF in dogs with RHD.

Short-term effects of sildenafil in the treatment of dogs with pulmonary hypertension secondary to degenerative mitral valve disease

Background and Aim:

Pulmonary hypertension (PH) is a common complication of degenerative mitral valve disease (DMVD). Sildenafil, a phosphodiesterase-5 inhibitor, has effects in reducing pulmonary arterial pressure by selectively dilating pulmonary vessels. The study aimed to evaluate the effects of sildenafil in combination with conventional therapy in dogs with PH caused by DMVD.

Materials and Methods:

Fourteen dogs diagnosed with PH secondary to DMVD Stage C on conventional therapy were randomly assigned to placebo (n=7) and sildenafil (n=7) groups. On day 0, the recruited dogs underwent physical examinations, clinical score assessments, electrocardiography, systolic blood pressure measurements, blood collection, thoracic radiography, and echocardiography for baseline. The dogs then received a combination of conventional therapy with sildenafil or placebo every 8 h for 1 week. On day 7, all dogs underwent the baseline evaluations again.

Results:

The sildenafil group experienced a significant decrease in estimated systolic pulmonary artery pressure (sPAP) (p=0.043) from day 0 to day 7. Moreover, the total clinical scores were decreased in dogs treated with sildenafil relative to those who received the placebo (p=0.007); however, the lung scores were not different between before and after treatment with sildenafil.

Conclusion:

Sildenafil had a synergistic effect with conventional therapy in reducing the estimated sPAP and clinical scores in dogs with PH secondary to DMVD.

Transverse Right Ventricle Strain and Strain Rate Assessed by 2-Dimensional Speckle Tracking Echocardiography in Dogs with Pulmonary Hypertension

Right ventricular (RV) strain analysis using 2-dimensional speckle tracking echocardiography (2D STE) permits practitioners to assess regional and global deformation of the myocardium. Recently, assessment of the longitudinal right ventricle (RV) strain and strain rate using 2D STE has been reported in dogs. Although longitudinal deformation is the dominant component of the RV systole, RV myocardial fibers of the superficial layer are oriented circumferentially and these contribute to the RV pump function (radial deformation). Because this strain component has not been investigated in dogs, we have assessed radial RV strain and strain rate using 2D STE in healthy dogs and dogs with pulmonary hypertension (PH). We have recruited 74 dogs (40 healthy dogs and 34 dogs with PH) in which we have analyzed radial RV free wall strain and strain rate using XstrainTM software. We have used the left apical 4-chamber view optimized for the RV for analysis of the radial strain and strain rate variables (XstrainTM software denoted radial strain as "transverse"). Seven dogs were excluded during the analysis for low quality images. Transverse strain and strain rate obtained in healthy dogs showed no relationship with heart rate, body weight or age (r2 < 0.09 and p > 0.05 for all variables). Moreover, no relationship between transverse strain/strain rate variables and left atrial-to-aortic ratios was observed (r2 < 0.06 and p = 0.2, for both). Transverse strain and strain rate obtained in dogs with PH, showed weak negative relationships with tricuspid regurgitation velocity (r2 < 0.25 and p = 0.006, for both). Transverse RV strain and strain rate using 2D STE is feasible in most dogs and decrease with worsening of the PH, but these advanced echocardiographic indices do not help in identifying dogs with PH.

Effect of temperature variation on hospital admissions and outcomes in dogs with myxomatous mitral valve disease and new onset pulmonary edema

The effect of seasonal variation on hospital admissions and outcomes in humans with cardiovascular disease and congestive heart failure (CHF) has been described. This study evaluates the effect of temperature variation on admissions and outcomes in dogs with myxomatous mitral valve disease (MMVD) and first onset CHF. Ninety-three client-owned dogs with MMVD and a first occurrence of pulmonary edema were included in this retrospective clinical cohort study. Recorded clinical and echocardiographic variables were accumulated and analyzed with dogs allocated into groups in a temperature-wise manner that considered the mean of the average (Tave) and maximum ambient temperature (Tmax) of the 14 days preceding hospital admission. A survival analysis was also performed. No difference was found in the percentage of dogs decompensating in three different temperature periods (i.e., cold, intermediate, and hot temperature) according to both Tave and Tmax. Dogs developing CHF during the intermediate temperatures according to Tmax died earlier from cardiac-related causes (median survival time 280 days, 95% CI = 147–486 days) compared to those decompensating during hot temperatures (median survival time 518 days, 95% CI = 344–819 days, P = 0.039). However, an effect of the ambient temperature on survival was not confirmed by Cox proportional hazard analysis. In conclusion, this study failed to show that ambient temperature has an effect on the first occurrence of CHF and outcomes in dogs with MMVD.

Prognostic value of right pulmonary artery distensibility in dogs with pulmonary hypertension

The right pulmonary artery distensibility (RPAD) index has been used in dogs with pulmonary hypertension (PH) caused by heartworm infection, myxomatous mitral valve disease, or patent ductus arteriosus. We hypothesized that this index correlates with the tricuspid regurgitation pressure gradient (TRPG) assessed by echocardiography and could predict survival in dogs with PH secondary to various causes. To assess this hypothesis, the medical records of 200 client-owned dogs at a referral institution were retrospectively reviewed. The RPAD index and the ratios of acceleration time to peak pulmonary artery flow (AT) and to the ejection time of pulmonary artery flow (ET) were recorded for each dog. The owners were contacted for follow-up assessments. The findings indicated that the RPAD index was correlated with the TRPG (R² = 0. 362, p < 0.001). The survival time was significantly shorter in dogs with an RPAD index ≤ 21% that were followed up for 3 months and in dogs with an RPAD index ≤ 24% that were followed up for 1 year. Thus, the RPAD index was correlated with the TRPG and could predict the clinical outcome in dogs with PH caused by various diseases. This index could be used to evaluate the severity of PH in dogs without tricuspid regurgitation.

Electrocardiographic and echocardiographic evaluation in dogs with hypothyroidism before and after levothyroxine supplementation: A prospective controlled study

Background

Improvement in cardiac function has been demonstrated after thyroxine treatment in humans with hypothyroidism using the myocardial performance index (MPI). Cardiac changes after thyroxine supplementation are poorly documented in dogs with spontaneous hypothyroidism and comparison with clinically healthy dogs is lacking.

Objectives

To evaluate the electrical activity and mechanical function of the heart in dogs with primary hypothyroidism at baseline (T0) and after thyroxine supplementation (T60).

Animals

Forty client‐owned dogs with hypothyroidism and 20 clinically healthy dogs.

Methods

Prospective cohort study. Selected electrocardiographic and echocardiographic variables, including the MPI, were measured in all dogs at T0 and in 30 hypothyroid dogs at T60.

Results

Hypothyroid dogs had significantly decreased median or mean heart rate (HR), P wave amplitude, and R wave amplitude (P = .04, P = .002, and P = .003, respectively) and E‐point‐to‐septal separation normalized to body weight (EPSSn) and trans‐mitral E wave velocity (E max; P < .001 and P = .025, respectively) at T0 compared to control dogs. At T60, significantly increased median or mean HR, P wave amplitude, fractional shortening, and E max (P < .001, P = .004, P = .002, and P = .009, respectively) and significantly decreased left ventricular end‐diastolic volume index, and normalized systolic diameter and EPSSn (P = .03, P = .03, and P = .001, respectively) were found.

Conclusions and Clinical Importance

Hypothyroidism in dogs induces mild and reversible changes of electromechanical cardiac function. The MPI does not have clinical importance in identifying cardiac dysfunction in affected dogs.

Clinical efficacy of tadalafil compared to sildenafil in treatment of moderate to severe canine pulmonary hypertension: a pilot study

INTRODUCTION

Canine pulmonary hypertension (PH) is associated with high morbidity and mortality. Tadalafil, a phosphodiesterase-5 inhibitor used commonly in humans with PH, has not been evaluated in a clinical trial in dogs with naturally occurring PH. Our objectives were to compare the efficacy of tadalafil and sildenafil on PH assessed by peak tricuspid regurgitant flow velocity, estimated systolic pulmonary arterial pressure gradient, voluntary activity, quality of life, and safety profiles in dogs with moderate to severe PH.

ANIMALS

Twenty-three dogs with echocardiographic evidence of moderate to severe PH were enrolled.

METHODS

A prospective short-term, randomized, double-blinded pilot study was carried out. Dogs with PH were randomly allocated to receive sildenafil or tadalafil for 2 weeks and assessed via echocardiography, activity monitors, and owner-reported outcomes.

RESULTS

Collectively, phosphodiesterase-5 inhibition significantly decreased (improved) quality of life scores (p = 0.003) and visual analog score (p = 0.024) without significant between-treatment difference of these variables. Phosphodiesterase-5 inhibition did not significantly affect peak tricuspid regurgitant flow velocity (p = 0.056) or voluntary activity (p = 0.27). A total of 33% (7/21) of dogs experienced at least one adverse event during the study (tadalafil, n = 5; sildenafil, n = 2) with no significant difference between treatment type and incidence of adverse events (p = 0.36).

DISCUSSION

In this pilot study, phosphodiesterase-5 inhibition led to apparent improvement in quality of life scores without documenting superiority of tadalafil over sildenafil.

CONCLUSION

Tadalafil at a dose of 2 mg/kg once daily appears to be a viable alternative to sildenafil in dogs with moderate to severe PH.

Right ventricular function and dyssynchrony measured by echocardiography in dogs with precapillary pulmonary hypertension

INTRODUCTION

Assessment of the right ventricular (RV) function by echocardiography is important in dogs with pulmonary hypertension (PH). Few reports are available on RV function and dyssynchrony in dogs, especially in the context of precapillary PH.

ANIMALS

The study included 79 client-owned dogs: 25 dogs with precapillary PH and 54 control dogs.

METHODS

Dogs with precapillary PH were prospectively enrolled between December 2013 and February 2017. The echocardiographic indices of RV function, including RV strain and the dyssynchrony index by speckle-tracking echocardiography, were measured. Multivariate analysis was used to determine independent predictors of the RV dyssynchrony index.

RESULTS

Dogs with precapillary PH showed RV dilation, hypertrophy and right atrial dilation. Impaired echocardiographic indices of RV function, including RV strain, were observed. In addition, RV dyssynchrony occurred in dogs with precapillary PH. Multivariate analysis revealed that tricuspid regurgitation velocity and RV dilation were independent predictors of the RV dyssynchrony index.

CONCLUSIONS

Echocardiographic RV function indices are impaired in dogs with precapillary PH. In addition, RV dilation and elevated systolic pulmonary arterial pressure estimated by echocardiography are associated with RV dyssynchrony.

Echocardiographic Estimates of Right Ventricular Systolic Function in Dogs with Myxomatous Mitral Valve Disease

Background

Right ventricular (RV) dysfunction independently predicts outcomes in human myxomatous mitral valve disease (MMVD). There is limited information regarding RV systolic function in dogs with MMVD.

Hypothesis

Right ventricular systolic function differs among stages of disease, decreasing in decompensated MMVD.

Animals

Thirty‐sixclient‐owned dogs with MMVD not receiving oral cardiovascular medications.

Methods

Prospective clinical study. Dogs were categorized according to disease severity as ACVIM Stage B1, B2, or C. Seven echocardiographic indices of RV systolic function were measured. Groups were compared by 1‐way ANOVA and Tukey's HSD test. Frequencies of cases with cardiac remodeling falling outside previously established reference intervals were compared using Fisher's exact test. Intra‐ and interobserver measurement variability was calculated for each RV function index.

Results

The indices TAPSE (P = 0.029), RV St_L (P = 0.012), and RV StR_L (P = 0.041) were significantly different between groups. A greater proportion of B2 dogs (7 of 12) had TAPSE values above reference intervals compared with B1 (2 of 12) or C (2 of 12) dogs (P = 0.027). Measurement variability of TAPSE, RV S', and RV St_G was clinically acceptable.

Conclusions and Clinical Importance

Right ventricular systolic function differs between stages of MMVD, increasing in stage B2, and declining in stage C. The prognostic importance of RV function indices, particularly TAPSE, might be worth evaluating in dogs with MMVD.

Echocardiographic Assessment of Right Ventricular Size and Function in Cats With Hypertrophic Cardiomyopathy

Background

Studies evaluating right ventricular (RV) structural and functional abnormalities in feline hypertrophic cardiomyopathy (HCM) are limited.

Hypothesis

Right ventricular structural and functional abnormalities are present in cats with HCM and are associated with clinical severity.

Animals

Eighty‐one client‐owned cats.

Methods

Retrospective 2‐dimensional (2D) echocardiographic study. Right atrial diameter (RAD), RV free wall thickness (RVFWd), RV internal dimension (RVIDd), RV fractional area change (FAC), and tricuspid annular plane systolic excursion (TAPSE) were measured in control cats (n = 26), cats with subclinical HCM (subclinical HCM; n = 31), and cats with HCM and congestive heart failure (HCM + CHF; n = 24).

Results

Right heart size (RAD, RVFWd, and RVIDd) and RV function (FAC and TAPSE) significantly (all P < .05) increased and decreased, respectively, in the HCM + CHF group compared with controls. In the subclinical HCM group, only RVFWd was significantly (P < .05) higher than in controls. Compared with reference intervals derived from controls, 29% of cats with HCM had increased RVFWd. Increased left ventricular free wall thickness, increased RVIDd and decreased TAPSE independently correlated with increased left atrial size. Cats with HCM and pleural effusion were significantly more likely to have increased RVFWd and had increased RAD and decreased TAPSE compared with cats without pleural effusion.

Conclusions and Clinical Importance

Right ventricular remodeling and dysfunction occur in some cats with HCM and may be associated with clinical severity. Our results support involvement of RV in the pathophysiology of HCM in some cats and support echocardiographic assessment of the RV in cats with HCM.