Transfer learning in ECG classification from human to horse using a novel parallel neural network architecture

Automatic or semi-automatic analysis of the equine electrocardiogram (eECG) is currently not possible because human or small animal ECG analysis software is unreliable due to a different ECG morphology in horses resulting from a different cardiac innervation. Both filtering, beat detection to classification for eECGs are currently poorly or not described in the literature. There are also no public databases available for eECGs as is the case for human ECGs. In this paper we propose the use of wavelet transforms for both filtering and QRS detection in eECGs. In addition, we propose a novel robust deep neural network using a parallel convolutional neural network architecture for ECG beat classification. The network was trained and tested using both the MIT-BIH arrhythmia and an own made eECG dataset with 26.440 beats on 4 classes: normal, premature ventricular contraction, premature atrial contraction and noise. The network was optimized using a genetic algorithm and an accuracy of 97.7% and 92.6% was achieved for the MIT-BIH and eECG database respectively. Afterwards, transfer learning from the MIT-BIH dataset to the eECG database was applied after which the average accuracy, recall, positive predictive value and F1 score of the network increased with an accuracy of 97.1%

Differences in ultrasound-derived arterial wall stiffness parameters and noninvasive blood pressure between Friesian horses and Warmblood horses

Background: Aortic rupture is more common in Friesians compared to Warmbloods, which might be related to differences in arterial wall composition and, as such, arterial wall stiffness (AWS). Currently, nothing is known about differences in AWS between these breeds. Objectives: Comparison of AWS parameters and noninvasive blood pressure between Friesians and Warmbloods. Animals: One hundred one healthy Friesians and 101 age-matched healthy Warmbloods. Methods: Two-dimensional and pulsed-wave Doppler ultrasound examination was performed of the aorta, common carotid artery, and external iliac artery to define local and regional AWS parameters. Regional aortic AWS was estimated using aortic-to-external iliac artery pulse wave velocity (PWVa-e) and carotid-to-external iliac artery pulse wave velocity (PWVc-e). Noninvasive blood pressure and heart rate were recorded simultaneously. Results: Systolic, diastolic, and mean arterial blood pressure and pulse pressure were significantly higher in Friesians compared to Warmbloods. No significant difference in heart rate was found. Most local AWS parameters (diameter change, compliance coefficient, distensibility coefficient) were significantly lower in Friesians compared to Warmbloods, indicating a stiffer aorta in Friesians. This difference could be confirmed by the regional stiffness parameters. A higher PWVa-e and PWVc-e was found in Friesians. For the cranial and caudal common carotid artery and external iliac artery, most local AWS parameters were not significantly different. Conclusions and clinical importance: Results indicate that aortic AWS differs between Friesian and Warmblood horses. Friesians seem to have a stiffer aorta, which might be related to the higher incidence of aortic rupture in Friesians

Reference values for 2‐dimensional and M‐mode echocardiography in Friesian and Warmblood horses

Background Echocardiographic reference intervals for Friesian horses are poorly described. Objectives To obtain reference intervals for echocardiographic measurements in Friesians and compare these with Warmbloods. Animals One hundred healthy adult Friesians and 100 healthy adult Warmblood horses. Methods Cross-sectional study. Two-dimensional and M-mode echocardiographic images were obtained. Echocardiographic measurements, including size, area, and volumetric measurements of left atrium, left and right ventricle, aorta, and pulmonary artery, were performed. Measurements were compared between the 2 breeds using an independent samples t test with Bonferroni correction for multiple comparisons. Results Reference ranges for standard echocardiographic measurements in Friesians were obtained. Several left ventricular measurements were significantly smaller in Friesians compared to Warmbloods, such as the left ventricular end-diastolic volume using the 4-chamber modified Simpsons' method (99.85% confidence interval for the difference [CI] = -245 to -63). Also the right ventricular end-diastolic and peak-systolic internal diameter were smaller in Friesians (99.85% CI = -1.33 to -0.6 and 99.85% CI = -1.54 to -0.76, respectively). Fractional shortening (99.85% CI = 0.61-6) and ejection fraction (99.85% CI = 0.21-4.6) were significantly larger. No structural effects of systemic hypertension, such as concentric hypertrophy, were detected. Conclusions and Clinical Importance Our study provides reference intervals for echocardiographic measurements in Friesians useful in a clinical setting. In general, the left ventricular dimensions in Friesians were significantly smaller compared to Warmbloods, emphasizing the need for breed-specific reference intervals

Equine 3D electro-anatomical mapping in sinus rhythm elucidates the electrocardiogram and cardiac electrical activation pattern

Understanding the depolarisation pattern of the equine heart under normal physiological conditions, and its relationship to the surface electrocardiogram (ECG), is of uppermost importance before any further research can be done about the pathophysiology of complex arrhythmias. The purpose was to use a 3D electro-anatomical mapping system under general anaesthesia to evaluate the qualitative and quantitative atrial and ventricular depolarisation patterns and correlation with the surface ECG in 7 healthy horses in sinus rhythm. Bipolar activation maps of the endocardium were analysed. The first atrial activation was located at the height of the crista terminalis. Only one interatrial conduction pathway was recognised. The first and second P wave deflections represented the right and left atrial depolarisation, respectively. His bundle electrograms could be recorded in 5 out of 7 horses. Left ventricular activation (Fig. 1 to 3) started at the mid septum, right ventricular activation apically from the supraventricular crest. This was followed by separate depolarisations at the height of the mid free wall. Further ventricular depolarisation occurred in an explosive pattern. Electrically active tissue could be found in all pulmonary veins. In contrast to findings of previous studies, all parts of the ventricular depolarisation contributed to the surface ECG QRS complex. This study provides a reference for the normal sinus impulse endocardial propagation pattern and for conduction velocities in equine atria and ventricles. This information allows to improve ECG reading and develop better recording techniques, such as new 12-lead ECG configurations, in horses

QRS morphology changes depending on site of ventricular pacing during high resolution 3D electro-anatomical mapping in adult horses : preliminary results

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First successful radiofrequency ablation of focal atrial tachycardia in a horse guided by a high density 3D electro-anatomical mapping system (Rhythmia®)

Transvenous electrical cardioversion (TVEC) has a 95% success rate for cardioversion of atrial tachyarrhythmia but recurrence rate is about 35%. A 5-year-old showjumper stallion with regular atrial tachyarrhythmia was treated successfully with TVEC twice but showed early recurrence each time. An electrophysiological study suggested a right sided atrial tachycardia and the option for ablation was taken. In the standing horse, a decapolar catheter and two TVEC catheters, in case atrial fibrillation would occur during the procedure, were inserted in the left jugular vein and placed in the coronary sinus, right atrium and left pulmonary artery, respectively. Subsequently, under general anesthesia, an electro-anatomical mapping catheter (Intellamap Orion, Boston Scientific) was inserted into the right jugular vein and used to create a 3D electro-anatomical map (Rhythmia, Boston Scientific) of right atrium and venae cavae. Activation mapping, whereby the coronary sinus signal served as time reference, revealed a focal atrial tachycardia with a cycle length of 400ms with earliest activity at the caudodorsal interatrial wall. An ablation catheter (Intellanav OI, Boston Scientific) was guided towards the site of earliest activation using the Rhythmia mapping system and targeted for ablation. During the 5th application (temperature-controlled 60W, maximal temperature 60°C), the atrial tachycardia terminated and became non-inducible. Total ablation time was 366 seconds. Recovery was uneventful. This is the first time that the exact origin of an atrial arrhythmia is identified by 3D electro-anatomical mapping and is successfully treated by radiofrequency ablation. This study proves that both techniques are technically feasible in adult horses

Atrial fibrillatory rate as predictor of recurrence of atrial fibrillation in horses treated medically or with electrical cardioversion

Background The recurrence rate of atrial fibrillation (AF) in horses after cardioversion to sinus rhythm (SR) is relatively high. Atrial fibrillatory rate (AFR) derived from surface ECG is considered a biomarker for electrical remodelling and could potentially be used for the prediction of successful AF cardioversion and AF recurrence. Objectives Evaluate if AFR was associated with successful treatment and could predict AF recurrence in horses. Study design Retrospective multicentre study. Methods Electrocardiograms (ECG) from horses with persistent AF admitted for cardioversion with either medical treatment (quinidine) or transvenous electrical cardioversion (TVEC) were included. Bipolar surface ECG recordings were analysed by spatiotemporal cancellation of QRST complexes and calculation of AFR from the remaining atrial signal. Kaplan-Meier survival curve and Cox regression analyses were performed to assess the relationship between AFR and the risk of AF recurrence. Results Of the 195 horses included, 74 received quinidine treatment and 121 were treated with TVEC. Ten horses did not cardiovert to SR after quinidine treatment and AFR was higher in these, compared with the horses that successfully cardioverted to SR (median [interquartile range]), (383 [367-422] vs 351 [332-389] fibrillations per minute (fpm), P < .01). Within the first 180 days following AF cardioversion, 12% of the quinidine and 34% of TVEC horses had AF recurrence. For the horses successfully cardioverted with TVEC, AFR above 380 fpm was significantly associated with AF recurrence (hazard ratio = 2.4, 95% confidence interval 1.2-4.8, P = .01). Main limitations The treatment groups were different and not randomly allocated, therefore the two treatments cannot be compared. Medical records and the follow-up strategy varied between the centres. Conclusions High AFR is associated with failure of quinidine cardioversion and AF recurrence after successful TVEC. As a noninvasive marker that can be retrieved from surface ECG, AFR can be clinically useful in predicting the probability of responding to quinidine treatment as well as maintaining SR after electrical cardioversion