Detection of the origin of atrial tachycardia by 3D electro‐anatomical mapping and treatment by radiofrequency catheter ablation in horses

BackgroundAtrial tachycardia (AT) can be treated by medical or electrical cardioversion but the recurrence rate is high. Three‐dimensional electro‐anatomical mapping, recently described in horses, might be used to map AT to identify a focal source or reentry mechanism and to guide treatment by radiofrequency ablation.ObjectivesTo describe the feasibility of 3D electro‐anatomical mapping and radiofrequency catheter ablation to characterize and treat sustained AT in horses.AnimalsNine horses with sustained AT.MethodsRecords from horses with sustained AT referred for radiofrequency ablation at Ghent University were reviewed.ResultsThe AT was drug resistant in 4 out of 9 horses. In 8 out of 9 horses, AT originated from a localized macro‐reentrant circuit (n = 5) or a focal source (n = 3) located at the transition between the right atrium and the caudal vena cava. In these 8 horses, local radiofrequency catheter ablation resulted in the termination of AT. At follow‐up, 6 out of 8 horses remained free of recurrence.Conclusions and Clinical ImportanceDifferentiation between focal and macro‐reentrant AT in horses is possible using 3D electro‐anatomical mapping. In this study, the source of right atrial AT in horses was safely treated by radiofrequency catheter ablation.     

Over-expressed calreticulin interacts with integrin-α5 and calcineurin system to induce atrial remodeling in patients with atrial fibrillation and valvular disease

AIM: To determine whether calreticulin over-expression contributes to atrial fibrosis in the patients with atrial fibrillation (AF) and valvular heart disease (VHD).METHODS: Right and left atrial specimens were obtained from 78 patients undergoing valve replacement surgery. The patients were divided into sinus rhythm (SR) group, paroxysmal AF (PaAF) group and persistent AF (PeAF, AF lasting >6 months) group. The protein expression of calreticulin, integrin-α5, and transforming growth factor-β1 (TGF-β1) was measured. Immunoprecipitation was also performed to determine whether calreticulin interacted with either calcineurin B or integrin-α5. RESULTS: The protein expression of calreticulin, integrin-α5 and TGF-β1 was increased in AF groups, especially in the left atrium of the patients with mitral valve disease as compared with SR group. Calreticulin interacted with both calcineurin B and integrin-α5. The expression level of integrin-α5 was significantly correlated with the expression level of TGF-β1, while the expression level of calreticulin was correlated with that of integrin-α5 and TGF-β1. Under similar classification of the cardiac function, the expression level of calreticulin in PeAF group was higher than that in SR group. CONCLUSION: The expression of calreticulin, integrin-α5, and TGF-β1 is increased in the atrial tissues of the AF patients and is related to the AF type, suggesting that calreticulin is involved in atrial remodeling in AF and VHD patients.     

Comparison of different radiographic scores with associated echocardiographic measurements and prediction of heart enlargement in dogs with and without myxomatous mitral valve disease

IntroductionStaging of myxomatous mitral valve disease (MMVD) requires an echocardiographic examination along with thoracic radiographs. The aims of this study were to calculate mean values for radiographic scores vertebral heart size (VHS), left atrial width (LA_Width), radiographic left atrial dimension (RLAD), and vertebral left atrial size (VLAS) in conventional and grayscale inverted images in healthy dogs and dogs with different stages of MMVD, and to find cutoff values for a stage assignment.AnimalsOne hundred fifty dogs in different stages of MMVD and 50 unaffected dogs were evaluated.MethodsRadiographic scores, echocardiographic left atrium-to-aorta ratio and normalized left ventricular internal dimension at end-diastole, and results of a clinical examination were obtained. Analyses were performed to evaluate the correlation between radiographic scores and echocardiographic values, to determine cutoff values for a radiographic stage assignment, and to compare measurements in conventional and inverted radiographs.ResultsAfter excluding breed-specific higher VHS, the means of VHS, LA_Width, RLAD, and VLAS were similar in the control group and stage B1. All radiographic scores increased in stages B2 and C. The cutoff values identifying heart enlargement, and therefore differentiating stages B1 and B2, were 11.0 for VHS, 1.8 for LA_Width, 2.0 for RLAD, and 2.3 for VLAS. Besides RLAD, scores were similar in conventional and inverted radiographs.ConclusionCutoff values for the different radiographic scores for stage assignment were calculated. Radiographic cardiac scores using either conventional or inverted grayscale could be a tool to differentiate between different stages of MMVD when echocardiography is unavailable.