Right atrioventricular valve malformation in dogs and cats: an electrocardiographic survey with emphasis on splintered QRS complexes

Aorto-left atrial fistula secondary to aortic infective endocarditis in a dog with a bicuspid aortic valve

An 11-year-old male neutered American bulldog was presented for evaluation of thrombocytopenia, acute onset of ataxia, and vomiting. A new murmur was auscultated on physical examination. Transthoracic echocardiographic examination revealed a bicuspid aortic valve, vegetative lesions on the aortic valve, and continuous shunting from the aortic root to the left atrium through an aorta to left atrial fistula. The dog was euthanized due to its guarded prognosis and critical condition. Pathological examination confirmed presence of a bicuspid aortic valve, aorto-left atrial fistula, and aortic infective endocarditis. Antemortem blood culture revealed two unusual organisms: Achromobacter xylosoxidans and Fusobacterium mortiferum.

Molecular Pathways and Animal Models of Ebstein's Anomaly

Ebstein's anomaly is a congenital malformation of the tricuspid valve characterized by abnormal attachment of the valve leaflets, resulting in varying degrees of valve dysfunction. The anatomic hallmarks of this entity are the downward displacement of the attachment of the septal and posterior leaflets of the tricuspid valve. Additional intracardiac malformations are common. From an embryological point of view, the cavity of the future right atrium does not have a direct orifice connected to the developing right ventricle. This chapter provides an overview of current insight into how this connection is formed and how malformations of the tricuspid valve arise from dysregulation of molecular and morphological events involved in this process. Furthermore, mouse models that show features of Ebstein's anomaly and the naturally occurring model of canine tricuspid valve malformation are described and compared to the human model. Although Ebstein's anomaly remains one of the least understood cardiac malformations to date, the studies summarized here provide, in aggregate, evidence for monogenic and oligogenic factors driving pathogenesis.

Cardiac Disease and Screening in Breeding Dogs

Acquired and congenital heart diseases are relatively common in dogs, particularly in certain breeds. Modes of inheritance and genetic causes have been established for several cardiac diseases within various breeds. Breed screening is used to try and reduce the prevalence of certain canine cardiac diseases. Although breed screening seems to help reduce the prevalence of canine heart disease, the outcomes of specific breeding programs are variable and depend on multiple factors.

A multicenter, retrospective study of cardiac disease in Borzoi dogs

Borzoi are large, relatively uncommon sighthounds anecdotally reported to suffer from sudden death. This multicenter retrospective cohort study aimed to describe the sample of Borzoi presenting to veterinary cardiologists for evaluation, with records searched from 14 centers across a study period of up to 20 years. The study sample was comprised of 152 client-owned Borzoi, with dogs most commonly presenting for pre-breed screening in 87/152 (52%), followed by evaluation of an arrhythmia in 28/152 (18%). Of the 131/152 (86%) dogs that had an echocardiogram performed, 85/131 (65%) were structurally normal, with 40/85 (47%) structurally normal dogs having trace or mild atrioventricular valve regurgitation. Tricuspid valve dysplasia was the most commonly diagnosed congenital cardiac disease (n = 6). Myxomatous mitral valve disease (n = 12) and dilated cardiomyopathy (n = 13) were diagnosed at similar frequencies, though 92% of valve disease cases were mild. Only 48/152 (32%) Borzoi had a diagnostic electrocardiogram (ECG) and/or a Holter monitor for arrhythmia screening. Despite this, ventricular arrhythmias were identified during the entirety of the available cardiac evaluation including diagnostic ECG, contemporaneous ECG monitoring during the echocardiogram, and/or Holter monitor in 25/131 (19%) dogs in which an echocardiographic diagnosis was available. Of these 25 Borzoi, 76% had minimal or no structural cardiac disease identified, and five had a family history of sudden death. A sudden death outcome was reported in 3/55 (5%) Borzoi with long-term outcome data available. In conclusion, Borzoi commonly have trace or mild atrioventricular valve insufficiencies, and may develop ventricular arrhythmias and dilated cardiomyopathy.

Percutaneous Balloon Dilation in Two Dogs with Cor Triatriatum Dexter

Percutaneous balloon dilation was performed in a Rhodesian Ridgeback and in an American Staffordshire Terrier affected by cor triatriatum dexter (CTD). Both cases had ascites without jugular venous distension or pleural effusion. In both dogs the CTD presented a perforated membrane but with different morphology: in one case the coronary sinus entered the caudal chamber of the CTD together with the caudal vena cava. In the other case, the coronary sinus communicated with the cranial chamber of the CTD together with the cranial vena cava. Percutaneous balloon dilation of the CTD was successfully performed, and both dogs had uneventful surgery recoveries. At two years of follow-up, the dogs were free from clinical signs and cardiac medication.

Retrospective evaluation of notched and fragmented QRS complex in dogs with naturally occurring myxomatous mitral valve disease

Myxomatous mitral valve disease (MMVD) is the most common cardiac disease in dogs. The association of QRS notching (nQRS) or fragmentation (fQRS) with disease severity is currently unknown. The study objective was to assess the prevalence of nQRS and fQRS in dogs with MMVD and its severity according to ACVIM classification and to compare the results with a group of healthy dogs. This retrospective cross-sectional study included 34 healthy control dogs and 155 dogs with spontaneous MMVD (42% of dogs in class B1, 23% in class B2 and 35% in class C). fQRS was defined as nQRS complexes in two contiguous leads in the frontal plane (leads I and aVL) and (II, III or aVF). A one-way ANOVA with Bonferroni post-hoc test was used to assess the differences in continuous data between control and MMVD groups. Of the MMVD group, 58% showed nQRS in at least one lead and 27% presented fQRS. There was no difference between the number of leads with a nQRS and disease severity (p = 0.75) nor did the number of leads with a nQRS correlate with left atrial size (r = 0.48; p = 0.5). The number of dogs with fQRS did not differ among classes of MMVD (p = 0.21). nQRS and fQRS were more prevalent in dogs with MMVD compared to control dogs (p < 0.01). This study did not identify any relationship between the number of leads with a nQRS and disease severity. However, dogs with MMVD had a higher prevalence of nQRS and fQRS compared to control group.

The effects of breed, age, sex, and body weight on electrocardiographic parameters in military working dogs

Aim:

This study aimed to investigate the effects of breed, sex, age, and body weight on different electrocardiographic parameters in military working dogs (Labrador Retriever and German Shepherd).

Materials and Methods:

Electrocardiographic recordings (paper speed = 25 mm/s and calibration = 10 mm/mV) were performed to obtain all the standard bipolar limb leads (leads I, II, and III) and unipolar augmented limb leads (leads aVR, aVL, and aVF). A total of 16 Labrador Retrievers and 14 German Shepherds were restrained manually in the right lateral recumbency without any tranquilizer or anesthetic drug. Amplitude and duration of P, QRS, and T wave, PR and QT interval, mean electrical axis, and heart rate were measured in each recording.

Results:

There was no significant difference in electrocardiographic parameters across breed and sex. However, QRS duration tended to alter by breed (p<0.1) in Labrador Retrievers (0.04±0.005 s), which is lower than German Shepherds (0.05±0.005 s). PR interval was influenced by sex (p<0.1). PR interval was higher in females (0.13±0.005 s) than males (0.11±0.008 s). In addition, electrocardiographic values were not significantly affected by age and body weight, except that the amplitude of R wave was statistically affected by age (p<0.05). A correlation was found between the decrease in R wave amplitude and increase in age of dogs.

Conclusion:

Different electrocardiographic parameters were within the normal range. A significant effect of age was seen on amplitude of R wave. However, the effect of breed, sex, and body weight was not significant on different electrocardiographic parameters in Labrador Retriever and German Shepherd dogs.

Epidemiological, clinical, and echocardiographic features, and outcome of dogs with Ebstein's anomaly: 32 cases (2002-2016)

INTRODUCTION/OBJECTIVES

Ebstein's anomaly (EA) is a congenital heart disease characterized by apical displacement of the tricuspid valve leaflets in the right ventricle. The objective of this retrospective study was to investigate the signalment, clinical features, echocardiographic findings, and outcome of dogs with EA.

ANIMALS, MATERIALS AND METHODS

Medical records of 40 dogs with EA were reviewed. Echocardiographic variables used to assess EA severity in human pediatrics were also evaluated (e.g. displacement index, Celermajer index, Carpentier class, and apex-mitral annulus:apex-tricuspid annulus distance ratio).

RESULTS

Labrador retriever was the most commonly recruited breed (24 of the 40 dogs, 60%). Eight of the 40 dogs with EA had hemodynamically compromising concurrent heart (n = 7) or respiratory diseases (n = 1). A right apical systolic heart murmur (median grade = 5/6) was detected in the remaining 32 dogs, without any other clinical sign related to EA in 19 of the 32 dogs (59%). Median (interquartile range) values of the displacement index and Celermajer index were 17.4 mm/m² (12.0-21.9) and 100% (50-130), respectively. Median time to all-cause death was 74 months, and 72% dogs (95% confidence interval, 50-86%) had not succumbed to cardiac death (CD) 160 months after diagnosis. Univariate analyses showed that the time from diagnosis to CD was associated with the presence of clinical signs, ascites, severe right atrial dilation, palpable thrill, and a Celermajer index ≥100%.

DISCUSSION

Right atrial enlargement is significantly associated with decreased survival time of dogs with EA although most may live for years and may not die from CD.

CONCLUSIONS

These results support medium to long-term survival for most dogs with EA.

Cor triatriatum dexter in 17 dogs

OBJECTIVES

The objective of this study was to report the signalment, presentation, clinical and imaging findings, interventions, and outcomes in a group of dogs with cor triatriatum dexter (CTD).

ANIMALS

Seventeen client-owned dogs.

METHODS

Medical records were reviewed retrospectively for signalment, history, physical examination findings, imaging and diagnostic findings, presence of concurrent congenital cardiac defects, description of interventional procedures, therapy information, and outcomes.

RESULTS

Age at presentation ranged from two to 110 months, with 10 of 17 dogs (59%) aged <12 months. There was an equal distribution between the sexes. Peritoneal effusion was the most common presenting complaint, in 10 of 17 dogs (59%). The CTD was an isolated finding in 3 of 17 dogs (18%); the remaining 14 of 17 (82%) dogs had concurrent cardiac disease, with congenital anomalies present in 12 of 17 (70%). All except one of these 12 dogs had at least one additional condition affecting the right heart. Tricuspid valve dysplasia was the most common congenital comorbidity, present in 9 of 17 dogs (53%). Seven dogs (41%) underwent interventional treatment of their CTD. In 7 of 17 (41%) cases, the CTD was considered to be incidental and the dogs were asymptomatic; therefore, no interventions were performed. The remaining three cases were euthanized or lost to follow-up.

CONCLUSIONS

Cor triatriatum dexter in dogs is commonly seen in association with other right-sided congenital cardiac anomalies and may be an incidental finding. Dogs with CTD obstructing right atrial inflow can have a good outcome after intervention. Dogs with no clinical signs associated with the CTD may remain asymptomatic into adulthood.

Retrospective evaluation of notched QRS complexes in dogs: 85 cases

INTRODUCTION

Notched QRS complexes on electrocardiography (ECG) have been described in veterinary and human reports, but little is known about this finding in veterinary patients. Therefore, the objectives of this study were to describe the signalment and cardiac disease diagnosis in dogs with notched QRS complexes, as well as to describe the specific leads and number of leads with notched QRS complexes on ECG.

ANIMALS

Eighty-five dogs with notched QRS complexes of normal duration in at least one ECG lead.

METHODS

Retrospective review of digitally stored ECGs and associated medical records of dogs with a recorded ECG as part of routine clinical evaluation.

RESULTS

Age at time of ECG recording was 9.15 ± 3.38 years for the 85 dogs with notched QRS complexes in at least one ECG lead. The number of ECG leads with notched QRS complexes did not increase with age. Most dogs (69.4%) with notched QRS complexes had cardiac disease. The odds ratio of a dog having cardiac disease if more than one lead was identified with notched QRS complexes was 3.97. The most common cardiac disease identified was chronic atrioventricular valvular degeneration, and the majority of these dogs (80%) had two or less leads with notched QRS complexes.

CONCLUSIONS

Dogs with and without cardiac disease can have notched QRS complexes. The likelihood of a dog having cardiac disease that has more than one ECG lead with notched QRS complexes is significant, and this should warrant diagnostic evaluation.

Tricuspid valve dysplasia: A retrospective study of clinical features and outcome in dogs in the UK

The objective of this study was to determine the demographic, clinical and survival characteristics and to identify risk factors for mortality due to tricuspid valve dysplasia in UK dogs. Records of client-owned dogs diagnosed with tricuspid valve dysplasia at a referral centre were retrospectively reviewed. Only dogs diagnosed with tricuspid valve dysplasia based on the presence of a right-sided heart murmur identified prior to one year of age, and confirmed with Doppler echocardiography, were included. Dogs with concomitant cardiac diseases, pulmonary hypertension and/or trivial tricuspid regurgitation were excluded. Analysed data included signalment, reason for presentation, clinical signs, electrocardiographic and echocardiographic features, survival status and cause of death. Survival times and risk factors for mortality were evaluated using Kaplan-Meier curves and Cox regression. Eighteen dogs met inclusion criteria. Border collies were over-represented (p= 0.014). Dogs were most frequently referred for investigation of heart murmur. The most common arrhythmia was atrial fibrillation (n=3). Median survival time from diagnosis of tricuspid valve dysplasia was 2775 days (range 1-3696 days; 95% CI 1542.41-4007.59) and from onset of right-sided congestive heart failure was 181 days (range 1-2130 days; 95% CI 0-455.59). Syncope was the sole risk factor for cardiac death. In this population of UK dogs, tricuspid valve dysplasia was uncommon but, when severe, frequently led to right-sided congestive heart failure. Prognosis was favourable for mild and moderate tricuspid dysplasia. Survival time was reduced with right-sided congestive heart failure but varied widely. Risk of cardiac death was significantly increased if syncope had occurred.

Sequential segmental classification of feline congenital heart disease

Feline congenital heart disease is less commonly encountered in veterinary medicine than acquired feline heart diseases such as cardiomyopathy. Understanding the wide spectrum of congenital cardiovascular disease demands a familiarity with a variety of lesions, occurring both in isolation and in combination, along with an appreciation of complex nomenclature and variable classification schemes. This review begins with an overview of congenital heart disease in the cat, including proposed etiologies and prevalence, examination approaches, and principles of therapy. Specific congenital defects are presented and organized by a sequential segmental classification with respect to their morphologic lesions. Highlights of diagnosis, treatment options, and prognosis are offered. It is hoped that this review will provide a framework for approaching congenital heart disease in the cat, and more broadly in other animal species based on the sequential segmental approach, which represents an adaptation of the common methodology used in children and adults with congenital heart disease.

The occurrence and suspected mode of inheritance of congenital subaortic stenosis and tricuspid valve dysplasia in Dogue de Bordeaux dogs

The Dogue de Bordeaux (DdB) breed has gone through several genetic 'bottle necks' and has a relatively small effective population size. Importing new stock into Israel has been limited, further narrowing the already restricted local gene-pool and increasing the chances of inherited defects. In 56 DdB dogs examined between 2003 and 2010, the authors sought to study the proportion congenital subaortic stenosis (SAS) and tricuspid valve dysplasia (TVD). The aim was also to identify a probable mode of inheritance (MOI) using segregation and pedigree analyses of genealogical data available from 13/21 DdB dogs diagnosed with these conditions between 2004 and 2007. Among all breeds in the country, TVD was highest in the DdB breed, which also displayed the second highest proportion of SAS. Echocardiographic measurements and selected physical examination findings from 26 normal DdB dogs, 18 DdB dogs with SAS, and 12 DdB dogs with TVD are reported. Based on pedigree and segregation analyses, the most probable MOI appeared to be autosomal recessive. Pedigree analyses helped to identify three ancestors that might have introduced these two congenital heart defects into the local DdB population. Excluding those three dogs and their progeny from future mating could therefore reduce the prevalence of these diseases in the DdB population in Israel. The unusual local breeding circumstances may offer a unique opportunity to identify associated SAS and TVD genes in the DdB, as well as in other dog breeds.

Atrioventricular Canal Defect (incomplete form of endocardial cushion defect) and Ostium Secundum Type Interatrial Septal defect in a dog

A four-year-old German shepherd mixed-breed dog was presented with an asymptomatic heart murmur. An atrial septal defect associated with tricuspid and mitral dysplasia (atrioventricular canal defect) was diagnosed. The pulmonary to systemic blood flow ratio was in the range of 2.5:1 (Qp:Qs ratio). Echocardiography and flow pattern across the valves as well as the direction of the shunt allows a better description of the physiopathological consequences of this rare congenital heart disease. Additionally, an Ostium Secundum Type interatrial septum defect was found at necropsy.

Tricuspid valve dysplasia and Ebstein's anomaly in dogs: case report

Two cases of tricuspid valve dysplasia are reported. Dogs were presented for evaluation of weakness and ascites. In both cases, echocardiography disclosed tricuspid insufficiency and, in one of them, tricuspid leaflets also were displaced down into the right ventricle, substantiating Ebstein's anomaly. Medical therapy for congestive heart failure was initiated. One of the dogs suddenly died shortly after diagnosis was established. Although the other dog recovered much better initially, sudden death also occurred. Post-mortem examinations showed right atrioventricular enlargement, and thickened tricuspid leaflets. Clinical features, diagnostic methods and medical therapy are discussed in this paper.

Congenital Heart Diseases of Puppies and Kittens

Congenital heart disease (CHD) is defined as a morphologic defect of the heart or associated great vessels present at birth. Abnormalities are caused by alterations or arrests in particular phases of embryonic development of the fetal heart. The term congenital does not imply that the defect was inherited, and the defect may have occurred spontaneously or secondary to a drug or toxin. By studying families of animals with specific CHDs, many defects have also been shown to be heritable.Additionally, if the defect was caused by a spontaneous de novo mutation,that individual has the potential to transmit the mutation to offspring. The diagnosis of CHD is important not only to the health of the patient but to eliminate affected individuals from the breeding pool.

Atrial septal defect in five dogs

The clinical, electrocardiographic, radiographic, and two-dimensional, M-mode and Doppler echocardiographic findings of five cases of canine ostium secundum type atrial septal defect (ASD) are described. The atrial septal anomaly was associated with other congenital cardiac abnormalities in two dogs: ventricular septal defect in one case and tricuspid dysplasia in the other. ASD was found in addition to dilated cardiomyopathy and suspected atrial thrombosis in one geriatric dog, but was the only cardiac abnormality detected in the remaining two dogs. Colour Doppler imaging facilitated the diagnosis of ASD in all subjects. The long-term prognosis for dogs with isolated and small-sized ASD is usually good, but can be compromised by the presence of concurrent congenital or acquired cardiac diseases.