Anterior mitral valve leaflet length in cats with hypertrophic cardiomyopathy.

INTRODUCTION: Anterior mitral valve leaflet (AMVL) elongation is a recognised feature of hypertrophic cardiomyopathy (HCM). However, whether AMVL elongation precedes left ventricular hypertrophy in cats is currently unknown. The aim of this study was to explore the risk of developing an HCM phenotype in cats with an elongated AMVL. ANIMALS: FIFTY-FIVE APPARENTLY HEALTHY CATS WITH A NORMAL BASELINE ECHOCARDIOGRAM AND A FOLLOW-UP ECHOCARDIOGRAM AT >ONE YEAR. MATERIALS AND METHODS: This was a retrospective longitudinal study. Cats at the baseline were grouped based on whether or not they developed an HCM phenotype at follow-up. AMVL length and left atrial and left ventricular dimensions were measured from two-dimensional images. RESULTS: The median follow-up period of the study population was 5.4 years (25th and 75th quartile, 2.7-6.7 years). During this time, 17 cats (30.9%) developed an HCM phenotype. At the baseline, cats that subsequently developed an HCM phenotype had greater AMVL length (9.4 mm [25th and 75th quartile, 9.0-10.6 mm] vs. 8.5 mm [25th and 75th quartile, 7.6-9.1 mm], P < 0.0001) and maximal left ventricular wall thickness (4.5 mm [25th and 75th quartile, 4.1-4.7 mm] vs. 4.0 mm [25th and 75th quartile, 3.7-4.6 mm], P = 0.007) than those that did not. Multiple logistic regression analysis confirmed that both baseline variables were independent predictors for development of an HCM phenotype. CONCLUSIONS: The AMVL length was greater in cats that subsequently developed left ventricular hypertrophy. Further studies investigating the clinical application of AMVL in the natural history of feline HCM are warranted.

Surgical valvulotomy for tricuspid valve stenosis in a dog.

A 2-year, 4-month-old neutered female Labrador retriever was brought for evaluation of right-sided congestive heart failure. Echocardiographic examination revealed tricuspid valve dysplasia with only two small orifices in the valve resulting in severe tricuspid stenosis. The dog underwent a right fifth lateral intercostal thoracotomy and surgical tricuspid valvulotomy, under cardiopulmonary bypass. The stenosis was relieved by dividing the valve leaflets between the two orifices with continuation to the commissures, creating a 'bileaflet' valve. The dog made a good recovery initially, with echocardiography at 48 h after surgery showing a reduction in tricuspid valve E and A wave velocities and pressure half-time (from 230 ms to 65 ms). She was discharged five days after surgery, and spironolactone, benazepril, pimobendan, and clopidogrel were prescribed. The dog was re-presented two days later having collapsed, with pyrexia, facial swelling, and pitting edema on the ventral neck and intermandibular region. Investigations did not reveal an underlying cause, and the clinical signs resolved with supportive therapy. Two years after surgery, the dog was free of clinical signs with normal exercise tolerance and only mild tricuspid regurgitation on echocardiography, with discontinuation of all medications.

Mitral Annular Plane Systolic Excursion and Tricuspid Annular Plane Systolic Excursion in Cats with Hypertrophic Cardiomyopathy.

BACKGROUND: Left ventricular (LV) systolic dysfunction is associated with increased risk of death in cats with hypertrophic cardiomyopathy (HCM). Mitral and tricuspid annular plane systolic excursion (MAPSE and TAPSE, respectively) are measures of longitudinal systolic function and are reduced in human patients with HCM. HYPOTHESES: Cats with HCM have lower MAPSE and TAPSE compared to control cats; lower MAPSE and TAPSE are associated with the presence of congestive heart failure (CHF) and reduced survival time. ANIMALS: 64 cats with HCM and 27 healthy cats. Forty-five cats with HCM were not showing clinical signs, and 19 had CHF. METHODS: Retrospective study. Anatomic M-mode from the left apical 4-chamber view was used to record MAPSE from the free wall (MAPSE FW) and septum (MAPSE IVS) and TAPSE. RESULTS: Compared to controls, cats with HCM had lower MAPSE IVS (controls 5.2 [4.6-5.6] mm, asymptomatic HCM 4.7 [4.1-5.2] mm, HCM with CHF 2.6 [2.5-3.2] mm, P < .001), MAPSE FW (controls 5.9 [5.3-6.2] mm, asymptomatic HCM 4.7 [4.1-5.1] mm, HCM with CHF 2.8 [2.4-3.2] mm) and TAPSE (controls 8.6 [7.4-10.2] mm, asymptomatic HCM 7.2 [6.3-8.2] mm, HCM with CHF 4.6 [4.1-5.4] mm), with the lowest in the CHF group. Univariate survival analysis showed a shorter survival in cats displaying lower MAPSE IVS, MAPSE FW, and TAPSE. CONCLUSIONS AND CLINICAL IMPORTANCE: MAPSE and TAPSE were lower in cats with HCM than in control cats and were lowest in CHF, suggesting that systolic longitudinal dysfunction is present in cats with HCM. MAPSE and TAPSE have potential prognostic significance.

Assessment of mitral regurgitation in dogs: comparison of results of echocardiography with magnetic resonance imaging.

OBJECTIVES: Echocardiography is used routinely to assess mitral regurgitation severity, but echocardiographic measures of mitral regurgitation in dogs have not been compared with other quantitative methods. The study aim was to compare echocardiographic measures of mitral regurgitation with cardiac magnetic resonance imaging-derived mitral regurgitant fraction in small-breed dogs. METHODS: Dogs with myxomatous mitral valve disease scheduled for magnetic resonance imaging assessment of neurological disease were recruited. Correlations were tested between cardiac magnetic resonance imaging-derived mitral regurgitant fraction and the following echocardiographic measures: vena contracta/aortic diameter, transmitral E-wave velocity, amplitude of mitral prolapse/aortic diameter, diastolic left ventricular diameter:aortic diameter, left atrium:aortic diameter, mitral regurgitation jet area ratio and regurgitant fraction calculated using the proximal isovelocity surface area method. RESULTS: Measurement of cardiac magnetic resonance imaging-derived mitral regurgitant fraction was attempted in 21 dogs. Twelve consecutive, complete studies were obtained and 10 dogs were included in the final analysis: vena contracta/aortic diameter (r = 0 · 89, p = 0 · 001) and E-wave velocity (r = 0 · 86, p = 0 · 001) had the strongest correlations with cardiac magnetic resonance imaging-derived mitral regurgitant fraction. E velocity had superior repeatability and could be measured in all dogs. The presence of multiple jets precluded vena contracta/aortic diameter measurement in one dog. CLINICAL SIGNIFICANCE: Measurement of cardiac magnetic resonance imaging-derived mitral regurgitant fraction is feasible but technically demanding. The echocardiographic measures that correlated most closely with cardiac magnetic resonance imaging-derived mitral regurgitant fraction were vena contracta/aortic diameter and E-wave velocity.

Cardiovascular-renal axis disorders in the domestic dog and cat: a veterinary consensus statement.

OBJECTIVES: There is a growing understanding of the complexity of interplay between renal and cardiovascular systems in both health and disease. The medical profession has adopted the term "cardiorenal syndrome" (CRS) to describe the pathophysiological relationship between the kidney and heart in disease. CRS has yet to be formally defined and described by the veterinary profession and its existence and importance in dogs and cats warrant investigation. The CRS Consensus Group, comprising nine veterinary cardiologists and seven nephrologists from Europe and North America, sought to achieve consensus around the definition, pathophysiology, diagnosis and management of dogs and cats with "cardiovascular-renal disorders" (CvRD). To this end, the Delphi formal methodology for defining/building consensus and defining guidelines was utilised. METHODS: Following a literature review, 13 candidate statements regarding CvRD in dogs and cats were tested for consensus, using a modified Delphi method. As a new area of interest, well-designed studies, specific to CRS/CvRD, are lacking, particularly in dogs and cats. Hence, while scientific justification of all the recommendations was sought and used when available, recommendations were largely reliant on theory, expert opinion, small clinical studies and extrapolation from data derived from other species. RESULTS: Of the 13 statements, 11 achieved consensus and 2 did not. The modified Delphi approach worked well to achieve consensus in an objective manner and to develop initial guidelines for CvRD. DISCUSSION: The resultant manuscript describes consensus statements for the definition, classification, diagnosis and management strategies for veterinary patients with CvRD, with an emphasis on the pathological interplay between the two organ systems. By formulating consensus statements regarding CvRD in veterinary medicine, the authors hope to stimulate interest in and advancement of the understanding and management of CvRD in dogs and cats. The use of a formalised method for consensus and guideline development should be considered for other topics in veterinary medicine.

Prognostic value of 24-hour ambulatory ECG (Holter) monitoring in Boxer dogs.

BACKGROUND: Boxer dogs are reported to be predisposed to arrhythmogenic right ventricular cardiomyopathy (ARVC), but the natural history has not been well characterized and inconsistent diagnostic criteria have been applied to identify affected dogs. Echocardiographic examination findings are unremarkable in many affected Boxer dogs, and in these dogs, 24-hour ambulatory ECG (Holter) monitoring often is used for diagnostic and prognostic purposes, despite limited information available relating Holter findings to outcome. HYPOTHESIS/OBJECTIVES: Boxers with complex ventricular arrhythmias at initial presentation will have shorter survival times. The objective was to investigate the prognostic value of Holter monitoring in Boxer dogs. ANIMALS: One hundred and twenty-two Boxer dogs seen at 3 university referral hospitals. METHODS: Retrospective study. Survival times were obtained for Boxer dogs evaluated by echocardiography and a 24-hour Holter ECG. Kaplan-Meier survival analysis was used to estimate the median survival time and Cox proportional hazards analysis was used to identify variables independently associated with cardiac mortality. RESULTS: Outcome data were obtained for 122/163 dogs meeting the inclusion criteria. Of the 70 dogs that had died, 45 were considered to have suffered cardiac-related deaths. Median survival was significantly longer in dogs with a left ventricular systolic diameter (LVIDs) ≤ 35 mm compared with those with LVIDs > 35 mm (P < .001). Multivariable analysis in dogs with LVIDs ≤ 35 mm showed that the presence of ventricular tachycardia, age >4.5 years, and male sex were independent predictors of cardiac mortality. CONCLUSIONS AND CLINICAL IMPORTANCE: Holter monitoring in Boxer dogs provides valuable prognostic information.

Circulating natriuretic peptides in cats with heart disease.

BACKGROUND: Circulating natriuretic peptide concentrations are increased in cats with myocardial dysfunction. HYPOTHESIS: Serum N-terminal fragment of proatrial natriuretic peptide (NT-proANP) and NT-probrain natriuretic peptide (proBNP) concentrations may predict the presence of heart disease (HD) and congestive heart failure (CHF). A positive relationship is also predicted among natriuretic peptide (NP) concentrations, a noninvasive estimate of left ventricular filling pressure (E/E(a)), and an echocardiographic measure of left atrial (LA) size (LA/aortic diameter [Ao]). METHODS: Serum NP concentrations were measured in 28 healthy control and 50 study cats using sandwich enzyme immunoassays. The study group comprised cats, with HD but no CHF (HD - CHF, n = 17) and cats with CHF (HD + CHF, n = 33). The relationship among NP concentrations, LA size, and E/E(a) was examined. The ability of NP to distinguish control from study cats, and HD - CHF from HD + CHF cats, was explored using receiver operator curve analysis. RESULTS: NP concentrations were significantly lower in control than in study cats (P= .0001). The NT-proBNP concentrations were positively correlated with LA/Ao ratio (rho= 0.34; P= .02) and with E/E(a) ratio (rho= 0.68; P < .05). An NT-proBNP concentration of 49 fmol/mL gave a sensitivity and specificity of 100 and 89.3%, respectively, for correctly distinguishing 96.2% of control from study cats. Pairwise comparisons of the areas under the curve identified a statistically significant difference (P= .011) between NT-proANP and NT-proBNP to distinguish control from study cats. NT-proANP and NT-proBNP concentrations were significantly higher in HD + CHF cats than in HD - CHF cats (P= .0023 and .0001, respectively). CONCLUSIONS: Serum concentrations of NT-proANP and particularly NT-proBNP were different in healthy control cats, asymptomatic cats with HD, and cats with CHF, suggesting that measurement of NP concentrations may prove clinically useful as an initial screening test for cats with suspected cardiac disease.

Double chambered right ventricle in 9 cats.

BACKGROUND: Double-chambered right ventricle (DCRV) is a frequently recognized cardiac congenital abnormality in humans. It has been described in dogs and in 1 cat. However systemic description of clinical and echocardiographic features of the disease in cats is currently lacking from the veterinary literature. ANIMALS: Nine cats with DCRV are described. RESULTS: The cats ranged from 4 months to 10 years of age. Eight cats at presentation were asymptomatic and 1 cat had chylothorax. In all cases echocardiography revealed abnormal fibromuscular bundles obstructing the mid-right ventricle, dividing the chamber into 2 compartments. The proximal right ventricular compartment was markedly hypertrophied, and right atrial dilation was usually present. The mean pressure gradient measured across the stenotic area was 130 +/- 50 mm Hg. Concurrent abnormalities included a ventricular septal defect (n = 2); aortic malalignment, aortic insufficiency (n = 1); and congenital peritoneal-pericardial diaphragmatic hernia (n = 1). Two cats had systolic anterior motion of the mitral valve, one of which had concurrent left ventricular hypertrophy. Five cats have remained asymptomatic for a median period of 3.6 years (range, 3.3-5 years) and 3 cats have developed clinical signs associated with congestive heart failure (at 2, 3.3, and 9 years). One cat showed progressive lethargy and exercise intolerance and underwent partial ventriculectomy at the age of 2 years. This cat died during the operation with electromechanical dissociation. CONCLUSIONS: DCRV is a congenital cardiac abnormality that may be more common than previously recognized.