Echocardiographic reference intervals for right ventricular indices, including 3-dimensional volume and 2-dimensional strain measurements in healthy dogs

Assessment of right ventricular function in healthy Great Danes and in Great Danes with dilated cardiomyopathy

INTRODUCTION

Right ventricular (RV) dysfunction is a significant negative prognostic indicator in human dilated cardiomyopathy (DCM). Many RV indices are weight-dependent, and there is a lack of reference values for the right heart in giant breed dogs (over 50 kg), including Great Danes (GDs). This study aimed to compare indices of RV function in echocardiographically normal GDs, those with preclinical DCM (PC-DCM), and those with DCM and congestive heart failure (DCM-CHF).

ANIMALS

A total of 116 client-owned adult GDs: 74 normal, 31 with PC-DCM, and 11 with DCM-CHF.

METHODS

A retrospective, single-center cohort study assessed RV function using free-wall RV longitudinal strain (RVLS), strain rate, fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), and pulsed-wave tissue Doppler imaging-derived systolic myocardial velocity of the lateral tricuspid annulus (TDI S'). Relationships between DCM status and RV function indices were analyzed.

RESULTS

RV function, measured by TAPSE (P=0.001), FAC (P<0.001), and TDI S' (P<0.001), decreased in dogs with PC-DCM and DCM-CHF compared to healthy dogs, with FAC being lower in DCM-CHF compared to PC-DCM (P=0.048). RVLS impairment was more significant in the DCM-CHF group than in the PC-DCM group (P=0.048). RVLS had the highest area under the curve (0.899) for differentiating between normal and DCM-CHF dogs.

CONCLUSION

As DCM progresses, echocardiographic variables of RV function, including TAPSE, FAC, TDI S', RVLS, and strain rate, worsen, indicating impaired RV systolic function in GDs affected by DCM.

Right Ventricle Strain Assessed by 2-Dimensional Speckle Tracking Echocardiography (2D-STE) to Evaluate Pulmonary Hypertension in Dogs with Dirofilaria immitis

Echocardiographic assessment of the right ventricle is helpful for analysing the pathophysiology of heartworm disease and detecting pulmonary hypertension (PH) in dogs. In veterinary cardiology, the study of myocardial deformation using two-dimensional speckle tracking (2D-STE) echocardiography has become increasingly acknowledged as useful for quantifying right ventricular function. The aim of this study was to evaluate the usefulness of myocardial deformation strain of the right ventricular free wall (FWS), global deformation strain of the right ventricle, including the interventricular septum (GS), and tissue motion annular displacement of the tricuspid valve (TMAD) in a cohort of dogs with heartworm (Dirofilaria immitis) disease and to determine cut-off values for detecting the presence of PH. Out of the 93 dogs tested, 71% were diagnosed with heartworm infection. PH was identified in 41% of the infected dogs following the American College of Veterinary Internal Medicine (ACVIM) guidelines, based on the peak tricuspid regurgitation velocity to calculate the tricuspid regurgitation pressure gradient (TRPG), while other routine measurements were used, including the right pulmonary artery distensibility index (RPADi). The 2D-STE mode measurements were determined using Right Ventricular Automated Function Imaging (RV AFI®) software. The statistical analysis showed significant differences in the studied parameters among dogs with and without PH. Additionally, sensitivity (sen) and specificity (sp) cut-off values were obtained (GS ≥ -21.25%, sen 96%, sp 86.4%; FWS ≥ -21.95%, sen 92.56%, sp 95.5%; TMAD ≤ 0.85 cm, sen 70.4%, sp 83.3%). These results demonstrated that GS, FWS, and TMAD could be used as supplementary and alternative variables to conventional echocardiographic measurements when detecting PH in dogs with heartworm disease.

Current use of real-time three-dimensional transthoracic echocardiography in animals

This review includes 36 studies of transthoracic real-time three-dimensional echocardiography (RT3DE) in animals. Most of these studies concern cardiac chamber quantification of the left atrium and left ventricle, in dogs. Comparisons of RT3DE and different two-dimensional echocardiographic (2DE) methods have been reported in dogs with myxomatous mitral valve disease (MMVD), dilated cardiomyopathy, and in healthy control dogs. Comparisons of RT3DE and standard reference methods have been reported in healthy control dogs. In dogs with MMVD, volumetric RT3DE measurements of left atrium do not appear to provide superior prognostic value compared with 2DE methods using Simpson's method of discs in dogs with MMVD. The major advantages of RT3DE compared to 2DE include improvements in visualization of the complex morphology of the mitral valve, the estimation of mitral valve regurgitation, and improved visualization of complex congenital cardiac abnormalities.

Un cas de situs inversus complet associé à une communication interventriculaire et des anomalies oculaires chez une chienne croisée de 3 ans

A case of complete situs inversus associated with an interventricular communication and ocular abnormalities in a 3-year-old mixed-breed female dog. A 3-year-old female dog was referred for exploration of a murmur concomitant with lethargy. An echocardiogram reveals an inversion of the position of the cardiac chambers and the presence of an interventricular communication. A computed tomography examination of the thorax and abdomen highlights the known cardiac abnormalities as well as the association of a complete situs inversus. The clinical examination also reveals ocular malformations (deviation of the eyeballs and asymmetry of the fundus). This article highlights the variety of abnormalities that can be associated with the complete inversion of the organs and demonstrates that there may be variants to the more classic picture usually encountered in humans (respiratory manifestations related to Kartagener syndrome).(Translated by Dr Serge Messier).

N-terminal brain natriuretic peptide, cardiac troponin-I, and point-of-care ultrasound in dogs with cardiac and noncardiac causes of nonhemorrhagic ascites

BACKGROUND

Nonhemorrhagic ascites (NHA) can be caused by cardiac diseases (cNHA) and noncardiac diseases (ncNHA). N-terminal brain natriuretic peptide (NT-proBNP), cardiac troponin-I (cTnI), and point-of-care ultrasound (POCUS) may differentiate between cNHA and ncNHA.

HYPOTHESIS/OBJECTIVES

We compared NT-proBNP and cTnI concentrations as well as POCUS findings in dogs presented with cNHA and ncNHA.

ANIMALS

Dogs (n = 60) were enrolled based on identification of NHA with an effusion packed cell volume < 10%.

METHODS

Blood samples were collected and POCUS was performed on all dogs. Dogs were diagnosed with cNHA (n = 28) or ncNHA (n = 32) based on echocardiography. The cNHA group was subdivided into cardiac non-pericardial disease (n = 17) and pericardial disease (n = 11).

RESULTS

The NT-proBNP concentration (median; range pmol/L) was significantly higher in the cNHA group (4510; 250-10 000) compared to the ncNHA group (739.5; 250-10 000; P = .01), with a sensitivity of 53.8% and specificity of 85.7% using a cut-off of 4092 pmol/L. The NT-proBNP concentrations were significantly higher in the cardiac non-pericardial disease group (8339; 282-10 000) compared with the pericardial disease group (692.5; 250-4928; P = .002). A significant difference in cTnI concentration (median; range ng/L) between the cNHA group (300; 23-112 612) and ncNHA group (181; 17-37 549) was not detected (P = .41). A significantly higher number of dogs had hepatic venous and caudal vena cava distension in the cNHA group compared to the ncNHA group, respectively (18/28 vs 3/29, P < .0001 and 13/27 vs 2/29, P < .001). Gall bladder wall edema was not significantly different between groups (4/28 vs 3/29, P = .74).

CONCLUSIONS AND CLINICAL IMPORTANCE

NT-proBNP concentration and POCUS help distinguish between cNHA and ncNHA.

Right ventricular size and function evaluated by various echocardiographic indices in dogs with pulmonary hypertension

BACKGROUND

Three-dimensional (3D) echocardiography and 2-dimensional (2D) strain measurements of the right ventricle (RV) are important indices in humans with pulmonary hypertension (PH) and need further evaluation in dogs with PH.

OBJECTIVES

To evaluate various RV size and function indices in dogs with PH and to examine differences between pre- and postcapillary PH.

ANIMALS

A total of 311 client-owned dogs: 100 dogs with PH, 31 with postcapillary and 69 with precapillary PH, and 211 healthy control dogs.

METHODS

Retro- and prospective, multicenter study. Size and function of the RV was determined using several indices, derived using dedicated RV software, including 3D RV end-diastolic volume (EDVn), end-systolic volume (ESVn), ejection fraction, 2D global and free wall RV longitudinal strain (RVLS), end-diastolic area, end-systolic area, fractional area change, tricuspid annular plane systolic excursion, and tissue Doppler imaging-derived systolic myocardial velocity of the lateral tricuspid annulus (S'n).

RESULTS

The EDVn (1.8 vs 2.5 mL/kg^0.942 , P < .01) and ESVn (0.8 vs 1.2 mL/kg^0.962 , P < .001) were significantly larger in the PH group compared to healthy controls. Free wall RVLS was decreased in dogs with severe PH compared to controls (-24% vs -29.6%, P < .001). Dogs with precapillary PH had worse RV systolic function than dogs with postcapillary PH.

CONCLUSION

Three-dimensional echocardiography of the RV is a promising tool to detect RV changes in dogs with PH. Also, 2D strain measurements are able to detect decreased RV function and offer several advantages compared to conventional indices.

Evaluation of a Novel Precordial Lead System for the Electrocardiographic Diagnosis of Right Ventricular Enlargement in Dogs

The purpose of this study was to evaluate the reliability of precordial leads for the detection of right ventricular enlargement (RVE) in dogs. This was a prospective observational study. The RVE was defined by echocardiography. The amplitude (mV) of the Q, R, and S waves, the R/S ratio, and the mean electrical axis (MEA) of the QRS complex were assessed on the 12-lead ECG. The ROC curve and the Youden index yielded the best cutoffs for RVE detection. An area under the curve (AUC) > 0.7 defined suitable diagnostic accuracy. A total of 84 dogs, 27 with RVE and 57 healthy controls, were enrolled. Q wave amplitude in aVR (cutoff > 0.10 mV; AUC = 0.727), R/S ratio in V4 (cutoff < 1.15; AUC = 0.842), R/S ratio in V5 (cutoff < 1.95; AUC = 0.839) and S wave amplitude in V6 (cutoff > 0.70 mV; AUC = 0.703) showed suitable diagnostic accuracy in detecting RVE. Among dogs with RVE, only 9/27 (33%) presented a right shift of MEA. Differently, 19/27 (70%) showed at least one of the identified precordial lead criteria. Assessment of the R/S ratio in V4 and V5 and S wave amplitude in V6 increases the diagnostic accuracy of ECG in distinguishing between dogs with RVE and healthy dogs.

Investigation of Beraprost Sodium on Cardiac Function and Hemodynamics in Canine Models of Chronic Pulmonary Hypertension

Pulmonary hypertension (PH) is a life-threatening disease in dogs characterized by increased pulmonary arterial pressure (PAP) and/or pulmonary vascular resistance. No study has evaluated the utility of Beraprost sodium (BPS) in dogs with PH. This study aimed to evaluate the effect of BPS on cardiac function and hemodynamics and examine the optimal dose of BPS in canine models of chronic embolic PH. In this prospective crossover study, three doses of BPS (5, 15, and 25 μg/kg, twice a day) were examined in eight canine models of chronic embolic PH. All model dogs underwent invasive PAP measurement, echocardiography, and non-invasive systemic blood pressure measurement before and after continuous administration of oral BPS for 1 week. No side effects of BPS were observed in any dog during the study. All doses of BPS significantly decreased systolic PAP and pulmonary vascular impedance. Additionally, systemic vascular impedance significantly decreased with 15 and 25 μg/kg of BPS. The right ventricular stroke volume and longitudinal strain significantly decreased with all doses of BPS. The left ventricular stroke volume and circumferential strain decreased with 15 μg/kg BPS. BPS was well-tolerated in this study. A dose-dependent vasodilating effect on pulmonary vessels was observed in canine models of chronic PH. Additionally, 15 μg/kg BPS showed a balanced vasodilating effect on systemic and pulmonary vessels. Furthermore, with a decrease in systemic and pulmonary vascular impedance, the left and right ventricular functions were significantly improved. Our results suggest that BPS may be useful in the treatment of canine PH.

Case Report: Tricuspid Annuloplasty for Right-Sided Congestive Heart Failure Secondary to Pulmonary Hypertension in a Dog

An 11-year-old, 12.3-kg, female Miniature Dachshund was presented to our institution with ascites of unknown etiology. The dog had been administered moxidectin for 3 years to treat a heartworm infection. Thoracic radiographs showed enlargement of the right heart. Echocardiography revealed right atrial and ventricular dilatation as well as flattening of the interventricular septum. Heartworm was identified in the main pulmonary artery, which was dilated. Tricuspid regurgitation (TR) was observed using color Doppler ultrasonography, and 2.5 L of ascites were removed. The dog was diagnosed with pulmonary hypertension, severe TR, and right-sided congestive heart failure. Except at the initial site, heartworm was not detected using echocardiography, and the antigen test was negative. However, pharmacological treatment did not improve the right-sided congestive heart failure. Instead, De Vega tricuspid annuloplasty (TAP) was performed on the beating heart under cardiopulmonary bypass with the owner's consent. Sutures terminated between the two commissures in the middle of the annulus and were secured using another pledget. Annular reduction was performed by tying down the plication suture while the cylindrical sizer was inserted into the tricuspid valve orifice. The size of the cylindrical sizer was 16 mm, which was set based on the height and width of the septal leaflet. A 6-month follow-up showed a reduction of TR and right-sided volume overload with no evidence of ascites retention/recurrence or any other complication. Our findings indicate that TAP may be a valid treatment option for dogs with right-sided congestive heart failure caused by secondary TR.