Long-term management of atrial myopathy in two dogs with single chamber permanent transvenous pacemakers

Single center retrospective clinical audit and comparison of outcome between epicardial and transvenous endocardial permanent pacemaker implantations in dogs

The aim of this retrospective cohort study was to provide a single-center clinical audit of complications for single chamber permanent pacemaker implantation (PPI) techniques and determine if the clinical parameters, PPI technique or complications were associated with outcome. The electronic medical records were searched for dogs treated for bradyarrhythmia with PPI. Data related to presenting complaint, signalment of the dog, ECG diagnosis, echocardiographic findings, PPI technique, and programing of the pacemaker were recorded. Survival length (days) was recorded as the last veterinary visit; if the dog was dead the reason was documented. Cumulative survival of each pacemaker was examined by a Kaplan-Meier survival curve and the two techniques compared with a logrank test. Chi-square was used to determine the association between major complications and death. A total of 66 dogs with 52 transvenous and 30 epicardial PPIs were included. All epicardial pacemakers were implanted via transdiaphragmatic approach. A total of 31 life-threatening complications were reported. There were nine deaths related to major complications (13.6% of the study sample). The median follow-up period was 366 days, with a median survival of 255 days, and a significant difference in cumulative survival of each pacemaker (P = 0.01) between epicardial (93 days, range 0-1882 days) and transvenous (334 days, range 0-2745) PPIs but no significant difference in cumulative survival between the two techniques when only the first pacemaker was considered (p = 0.07). The presence of a major complications had a significant association with death due to pacemaker complications (P<0.001). The decision to perform epicardial PPI in failed transvenous PPI patients may have skewed the cumulative survival as was evident in the lack of significant difference in survival when only first PPI were examined. Major complication rates between the two techniques were similar and the authors consider both techniques equally reliable to manage symptomatic bradycardia in dogs.

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.

2022 Update of the Consensus on the Rational Use of Antithrombotics and Thrombolytics in Veterinary Critical Care (CURATIVE) Domain 1- Defining populations at risk

OBJECTIVES

To expand the number of conditions and interventions explored for their associations with thrombosis in the veterinary literature and to provide the basis for prescribing recommendations.

DESIGN

A population exposure comparison outcome format was used to represent patient, exposure, comparison, and outcome. Population Exposure Comparison Outcome questions were distributed to worksheet authors who performed comprehensive searches, summarized the evidence, and created guideline recommendations that were reviewed by domain chairs. The revised guidelines then underwent the Delphi survey process to reach consensus on the final guidelines. Diseases evaluated in this iteration included heartworm disease (dogs and cats), immune-mediated hemolytic anemia (cats), protein-losing nephropathy (cats), protein-losing enteropathy (dogs and cats), sepsis (cats), hyperadrenocorticism (cats), liver disease (dogs), congenital portosystemic shunts (dogs and cats) and the following interventions: IV catheters (dogs and cats), arterial catheters (dogs and cats), vascular access ports (dogs and cats), extracorporeal circuits (dogs and cats) and transvenous pacemakers (dogs and cats).

RESULTS

Of the diseases evaluated in this iteration, a high risk for thrombosis was defined as heartworm disease or protein-losing enteropathy. Low risk for thrombosis was defined as dogs with liver disease, cats with immune-mediated hemolytic anemia, protein-losing nephropathy, sepsis, or hyperadrenocorticism.

CONCLUSIONS

Associations with thrombosis are outlined for various conditions and interventions and provide the basis for management recommendations. Numerous knowledge gaps were identified that represent opportunities for future studies.

Pathological Features of Persistent Atrial Standstill Syndrome in Three Dogs

The hearts of three dogs, clinically diagnosed as having persistent atrial standstill syndrome (PAS), were studied post mortem. The most significant gross findings in the hearts of all three dogs were dilatation and marked reduction in the thickness of both atrial walls. Histopathologically, all three had widespread progressive loss of the atrial myocardium with replacement by fatty or fibrofatty tissue, consistent with atrial myopathy. The lesion mainly affected the upper half of both atria and was more severe in the epimyocardium and midmyocardium than in the endomyocardium. On the basis of these observations, it is proposed that the atrial myopathy commences in the upper regions of both atria and progresses downwards, as has been demonstrated electrophysiologically in PAS in humans, and extends from the epicardium towards the endocardium.

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.