Transvalvular pulmonic stent angioplasty: procedural outcomes and complications in 15 dogs with pulmonic stenosis.

INTRODUCTION: Balloon valvuloplasty is the treatment of choice for dogs with severe type A pulmonic stenosis (PS), but less successful for dogs with annular hypoplasia and unsuitable for supravalvular stenosis or cases with a circumpulmonary coronary malformation. We report outcomes and complications of the first 15 consecutive transvalvular pulmonic stent angioplasty procedures performed by a single center in dogs with PS. ANIMALS: Fifteen dogs with naturally occurring PS were included in the study. MATERIALS AND METHODS: Dogs underwent echocardiography before and four weeks after the procedure. Transvenous approaches were used to deploy a pre-mounted, balloon-expandable metallic stent in all cases. RESULTS: Of 15 dogs, all had annular hypoplasia, and in addition, supravalvular stenosis was diagnosed in 11 of 15 dogs, and three had R2A coronary malformation. All dogs survived to discharge. One dog died less than four weeks postoperatively (non-cardiac), but 14 of 15 dogs were re-examined at four weeks. Severity reduced in all cases; median pressure gradient reduced from 137 mmHg (range 81-202 mmHg) to 83 mmHg (range 31-155 mmHg). Clinical signs improved in all cases, and hematocrit reduced in all dogs with erythrocytosis. The median follow-up time was 280 days (range 95-896 days). Over one-year follow-up was available in six of fifteen dogs. Two dogs died because of refractory right-sided congestive heart failure signs: one at 10 months and one at 22 months postoperatively. CONCLUSIONS: Transvalvular pulmonic stent angioplasty technique was associated with an improvement in clinical signs and reduction in stenosis severity for all dogs in this population, including cases with supravalvular PS or circumpulmonary coronary malformation.

Long-term biological variability and the generation of a new reference interval for plasma N-terminal pro-B-type natriuretic peptide in Labrador retrievers.

OBJECTIVES: First, to investigate the biological variability of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in healthy Labrador retrievers and compare this with current laboratory recommendations for dilated cardiomyopathy screening. Second, to calculate a breed-specific reference interval and validate it in a retrospective cohort. MATERIALS AND METHODS: Plasma NT-proBNP was measured in 51 clinically healthy Labrador retrievers at 0, 2, 4, 6 and 8 weeks. Coefficient of variation for individual dogs over time, the coefficient of variation for the group at each time point and the index of individuality were calculated. A reference interval was derived and tested on a clinical dataset available from four UK cardiology referral centres. RESULTS: Median NT-proBNP was 865 pmol/L (315 to 2064 pmol/L). Mean individual coefficient of variation was 19% (95% CI: 16 to 21%) and group coefficient of variation was 43% (95% CI: 41 to 46%), with index of individuality at 0.44. The breed-specific reference interval was 275 to 2100 pmol/L. In the validation group, 93% of NT-proBNP measurements from healthy dogs were within the reference interval. NT-proBNP measurements exceeded the reference interval in 82% of dogs with dilated cardiomyopathy. The upper bound of the reference interval (2100 pmol/L) had a positive predictive value of 90% and a negative predictive value of 87% for identification of dilated cardiomyopathy in this population. CLINICAL SIGNIFICANCE: Breed-specific reference intervals might improve the diagnostic accuracy of NT-proBNP measurement. Applying the currently recommended general cut-off value to Labradors is likely to result in frequent false positives and diagnosis would be improved by application of the new breed-specific reference interval calculated here.

Diagnostic value of the pulmonary vein-to-right pulmonary artery ratio in dogs with pulmonary hypertension of precapillary origin.

INTRODUCTION: Non-invasive diagnosis of pulmonary hypertension (PH) relies on estimation of pulmonary arterial pressure (PAP) via Doppler echocardiographic measurement of tricuspid regurgitation pressure gradient (TRPG). The pulmonary vein-to-right pulmonary artery ratio (PV/PA) recently has been described for the detection of pulmonary venous congestion. Whether this variable could be used to detect the presence of precapillary PH is unknown. The objective of the present study was to investigate the diagnostic value of PV/PA for prediction of TRPG, as a surrogate of PAP, in dogs with PH of precapillary origin. ANIMALS: Sixty-seven client-owned dogs were included in the study. METHODS: This was a retrospective study. Dogs with a measurable TRPG were included and classified into group 1 (TRPG < 30 mmHg), group 2 (TRPG 30-49 mmHg), group 3 (TRPG 50-80 mmHg), or group 4 (TRPG > 80 mmHg). The PV/PA, acceleration time-to-ejection time ratio of pulmonary artery flow, main pulmonary artery diameter-to-aortic diameter ratio, and right pulmonary artery distensibility index were measured retrospectively from cineloops in each dog. RESULTS: The PV/PA measured by both two-dimensional (2D) and time-motion mode(MM) echocardiography decreased proportionally with PH severity. Using regression analysis, PV/PA (2D) was identified as the strongest predictor for TRPG (R2 = 0.70, p < 0.0001) among other variables studied, with a good diagnostic accuracy (area under the curve = 0.94) for moderate PH (TRPG > 50 mmHg) using a cutoff value of < 0.70 (sensitivity = 96%, specificity = 82%). CONCLUSIONS: Results of the present study suggest that PV/PA can be useful as an additional, non-invasive, and indirect variable to identify precapillary PH in dogs.

Pulmonary Vein-to-Pulmonary Artery Ratio is an Echocardiographic Index of Congestive Heart Failure in Dogs with Degenerative Mitral Valve Disease.

BACKGROUND: Early recognition of left-sided congestive heart failure (CHF) in dogs with degenerative mitral valve disease (DMVD) is important because it influences medical therapy, timing of follow-up, and outcome. HYPOTHESIS: Pulmonary vein diameter-to-pulmonary artery diameter ratio (PV/PA) measured by echocardiography can predict CHF. ANIMALS: Ninety-eight client-owned dogs, 37 controls, and 61 dogs with DMVD. METHODS: Prospective clinical cohort study. History, physical examination and Doppler-echocardiography were performed. Dogs were classified as International Small Animal Cardiac Health Council class I, II or III. Congestive heart failure was identified in a subset of 56 dogs based on radiographic findings. The PV/PA was measured in bidimensional (2D) and M-mode by 2 investigators blinded to the radiologists' conclusions. RESULTS: Interobserver coefficients of variation for PV/PA acquisition and measurement were <10%. The PV/PA in control dogs was approximately 1 and increased with class of heart failure. The presence of CHF could be best predicted by measuring PV/PA in 2D echocardiography (cut-off, 1.7; area under the curve, 0.98; CI, 0.97-0.98; P < .001) with a sensitivity of 96% and a specificity of 91%. CONCLUSION AND CLINICAL IMPORTANCE: The PV/PA is a simple and reproducible echocardiographic variable that increases with class of heart failure and may help discriminate dogs in CHF from asymptomatic dogs with DMVD. Additional studies are required to determine whether PV/PA might provide additional information in the integrated interpretation of Doppler-echocardiographic indices of left ventricular filling pressures and could be used for rapid assessment of CHF in dogs in a critical care setting.

Effect of physiological determinants and cardiac disease on plasma adiponectin concentrations in dogs.

BACKGROUND: In humans, a high concentration of adiponectin is associated with a favorable cardiovascular risk profile whereas, in patients with heart failure (HF), a high concentration of adiponectin is associated with a less favorable prognosis. HYPOTHESIS/OBJECTIVES: To evaluate the physiological determinants of plasma adiponectin concentration in dogs and the influence of heart disease, myxomatous mitral valve disease (MMVD), and dilated cardiomyopathy (DCM). ANIMALS: One hundred and fourteen client-owned dogs and 9 Beagles from the research colony of the Clinical Veterinary Unit of the University of Liège. METHODS: We prospectively measured circulating adiponectin concentration in healthy control dogs (n = 77), dogs with MMVD (n = 22) and dogs with DCM (n = 15) of various degrees of severity. Diagnosis was confirmed by Doppler echocardiography. Plasma adiponectin concentration was measured by a canine-specific sandwich ELISA kit. RESULTS: An analysis of covariance showed an association between adiponectin concentration and age, neuter status, and heart disease. No association between adiponectin concentration and class of HF, sex, body condition score, body weight, circadian rhythm, or feeding was found. Plasma adiponectin concentration was negatively correlated with age (P = .001). Adiponectin was lower in neutered (P = .008) compared to intact dogs. Circulating adiponectin concentration was increased in dogs with DCM compared to healthy dogs (P = .018) and to dogs with MMVD (P = .014). CONCLUSIONS AND CLINICAL IMPORTANCE: Age and neutering negatively influence circulating adiponectin concentration. Plasma adiponectin concentration increased in dogs with DCM. Additional research is required to investigate if this hormone is implicated in the pathophysiology of DCM and associated with clinical outcome.