Left atrial anteroposterior diameter in dogs: reference interval, allometric scaling, and agreement with the left atrial-to-aortic root ratio

Comparative evaluation of left atrial size in healthy cats measured by two-dimensional echocardiography and cardiovascular MRI

OBJECTIVES

This study aimed to assess left atrial (LA) size in healthy cats using cardiovascular MRI (cMRI) and to compare this with LA size assessed by two-dimensional echocardiography. The hypothesis was that cMRI would accurately determine LA size in domestic cats.

METHODS

A prospective comparative study was performed. Six healthy cats were selected for the study. Standard two-dimensional echocardiography was performed with and without general anaesthesia. cMRI was conducted under general anaesthesia. A comprehensive analysis of LA mass and function measurements was performed to determine the consistency and correlation of LA size and function indicators between two-dimensional echocardiography and cMRI.

RESULTS

Our study found that intraobserver variability for cMRI measurements was lower than that for two-dimensional echocardiography. Compared with cMRI, echocardiography under anaesthesia significantly overestimated maximal LA volume (LAVmax_2D, P <0.01) and significantly underestimated minimal LA volume (LAVmin_2D, P <0.01). The LAVmin measured by two-dimensional echocardiography exhibited the highest consistency (intraclass correlation coefficient = 0.857) and correlation (R = 0.75, P <0.01) with LAVmin measured by cMRI. The linear regression equation was LAVmin_ cMRI = 0.891 × LAVmin_2D + 0.304.

CONCLUSIONS AND RELEVANCE

cMRI represents a reproducible method for assessing LA mass in domestic cats. This study underscored the importance of echocardiography in veterinary cardiology, and the LAVmin measured by two-dimensional echocardiography may reflect the true LAVmin.

The impact of intravenous medetomidine and vatinoxan on echocardiographic evaluation of dogs with stage B1 mitral valve disease

INTRODUCTION/OBJECTIVE

The purpose of this study was to investigate the echocardiographic effects of intravenous medetomidine and vatinoxan in dogs with stage B1 mitral valve disease. We hypothesised medetomidine-vatinoxan would reduce the need for manual restraint during echocardiography without producing detrimental cardiovascular effects or echocardiographic changes.

ANIMALS

Twelve client-owned dogs with stage B1 mitral valve disease.

METHODS

A transthoracic echocardiographic examination was performed before and after sedation with intravenous medetomidine (10 μg/kg) and vatinoxan (200 μg/kg). Vital parameters were also recorded, and the level of sedation was assessed subjectively. The data were analysed with Student's t-tests with an alpha level of <0.05.

RESULTS

End-systolic volume and left ventricular systolic diameter increased (from 0.89 ± 0.19 mL/kg to 1.13 ± 0.29 mL/kg and 0.96 ± 0.12 cm to 1.10 ± 0.10 cm, respectively) and ejection fraction (from 66.33 ± 4.0% to 56.23 ± 9.54%) and fractional shortening (from 36.13 ± 5.42% to 27.24 ± 5.6%) decreased significantly after sedation. End diastolic volume, left ventricular diastolic diameter, and left atrial size remained statistically unchanged, while aortic (from 1.34 ± 0.2 m/s to 0.99 ± 0.14 m/s) and pulmonic (from 0.94 ± 0.16 m/s to 0.66 ± 0.15 m/s) velocities decreased significantly. No dogs had a mean arterial pressure below 65 mmHg. Sedation enabled echocardiographic examination without manual restraint. No adverse effects were observed with the dose studied.

CONCLUSIONS

Echocardiographic parameters were not completely comparable with the baseline values, which should be taken into consideration when evaluating dogs sedated with intravenous medetomidine-vatinoxan.

Reference intervals for various measurements of canine left atrial size and function obtained using two-dimensional and three-dimensional echocardiography

BACKGROUND

Many canine cardiac diseases are associated with left atrial (LA) remodeling and decreased function. For accurate assessment of LA indices, large-scale and prospectively determined reference intervals are necessary.

OBJECTIVES

To generate reference intervals of LA size and function using two-dimensional and three-dimensional echocardiography.

ANIMALS

Two hundred and one healthy adult dogs.

METHODS

Left atrial volume was assessed in right parasternal long-axis, left apical 4-chamber and 2-chamber views using monoplane Simpson's method, two-dimensional and three-dimensional speckle tracking. Additionally, LA diameter was measured in right parasternal short-axis and long-axis views. Furthermore, LA function was determined by measuring strain and calculating LA fractional shortening and ejection fraction. All variables were tested for correlation to heart rate, age, and body weight. For LA diameter and volume, scaling exponents and prediction intervals were generated using allometric scaling. Reference intervals for LA function parameters were calculated using nonparametric methods.

RESULTS

Left atrial diameter and volume showed a strong correlation with body weight. The scaling exponent for LA diameter was approximately 1/3 (0.34-0.40) and approximately 1 for volume measurements (0.97-1.26). Parameters of LA function showed no clinically relevant correlation with body weight, except for two variables, which showed a mild negative correlation. No clinically relevant correlations with age or heart rate were found.

CONCLUSIONS

Reference intervals for linear, two-dimensional and three-dimensional measurements of LA size and function were established. The wide range of measurement methods offers the opportunity to select the appropriate reference values for LA evaluation depending on the available technical possibilities.

Echocardiographic reference intervals of the dimensions of the main pulmonary artery and the right pulmonary artery: a prospective study in 269 healthy dogs

INTRODUCTION

No data are available on the echocardiographic reference intervals (RIs) for the main pulmonary artery (MPA) and right pulmonary artery (RPA) dimensions in a large sample of dogs. Therefore, we aimed to describe the echocardiographic RIs of the MPA and RPA dimensions in normal dogs.

ANIMALS, MATERIALS, AND METHODS

Two hundred and sixty nine healthy dogs of different breeds, age and body weight (BW) were prospectively enrolled in this multicenter, observational study. The MPA diameter, RPA maximum diameter (RPAmax), and RPA minimum diameter (RPAmin) were measured from the right parasternal short axis view. Prediction intervals (PIs) for MPA, RPAmax and RPAmin were generated using allometric scales. Reference intervals (RI) of MPA indexed to the ascending aorta (MPA/AO), and RPAmax and RPAmin indexed to the aortic annulus (RPAmax/Aod and RPAmin/Aod), were defined.

RESULTS

A positive linear relationship between MPA, RPAmax, RPAmin and BW was evident after logarithmic transformation (R2 = 0.859, R2 = 0.787 and R2 = 0.725, respectively; P<0.0001). According to allometric scales, the PI for the MPA normalized for BW (MPA_N) was between 5.50 and 8.07, the PI for the RPAmax normalized for BW (RPAmax_N) was between 3.23 and 5.62, while the PI for the RPAmin normalized for BW (RPAmin_N) was between 1.62 and 3.30. The median MPA/AO was 0.92 (RI, 0.78-1.01), the median RPAmax/Aod was 0.70 (RI, 0.53-0.98) and the median RPAmin/Aod was 0.40 (RI, 0.29-0.61).

DISCUSSION AND CONCLUSIONS

The reported RIs of the MPA and RPA dimensions in normal dogs could increase the diagnostic accuracy of transthoracic echocardiography in the identification of pulmonary artery enlargement in dogs.

Surgical correction of an infundibular pulmonic stenosis and ventricular septal defect in a Shetland Sheepdog

A four-month-old male Shetland Sheepdog presented with exercise intolerance. Physical examination revealed an IV/VI left cranial systolic heart murmur. Echocardiography showed a severe infundibular pulmonic stenosis and a concomitant restrictive ventricular septal defect. As clinical signs of congestive right-sided heart failure worsened and were refractory to medical treatment, surgical correction was advised. Via sternotomy, with cardiopulmonary bypass and cardioplegic cardiac arrest, ventricular septal defect closure and resection of the stenotic infundibular band were performed through right ventriculotomy, followed by patch enlargement. Postoperative recovery was uneventful and echocardiography showed complete resolution of the stenosis and successful closure of the ventricular septal defect. Follow-up echocardiography revealed restenosis after seven weeks and recurrence of right-sided heart failure three months postoperatively. Stenting of the restenosis was attempted via a hybrid procedure with sternotomy and direct transventricular approach. The dog developed fatal ventricular fibrillation during stent deployment. This is the first dog in which surgical right ventricular patch enlargement under cardiopulmonary bypass is reported for the treatment of a primary infundibular pulmonic stenosis.

Possible development and resolution of dilated cardiomyopathy phenotype secondary to atypical hypoadrenocorticism in a dog

OBJECTIVE

To report the possible occurrence of dilated cardiomyopathy phenotype associated with atypical hypoadrenocorticism and subsequent marked improvement with treatment in a mixed breed dog.

CASE SUMMARY

A 4.5-year-old, neutered male mixed breed dog was evaluated for a history and clinicopathological changes consistent with atypical hypoadrenocorticism. The dog was being fed a grain-free diet. While hospitalized for supportive care and diagnostics, the patient developed and was diagnosed with biventricular congestive heart failure secondary to dilated cardiomyopathy phenotype and IV fluid administration. The left-sided congestive heart failure resolved with discontinuation of IV fluid therapy and short-term administration of diuretics. After treatment of atypical hypoadrenocorticism with glucocorticoid supplementation, and while continuing to be fed varying grain-free diets, the patient's dilated cardiomyopathy phenotype largely resolved. The patient fully recovered and did not require any long-term cardiac medications.

NEW OR UNIQUE INFORMATION PROVIDED

Development of dilated cardiomyopathy phenotype has not been described in dogs as a sequela of untreated hypoadrenocorticism but has been reported in human literature. Given the fact that standard management of hypoadrenocorticism typically involves aggressive fluid resuscitation, awareness of this potential sequela is important for patients that fail to respond or develop signs consistent with volume overload.

Echocardiographic values in healthy Pugs: Effect of body weight, age, and sex

Background

Transthoracic echocardiography represents the main noninvasive technique for evaluating cardiac morphology and function in dogs. In dogs with particular somatotypes, such as brachymorphic dogs, breed-specific echocardiographic values are needed for a proper echocardiographic interpretation. Nowadays, the Pug represents one of the most popular brachymorphic canine breeds worldwide. However, data on echocardiographic measurements in this breed are currently limited.

Aim

We aimed to determine echocardiographic values in a population of apparently healthy Pugs, and to assess the possible effects of body weight (BW), age, and sex on selected echocardiographic variables, with particular emphasis on those related to the left-sided cardiac chambers.

Methods

Apparently healthy Pugs underwent a full physical examination, a 1-minute six-lead electrocardiogram, and a complete transthoracic echocardiography. Twenty-four echocardiographic variables were measured by combining M-mode, two-dimensional and Doppler modalities, and relative values were determined by applying the statistical procedures recommended by the Clinical and Laboratory Standards Institute. Moreover, the effect of selected demographic variables on echocardiographic measurements was tested using a linear mixed model.

Results

The investigation included 86 Pugs. Echocardiographic values were provided for each variable and compared with previous veterinary literature. A statistically significant effect of BW, age, and sex was documented for several of the tested variables. Doppler examination demonstrated a trivial pulmonary regurgitation in 24/86 (27.9%) Pugs. Moreover, a persistent left cranial vena cava was suspected in 4/86 (4.7%) dogs.

Conclusion

Echocardiographic features of the Pug were addressed and echocardiographic values were made available for clinical use. Because our findings were obtained using a standardized echocardiographic analysis in a population of 86 healthy Pugs, they may act as a reliable guide for an accurate echocardiographic interpretation in this breed.

Two-dimensional echocardiographic estimates of left atrial volumes obtained from two different views in dogs are similar but not interchangeable

Left atrial (LA) volumes using a monoplane Simpson's Method of Discs (SMOD) can be obtained from the right parasternal long axis four-chamber (RPLA) or from the left apical four-chamber (LA4C) views in dogs; however, little information exists regarding the agreement of LA volume estimates using a SMOD on images obtained from LA4C and RPLA views. Therefore, we sought to examine the agreement between the two methods of obtaining LA volumes in a heterogenous population of healthy and diseased dogs. Additionally, we compared the LA volumes obtained by SMOD with estimates obtained from simple cube or sphere volume formulae. Archived echocardiographic examinations were retrieved and, where both RPLA and LA4C views were adequately recorded, included in the study. We obtained measurements from 194 dogs that were either apparently healthy (n = 80) or had various cardiac diseases (n = 114). The LA volumes of each dog was measured using a SMOD, from both views, in systole and diastole. Estimates of LA volumes obtained from simple cube or sphere volume formulae from RPLA-derived LA diameters were also calculated. We then used Limits of Agreement analysis to determine agreement between the estimates obtained with each view, and those calculated from linear dimensions. The two methods obtained by SMOD provided similar estimates for both systolic and diastolic volumes but did not agree sufficiently to be interchangeable. The LA4C view often slightly underestimated the LA volumes at small LA sizes and overestimated the LA volumes at large LA sizes compared to RPLA method, with increasing disagreement as the LA size increased. Estimates based on cube method overestimated volumes compared to both SMOD methods, whereas those based on sphere method performed reasonably. Our study suggests that monoplane volume estimates from the RPLA and LA4C views are similar but not interchangeable. Clinicians can also perform a rough estimate of LA volumes using RPLA-derived LA diameters to calculate the sphere volume.

Prospective pilot study on the predictive significance of plasma miR-30b-5p through the study of echocardiographic modifications in Cavalier King Charles Spaniels affected by different stages of myxomatous mitral valve disease: The PRIME study

Specific microRNAs expressions may accurately characterize different stages of canine myxomatous mitral valve disease. This preliminary pilot study aimed to (1) describe the clinical and echocardiographic parameters of Cavalier King Charles Spaniels affected by myxomatous mitral valve disease at different American College of Veterinary Internal Medicine (ACVIM) stages (B1, B2 and C) and healthy control group (ACVIM A), comparing the parameters collected during the first examination (T0) and the end of the follow-up (T1); (2) assess the association between the values of echocardiographic parameters at T1 and the expression profile of miR-30b-5p at T0. Thirty-five Cavalier King Charles Spaniels (median age 4.29 years and median weight 9 Kg) in different ACVIM stages were included (7 A, 19 B1, 6 B2 and 3 C). Inverse probability weighting analysis was performed to estimate the association of the exposure variable (miR-30b-5p) with the outcome variables (clinical and echocardiographic variables). Time was included as variable. The results pointed out that high levels of plasma miR-30b-5p corresponded to lower values of left ventricular end-diastolic diameter normalized for body weight, end-diastolic and end-systolic volumes indexed for body weight, and left atrium-to aortic root ratio. Hence, higher miR-30b-5p expressions were associated with milder forms of mitral valve disease in our study population. In contrast, the results obtained for the intensity of heart murmur, the mitral regurgitation severity, and the Mitral INsufficiency Echocardiographic score) were not statistically significant. A relationship between high abundance of miR-30b-5p and myxomatous mitral valve disease that appear echocardiographically more stable over time has been demonstrated. In conclusion, Cavalier King Charles Spaniels affected by myxomatous mitral valve disease that at the first cardiologic evaluation showed an upregulation of miR-30b-5p are expected to experience lesser variations on their echocardiographic examination between T0 and T1.

Prevalence and prognostic role of L wave and selected clinical and echocardiographic variables in dogs with atrial fibrillation

BACKGROUND

Information regarding the frequency of L waves and their prognostic relevance in dogs with secondary atrial fibrillation (AF) is limited.

HYPOTHESIS/OBJECTIVES

To determine whether L waves occur and ascertain their prognostic role, as well as the role of other clinical and echocardiographic variables in dogs with AF.

ANIMALS

Fifty-five dogs with AF associated with myxomatous mitral valve disease or dilated cardiomyopathy.

METHODS

Retrospective, multicenter observational study. In addition to L waves analysis, other clinical and echocardiographic variables, including type of antiarrhythmic treatment, were evaluated. A survival analysis was performed to test for predictors of cardiac death and all-cause mortality using Cox proportional hazards regression models.

RESULTS

L waves were evident in 33/55 dogs (60%, 95% confidence interval [CI] = 47%-72%) but their presence did not influence outcome. Increased left ventricular end-systolic diameter normalized for body weight (LVSDn) was a significant predictor of both cardiac death (hazard ratio [HR] = 4.41, 95% CI = 1.18-16.54; P = .03) and all-cause mortality (HR = 9.39, 95% CI = 2.49-35.32; P < .001). Heart rate assessed during echocardiography (Echo-HR) represented an additional significant predictor of cardiac death (HR = 1.01, 95% CI = 1.00-1.01; P = .04) and all-cause mortality (HR = 1.01, 95% CI = 1.00-1.01; P = .04).

CONCLUSIONS AND CLINICAL IMPORTANCE

L waves occurred frequently in dogs with AF, but held no prognostic relevance. Conversely, LVSDn and Echo-HR represented independent predictors of negative outcome in these animals.

Vagally Associated Second Degree Atrio-Ventricular Block in a Dog with Severe Azotemia and Evidence of Sympathetic Overdrive

A 14 years old, 6 kg, mix-breed male dog with severe azotemia due to urinary bladder herniation was presented to our Veterinary Teaching Hospital (VTH). Electrocardiography revealed normal heart rate of 100 bpm, evidence of sinus respiratory arrhythmia (SRA) and frequent second degree atrio-ventricular block following peak inspiratory phase suggestive of vagally-induced atrio-ventricular conduction delay. Echocardiographic examination showed mild mitral regurgitation without any other cardiac changes, and systolic (SAP) and diastolic (DAP) blood pressure values were 185/90 mmHg (SAP/DAP). Cardiac troponin I (cTnI) was increased to 7.3 ng/mL, suggesting a myocardial injury. A Holter examination revealed evidence of overall decrease in heart rate variability with evidence of sympathetic overdrive on time and frequency domain as well as when the non-linear Poincaré plot was analyzed. Based on the author's knowledge, this is the first report of a second degree atrio-ventricular block associated with vagal activity in a dog, with evidence of sympathetic overdrive and severe azotemia.

Echocardiographic parameters in 50 healthy English bulldogs: preliminary reference intervals

INTRODUCTION/OBJECTIVES

The objective of the study was to provide echocardiographic reference intervals for English bulldogs (EBs) and to assess if age, sex, body weight (BW), and heart rate have an influence on echocardiographic variables.

ANIMALS

We prospectively enrolled client-owned EBs that were considered healthy based on unremarkable history, normal physical examination, six-lead electrocardiography, and transthoracic echocardiography.

MATERIALS AND METHODS

Breed-related reference intervals were provided, and associations between age, sex, BW, and heart rate and echocardiographic variables were tested using a multivariate analysis. Allometric scales were generated for echocardiographic variables showing correlation with BW. Moreover, echocardiographic variables obtained in our population of EBs and previous published reference ranges were compared.

RESULTS

Echocardiographic reference intervals were generated from 50 healthy adult EBs. As per the multivariate analysis, left atrial diameter (p = 0.015), left ventricular internal end diastolic diameter (p = 0.002), aortic valve annulus (p = 0.032), and pulmonary valve annulus (p = 0.017) resulted influenced by BW, and reference intervals were generated using allometric scales. Our study suggests that EBs tend to have a smaller aortic root and sphericity index than other breeds. In addition, EBs seem to have smaller indexed left ventricular volumes and higher left ventricular ejection fraction than boxers and Doberman.

CONCLUSION

Preliminary reference intervals in the EBs are reported, which might be helpful for accurate echocardiographic interpretation and screening purposes in this breed.

Two radiographic methods for assessing left atrial enlargement and cardiac remodeling in dogs with myxomatous mitral valve disease

INTRODUCTION

Two radiographic measures of the left atrial (LA) size, the vertebral left atrial size (VLAS) and the radiographic left atrial dimension (RLAD), have been described in dogs. The aim of this study was to determine their feasibility and diagnostic value in the prediction of LA enlargement and clinical stage in dogs with myxomatous mitral valve disease (MMVD).

ANIMALS

111 client-owned dogs affected by MMVD.

METHODS

Retrospective study. In each dog, VLAS, RLAD, vertebral heart score (VHS), and left atrium-to-aorta-ratio (LA/Ao) were measured. The correlation between VLAS, RLAD, and LA/Ao was evaluated. The diagnostic accuracy of VLAS and RLAD was assessed for the detection of LA enlargement and clinical staging using the receiver operating characteristic curve analysis.

RESULTS

A positive correlation was observed between VLAS, RLAS, and LA/Ao (r = 0.816 and r = 0.855, respectively; p<0.0001). Both VLAS (area under the curve [AUC], 0.93; p<0.0001) and RLAD (AUC, 0.98; p<0.0001) showed high diagnostic accuracy in the detection of LA enlargement. In the stage B, the RLAD (AUC, 0.99; cutoff, ≥1.8; sensitivity, 100%; specificity 93%) performed better than VLAS (AUC, 0.90; cutoff, ≥2.4; sensitivity, 66%; specificity 100%) and VHS (AUC, 0.89; cutoff, ≥10.7; sensitivity, 88%; specificity 83%) in the detection of dogs fulfilling the echocardiographic criteria for stage B2.

CONCLUSIONS

VLAS and RLAD represent useful radiological tools for the detection of LA enlargement in dogs with MMVD. In asymptomatic dogs, the RLAD performs better than VLAS and VHS in the prediction of those fulfilling the echocardiographic criteria for stage B2.

Comparative assessment of left atrial volume in healthy cats by two-dimensional and three-dimensional echocardiography

Background

The left atrium (LA) is an important prognostic parameter in cardiac pathologies of cats. Its size is currently measured in one-dimensional methods, while human medicine considers two- and three-dimensional echocardiography as standard. The objectives of this study were to compare monoplane, biplane, triplane and real-time three dimensional echocardiography for volumetric measurement of the left atrium in healthy cats and establish a reference interval for further studies on cats with heart disease. Additionally, the influence of age, sex and weight on left atrial volume (LAV) was tested.

Results

One dimensional monoplane Simpson method of discs (SMOD) in the right parasternal four chamber view (r4) and the left apical 2 chamber view (l2) as well as biplane SMOD had no significant difference for left atrial maximum volume (LAMax). They can be used as equivalent in future studies and one common reference range was set up (1.96 ± 0.54 ml). Those three methods produced significantly higher volumes than triplane echocardiography (RTTPE) and real time three dimensional echocardiography (RT3DE) using TomTec® software. LA volumetry with RTTPE and RT3DE-TomTec™ was more feasible than expected, but low RT3DE image quality was the main reason for excluding patients. Neither age nor weight had an influence on LA volume in healthy cats. Male LAV results were only slightly, but in 2D and RTTPE significantly higher than those of female cats with a range of + 10.46% to + 19.58%.

Conclusions

Monoplane, biplane, triplane and real-time three dimensional echocardiography were feasible for LA volumetry in healthy cats and showed acceptable intra- and interobserver variability. One common LAMax reference range for monoplane r4, l2 and biplane SMOD was set up. Raw data can be used for LA volumes and does not need to be correlated with the cat’s weight or age. Male cats have only slightly but significantly larger atria than females in 2D and RTTPE. Therefore, under reservation, also sex related limit values were defined.

Reproducibility of echocardiographic indices of left atrial size in dogs with subclinical myxomatous mitral valve disease

Background

Reliability of echocardiographic measurements of left atrial (LA) size, an important marker of disease severity, has not been reported in dogs with myxomatous mitral valve disease (MMVD).

Objectives

To define and compare reliability of left atrial dimension/diameter (LAD), LAD indexed to aortic valve diameter (LAD/AoD), left atrium‐to‐aortic root ratio (LA/Ao), left atrial volume acquired from a right parasternal long‐axis (LAV^RPLx), and left apical view (LAV^LAP) in dogs with subclinical MMVD.

Animals

Nine dogs with subclinical MMVD.

Methods

Prospective reproducibility study. Dogs underwent 12 echocardiographic examinations by 2 operators on the mornings and afternoons of 3 nonconsecutive days within 1 week. Reliability (measurement variability) was quantified using coefficients of variation (CV) and 95% repeatability/reproducibility coefficients (95% RC). A mixed‐model analysis of variance (ANOVA) was used to determine if time of day, day, and operator were significant sources of variability for each index.

Results

Linear measurements (LAD, LAD/AoD, and LA/Ao) exhibited less within‐day, between‐day, and interoperator variability (CVs, 3.9%‐12.5%) than did volume estimate measurements (LAV^RPLx and LAV^LAP; CVs, 11.8%‐17.9%). Of the linear measurements, LA/Ao exhibited greater variability (CVs, 9.9%‐12.5%) compared to LAD and LAD/AoD (CVs, 3.9%‐4.9%). Operator was a significant (P = .005) source of variability for LA/Ao.

Conclusions and Clinical Importance

Compared to other linear measurements, LA/Ao was the least reproducible and most dependent on operator. The 95% RC for each LA size index are provided to help identify clinically relevant changes (beyond intraoperator or interoperator variability) during serial echocardiographic examinations of dogs with subclinical MMVD.