Clinical presentation, management, and survival in dogs with persistent atrial standstill in the United Kingdom.

OBJECTIVES: To investigate the clinical and echocardiographic presentation of dogs with persistent atrial standstill (PAS), identify variables measured at first presentation that could predict their survival, and document the progression of the disease after pacing. MATERIALS AND METHODS: Retrospective study of medical records of dogs diagnosed with PAS at three referral hospitals of the United Kingdom over seven years. RESULTS: Twenty-six dogs were diagnosed with PAS during the study period. Median age of the population was three years (range: seven months-12.5 years). The most common clinical sign was syncope (14/26). Twenty-four dogs received artificial pacemakers (PM). Major complications after PM implantation were observed in four dogs (four/24). Serial echocardiographic examinations showed that cardiac dimensions of PAS dogs with left atrial or left ventricular dilation at first presentation did not return to reference range after pacing. Further dilation of the cardiac chambers, recurrence of congestive heart failure (CHF), or development of new episodes of CHF were documented in seven, four, and 10 PAS dogs, respectively, despite pacing. Median survival time for cardiac-related deaths after PM implantation was 1512 days (18-3207). Neither CHF nor echocardiographic variables at presentation predicted survival after PM implantation in PAS dogs. CONCLUSIONS: Persistent atrial standstill (PAS) is an uncommon bradyarrhythmia, occurring in young adult dogs. Affected dogs were often presented with syncope. Whilst syncope resolved, cardiac remodeling persisted after PM implantation. Long-term survival was favorable after PM implantation and was not predicted by congestive status or cardiac chamber size at first presentation.

Pacemaker-lead-associated thrombosis in dogs: a multicenter retrospective study.

INTRODUCTION: Pacemaker implantation is the treatment of choice for clinically relevant bradyarrhythmias. Pacemaker-lead-associated thrombosis (PLAT) occurs in 23.0-45.0% of people with permanent transvenous pacemakers. Serious thromboembolic complications are reported in 0.6-3.5%. The incidence of PLAT in dogs is unknown. ANIMALS, MATERIALS AND METHODS: multicenter retrospective study of seven centers with 606 client-owned dogs undergoing permanent pacemaker implantation between 2012 and 2019. 260 dogs with a transvenous pacemaker with echocardiographic follow-up, 268 dogs with a transvenous pacemaker without echocardiographic follow-up and 78 dogs with an epicardial pacemaker. RESULTS: 10.4% (27/260) of dogs with transvenous pacemakers and echocardiographic follow-up had PLAT identified. The median time to diagnosis was 175 days (6-1853 days). Pacemaker-lead-associated thrombosis was an incidental finding in 15/27 (55.6%) dogs. Of dogs with a urine protein:creatinine ratio measured at pacemaker implantation, dogs with PLAT were more likely to have proteinuria at pacemaker implantation vs. dogs without PLAT (6/6 (100.0%) vs. 21/52 (40.4%), P=0.007). Urine protein:creatinine ratio was measured in 12/27 (44.4%) dogs at PLAT diagnosis, with proteinuria identified in 10/12 (83.3%) dogs. Anti-thrombotic drugs were used following the identification of PLAT in 22/27 (81.5%) dogs. The thrombus resolved in 9/15 (60.0%) dogs in which follow-up echocardiography was performed. Dogs with PLAT had shorter survival times from implantation compared to those without PLAT (677 days [9-1988 days] vs. 1105 days [1-2661 days], P=0.003). CONCLUSIONS: Pacemaker-lead-associated thrombosis is identified in 10.4% (27/260) of dogs following transvenous pacing, is associated with proteinuria, can cause significant morbidity, and is associated with reduced survival times.

Validation of heart rate spot-check protocol to measure circadian variation and heart rate in healthy dogs and dogs with atrial fibrillation.

INTRODUCTION: Alternatives for out-of-clinic heart rate (HR) measurement are required to optimise the management of atrial fibrillation (AF) in dogs. Additionally, the presence of circadian variation (CV) in HR in pet dogs remains unknown. We aimed to identify the number and duration of spot-checks required for an accurate estimation of 24-hour HR in canine AF. Circadian variation in HR was examined in healthy dogs and dogs with AF, and spot-check-derived HR was compared with a CV-derived gold standard. MATERIALS AND METHODS: Ambulatory electrocardiogram data from healthy dogs and dogs with AF were retrospectively analysed. Heart rate was calculated from the entire recording and pre-defined periods (spot-checks) of one hour to 30 and 60 s in duration. Circadian variation in HR was determined by cosinor analysis. Bias and limits of agreement of means and median HR with mesor HR were determined by correlation and Bland-Altman analysis. RESULTS: Circadian variation in HR was identified not only in 18/22 healthy dogs and 14/21 AF dogs but only on ambulatory electrocardiogram recordings. Four-hourly spot-checks provided the most accurate estimate of mesor HR in healthy dogs (bias of the median over 30 s 7.70, limits of agreement 7.48), whereas, in dogs with AF, four, six and eight-hourly spot-checks provided reliable estimates of mesor HR (bias within -1.29 and -29.5). CONCLUSIONS: Four, six and eight-hourly HR spot-checks can estimate 24-hourly HR in dogs with AF. There was CV in HR in most healthy pet dogs and dogs with AF. Spot-check protocols cannot identify CV in HR.

Outcome clinical audit: analyses of interventional closure of patent ductus arteriosus in dogs.

OBJECTIVES: The objectives of this study were to determine whether conducting a clinical audit was achievable in a group of centres that perform interventional cardiac procedures and to report the success and complications rates in dogs diagnosed with patent ductus arteriosus. METHODS: This was a multicentre, European-wide, prospective study. Patient data were entered into a bespoke database prior to commencing interventional closure of patent ductus arteriosus in all animals undergoing this procedure during the study period. The database was designed to gather clinical audit information, after completion of the procedure, such as discharge outcome, complication rate, and medium-term outcome. RESULTS: A total of 339 cases were included from five participating centres. The process of performing clinical audit was achieved in all centres. Successful discharge outcome was 95.9% with a complication rate of 4.1%. The procedure-related mortality was 0.6%. 149 cases (43.9%) were either lost to follow-up or had not yet had a follow-up within the time period. Of the remaining 169 cases in which follow-up was available, 157 (92.9%) cases had a successful medium-term outcome CONCLUSIONS: This study demonstrates that the process of performing a clinical audit is achievable in veterinary clinical interventions across different centres. These results provide a benchmark for future comparison in our ongoing clinical audit and validate the process of clinical audit for other centres performing cardiac interventions. The use of clinical audit should be considered in other aspects of veterinary medicine.

Aortic sinus aneurysm communicating with the main pulmonary artery, and a concurrent patent ductus arteriosus, in a dog.

This is the first report of an aortic sinus aneurysm with a communication to the main pulmonary artery, resulting in left-to-right shunting, diagnosed in vivo in a dog. There was also a second left-to-right shunt through a patent ductus arteriosus. Computed tomography (CT) angiography was used to confirm both congenital anomalies and assess the relative contributions of the two left-to-right shunts to left-sided volume overload.

Eosinophilic pericardial effusion in a cat with complex systemic disease and associated peripheral eosinophilia.

An 11-year-old domestic shorthair cat was referred for investigation of dry cough of 1-week duration and cardiomegaly. Echocardiography revealed pericardial effusion, and eosinophils were identified as the predominant cell type in fluid collected by pericardiocentesis. Thoracic computed tomography imaging and bronchoscopy were supportive of mild lower airway disease, while bronchoalveolar lavage confirmed eosinophilic inflammation and concurrent Mycoplasma felis infection. A few months after the initial presentation, there was clinical deterioration, and further investigation suggested intestinal lymphoma. It was hypothesized that pericardial effusion and lower airway inflammation were an early manifestation of hypereosinophilic syndrome, possibly as a paraneoplastic consequence of lymphoma.

Balloon valvuloplasty for treatment of pulmonic stenosis in English Bulldogs with an aberrant coronary artery.

BACKGROUND: English Bulldogs (EB) with pulmonic stenosis (PS) sometimes have an aberrant coronary artery (CA) type R2A encircling the pulmonary artery (PA). Balloon valvuloplasty (BV) is treatment of choice for severe PS, but is considered to be contraindicated in dogs with aberrant CA. HYPOTHESIS: Conservative BV in EB with aberrant CA is safe and improves clinical signs and quality of life. ANIMALS: Four client-owned EB with severe PS were retrospectively reviewed/analysed. METHODS: Retrospective study: Case records, echocardiography, BV, and follow-up investigations of EB diagnosed with severe PS and treated with BV were reviewed. The ratios of PA to aortic (Ao) velocity time integral (VTI) were calculated to assess progression/improvement of PS. RESULTS: An aberrant CA was confirmed on angiography in all EB. Conservative BV was performed, using a balloon of the size of the PA annulus or smaller (0.6-1 x PA annulus size). All dogs survived the procedure, but only a mild reduction in pressure gradient was achieved. There was an improvement in PA to Ao VTI in 3 of 4 dogs (P < or = .017), which were free of evidence of congestive heart failure (CHF) 5, 10, and 15 months after BV. One dog that had right-sided CHF when BV was performed died due to progressive right-sided CHF within 3 months. CONCLUSIONS: Conservative BV in EB might be safe and might improve quality and quantity of life.

Spontaneous torsade de pointes and ventricular fibrillation in a dog during pacemaker implantation.

Torsade de pointes is an unusual complication seen in dogs during pacemaker implantation, although ventricular fibrillation has been previously reported. This case report describes torsade de pointes in a dog during pacemaker implantation that degenerated into ventricular fibrillation and discusses the possible contributory factors. It also illustrates the relevance of a pre-emptive resuscitation plan and how this might have affected the outcome in the patient.

Accessory left ventricular chamber in a cat: multimodality imaging description by cardiac magnetic resonance imaging and echocardiography.

A left ventricular accessory chamber is a complex and uncommon phenotype consisting in a subdivision of the left ventricle by a thick-walled muscle bundle or septum into two cavities. Multiple aetiologies such as congenital double-chambered left ventricle and acquired endomyocardial form of restrictive cardiomyopathy have been reported. The endomyocardial form of restrictive cardiomyopathy, owing to its structural heterogeneity, can present a similar phenotype to the congenital abnormality with intraventricular lesions bridging the ventricular septum and left ventricular free wall. Conventional echocardiography is the first-line, accepted, non-invasive imaging modality to investigate underlying cardiac disease but presents limitations for the overall assessment of myocardial tissue. This report describes the use of cardiac magnetic resonance imaging as an additional imaging modality to provide multiplanar morphological, structural, and functional information of the myocardium. In the presented images, hyperintensities on cardiac magnetic resonance imaging within the myocardium along with hyperechoic and heterogeneous myocardial tissue on echocardiography and elevated troponin I were suggestive of a presumptive acquired pathological process such as feline endomyocarditis-left ventricular endomyocardial fibrosis complex, rather than a sole congenital anomaly. Although the diagnosis was not confirmed, this case exemplifies the advantages of using complementary multimodality imaging in a cat presented with a left ventricular accessory chamber.

Glucocorticoid metabolism and the action of 11 beta-hydroxysteroid dehydrogenase 2 in canine congestive heart failure.

The enzyme 11-beta-hydroxysteroid dehydrogenase isoenzyme 2 (11BHSD2) is responsible for converting the active glucocorticoid cortisol to inactive cortisone and in the renal medulla protects the mineralocorticoid receptor (MR) from activation by cortisol. Derangements in 11BHSD2 activity can result in reduced conversion of cortisol to cortisone, activation of the MR by cortisol and, consequently, sodium and water retention. The objective of this study was to examine glucocorticoid metabolism in canine congestive heart failure (CHF), specifically to evaluate whether renal 11BHSD2 activity and expression were altered. Dogs were prospectively recruited into one of two phases; the first phase (n=56) utilized gas chromatography-tandem mass spectrometry to examine steroid hormone metabolites normalised to creatinine in home-caught urine samples. Total serum cortisol was also evaluated. The second phase consisted of dogs (n=18) euthanased for refractory CHF or for behavioural reasons. Tissue was collected from the renal medulla for examination by quantitative reverse transcription polymerase chain reaction, immunohistochemistry and protein immune-blotting. Heart failure did not change urinary cortisol:cortisone ratio (P=0.388), or modify renal expression (P=0.303), translation (P=0.427) or distribution of 11BHSD2 (P=0.325). However, CHF did increase excretion of 5α-tetrahydrocortisone (P=0.004), α-cortol (P=0.002) and α-cortolone (P=0.009). Congestive heart failure modifies glucocorticoid metabolism in dogs by increasing 5α-reductase and 20α-hydroxysteroid dehydrogenase activity. Differences between groups in age, sex and underlying disease processes may have influenced these results. However, 11BHSD2 does not appear to be a potential therapeutic target in canine CHF.

Total anomalous pulmonary venous connection in a mature dog.

A 2-year 10-month, male neutered, crossbreed dog presented for evaluation of cyanosis and exercise intolerance. Doppler echocardiography revealed severe dilation of the right atrium and right ventricle with moderate pulmonary hypertension. Right-to-left shunting across a large ostium secundum atrial septal defect was confirmed by contrast echocardiography. Thoracic radiography revealed a vascular pattern together with cardiomegaly. Computed tomography angiography identified an anomalous pulmonary venous connection in which all pulmonary veins, apart from the right middle vein, coalesced into a single, large aneurysmal vein that then drained into the right atrium via the cranial vena cava. The distal opening of the right middle pulmonary vein could not be determined. A presumptive diagnosis of partial anomalous pulmonary venous connection was made. The dog was medically managed with sildenafil (1.5 mg/kg by mouth [PO] every 8 h) and remained clinically stable for 2 months before euthanasia due to worsening exercise intolerance. On postmortem examination, all pulmonary veins, including the right middle vein, were shown to communicate with a single, large central vein. This large vein then connected with the right atrium via the cranial vena cava, consistent with a total anomalous pulmonary venous connection. This case report describes a rare congenital abnormality which has not been previously reported in a mature dog.

Poincaré plots as a measure of heart rate variability in healthy dogs.

INTRODUCTION: Poincaré plots remain largely unused for heart rate variability (HRV) analysis in dogs. The aims of this study were to describe, qualitatively and quantitatively, Poincaré plots in healthy dogs, to compare them with other methods of HRV analysis, to assess their day-to-day variability and to investigate the effect of activity on the plots. ANIMALS: Twenty-five healthy dogs. METHODS: Poincaré plots, their standard descriptors, and other measures of HRV were generated from 24-hour ambulatory electrocardiographic recordings and 6 hours of rest and activity. RESULTS: The 24-hour Poincaré plot demonstrated a 'Y' pattern. The arms of the 'Y' were derived mostly from periods of rest and activity populated the stalk. The quantitative descriptors of the plot had strong correlations in the time-domain, with weaker correlations in the frequency-domain. Individuals showed low day-to-day variability of the plot pattern and of the standard deviation of points along the major axis of the plot (SD2), which measures overall HRV. Day-to-day variability was higher for the standard deviation of points perpendicular to the major axis of the plot (SD1), which is a measure of short-term HRV, and for the SD1/SD2 ratio. CONCLUSIONS: Twenty-four-hour Poincaré plots in healthy dogs show a 'Y' pattern with subtle variations unique to the individual. The amount of activity and rest within the recording has a significant effect on the plot. Quantitative analysis of the plot can be used as a surrogate for time-domain analysis of HRV but visual analysis of the pattern provides additional information.

Immunohistochemical differentiation of reactive from malignant mesothelium as a diagnostic aid in canine pericardial disease.

OBJECTIVES: To develop a provisional immunohistochemistry panel for distinguishing reactive pericardium, atypical mesothelial proliferation and mesothelioma in dogs. MATERIALS AND METHODS: Archived pericardial biopsies were subject to haematoxylin and eosin staining, immunohistochemistry for cytokeratin, vimentin, insulin-like growth factor II mRNA-binding protein 3, glucose transporter 1 and desmin. Samples were scored for intensity and number of cells stained. RESULTS: Ten biopsies of reactive mesothelium, 17 of atypical mesothelial proliferation, 26 of mesothelioma and five of normal pericardium were identified on the basis of haematoxylin and eosin staining. Cytokeratin and vimentin were expressed in all biopsies, confirming mesothelial origin. Normal pericardial samples had the lowest scores for insulin-like growth factor II mRNA-binding protein 3, glucose transporter 1 and desmin. Mesothelioma and atypical proliferative samples were similar to each other, with higher scores for insulin-like growth factor II mRNA-binding protein 3 and glucose transporter 1 than the reactive samples. Desmin staining was variable. Insulin-like growth factor II mRNA-binding protein 3 was the best to distinguish between disease groups. CLINICAL SIGNIFICANCE: An immunohistochemistry panel of cytokeratin, vimentin, insulin-like growth factor II mRNA-binding protein 3 and glucose transporter 1 could provide superior information compared with haematoxylin and eosin staining alone in the diagnosis of cases of mesothelial proliferation in canine pericardium, but further validation is warranted.