Long-term Intrinsic Rhythm Evaluation in Dogs with Atrioventricular Block

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: 7 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 (4/24). 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 7, 4, 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

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.

Left Atrial Tachycardia and Third-Degree Atrioventricular Block in a Dog

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SVT may affect only the LA in the dog.

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Spectral and 2D Doppler echocardiography help confirm that an SVT is confined to the LA.

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Left atrial SVT was identified by comparing MV and TV inflows via spectral Doppler.

Unusual Presentation of Aortic Valve Infective Endocarditis in a Dog: Aorto-Cavitary Fistula, Tricuspid Valve Endocarditis, and Third-Degree Atrioventricular Block

Simple Summary

In dogs, infective endocarditis represents a rare but clinically relevant disease that typically involves the aortic and/or mitral valve. Transthoracic echocardiography plays an essential role in the diagnosis, prognosis, and monitoring of such a condition. Typical echocardiographic signs of disease progression include left-sided cardiac dilatation and extension of aortic and/or mitral vegetative lesions. Nevertheless, unexpected complications can sometimes develop, especially in the case of the erosion of the periannular tissue caused by lytic enzymes produced by bacteria. This case report describes the coexistence of multiple, uncommon complications of aortic valve infective endocarditis in a dog, namely, aorto-cavitary fistula, tricuspid valve endocarditis and third-degree atrioventricular block. In this study, the combination of the ante mortem (clinical and echocardiographic) and post mortem (gross pathology and histopathology) findings allowed us to gain detailed information on the disease process, its atypical complications, and the associated emodynamic consequences.

Abstract

A 2-year-old Boxer with a history of subaortic stenosis and immunosuppressant therapy developed aortic valve infective endocarditis. On echocardiographic examination with simultaneous electrocardiographic tracing, multiple uncommon periannular complications of the aortic valve endocarditis were found, including aorto-cavitary fistula with diastolic left-to-right shunt, tricuspid valve endocarditis, and third-degree atrioventricular block. Necropsy confirmed the above echocardiographic findings. Although aortic valve endocarditis represents a well-known disease entity in dogs, the dynamic nature of this condition may allow development of complex and uncommon echocardiographic features.

Prevalence of selected cardiotropic pathogens in the myocardium of adult dogs with unexplained myocardial and rhythm disorders or with congenital heart disease

OBJECTIVE

To determine the prevalence of nucleic acid from selected cardiotropic pathogens in endomyocardial biopsy samples from dogs with unexplained myocardial and rhythm disorders (UMRD) and compare prevalence with that for a group of control dogs with congenital heart disease (CHD).

ANIMALS

47 client-owned dogs.

PROCEDURES

Right ventricular endomyocardial biopsy was performed in dogs with UMRD (dilated cardiomyopathy [n = 25], atrioventricular block [6], and nonfamilial ventricular [4] and supraventricular arrhythmias [2]) or CHD (10) that required right ventricular catheterization. Biopsy samples were evaluated histologically, and PCR assays were used for detection of nucleic acid from 12 pathogens.

RESULTS

197 biopsy samples were collected from dogs with UMRD (n = 172) or CHD (25). At least 1 pathogen was detected in 21 of 37 (57%; 95% confidence interval [CI], 41% to 71%) dogs with UMRD, and canine coronavirus was detected in 1 of 10 (10%; 95% CI, 2% to 40%) dogs with CHD. Dogs with UMRD were significantly more likely than dogs with CHD to have pathogens detected in biopsy samples (OR, 11.8; 95% CI, 1.3 to 103.0). The most common pathogens in dogs with UMRD were canine distemper virus, canine coronavirus, canine parvovirus 2, and Bartonella spp. No pathogens were detected in available blood samples from dogs with pathogens detected in biopsy samples.

CONCLUSIONS AND CLINICAL RELEVANCE

Detection of nucleic acids from selected cardiotropic pathogens in myocardial tissue from dogs with UMRD suggested a possible association between the 2. Further studies are needed to explore whether this association is causative or clinically important. (J Am Vet Med Assoc 2019;255:1150-1160).

Retrospective Analysis of Indications and Complications Related to Implantation of Permanent Pacemaker: 25 Years of Experience in 31 Dogs

Introduction

Pacemaker implantation is the only effective symptomatic treatment for life-threatening bradyarrhythmias. Major complications observed after implantation of cardiac pacemakers include lead dislocation, loss of pulse generator function, and inadequate stimulation. The aim of this retrospective single-centre study was to analyse the indications for pacemaker implantation and the incidence and types of complications associated with this procedure in dogs treated for symptomatic bradyarrhythmia.

Material and Methods

The retrospective analysis included 31 dogs with symptomatic bradyarrhythmia, implanted with permanent cardiac pacemakers in 1992-2017. The list of analysed variables included patient age, breed, sex, indication for pacemaker implantation, comorbidities, and the incidence of procedure-related complications along with the type thereof.

Results

The most common indication for pacemaker implantation was 3^rd degree AVB, followed by SSS, advanced 2^nd degree AVB, and PAS. Pacemaker implantation was associated with a 35% overall complication rate and 6.45% periprocedural mortality. There were no significant differences in terms of procedure-related complications with regard to age, sex, breed, indications for pacemaker implantation, or comorbidities.

Conclusions

Cardiac pacing is the only effective treatment of symptomatic bradycardia, but as an invasive procedure, may pose a risk of various complications, including death.

Indications for permanent pacing in dogs and cats

Pacemaker implantation is considered as a standard procedure for treatment of symptomatic bradycardia in both dogs and cats. Advanced second-degree and third-degree atrioventricular blocks, sick sinus syndrome, persistent atrial standstill, and vasovagal syncope are the most common rhythm disturbances that require pacing to either alleviate clinical signs or prolong survival. Most pacemakers are implanted transvenously, using endocardial leads, but rarely epicardial leads may be necessary. To decide whether a patient is a candidate for pacing, as well as which pacing modality should be used, the clinician must have a clear understanding of the etiology, the pathophysiology, and the natural history of the most common bradyarrhythmias, as well as what result can be achieved by pacing patients with different rhythm disturbances. The goal of this review was, therefore, to describe the indications for pacing by evaluating the available evidence in both human and veterinary medicine. We described the etiology of bradyarrhythmias, clinical signs and electrocardiographic abnormalities, and the choice of pacing modality, taking into account how different choices may have different physiological consequences to selected patients. It is expected that this review will assist veterinarians in recognizing arrhythmias that may require permanent pacing and the risk-benefit of each pacing modality and its impact on outcome.