Designing Flipped Classrooms to Enhance Learning in the Clinical Skills Laboratory.

Flipped classroom is an educational technique in which content is delivered online for students to study at their own pace in preparation for in-class learning. Benefits include increased flexibility, enhanced student engagement and satisfaction, and more effective use of time spent during face-to-face teaching. However, the development and implementation of flipped classroom teaching are also associated with challenges, including time required to develop learning materials and getting students to engage with the preparatory work. This teaching tip describes a structured approach to designing and implementing the flipped classroom approach for clinical skills to allow a greater focus on practicing the hands-on skills and the provision of feedback during the laboratory session. First, the rationale for flipping the classroom and the expected benefits should be considered. On a practical level, decisions need to be made about what to include in the flipped component, how it will complement the face-to-face class, and how the resources will be created. In the design phase, adopting a structured template and aligning with established pedagogical principles is helpful. A well-designed flipped classroom motivates learners by including different elements such as quality educational media (e.g., videos), the opportunity to self-assess, and well-defined connections to relevant knowledge and skills. Student engagement with the flipped material can be promoted through different strategies such as clear communication to manage student expectations and adapting the delivery of the face-to-face component. Finally, gathering feedback and evaluating the initiative are important to inform future improvements.

Practical Tips for Setting Up and Running OSCEs.

Objective structured clinical examinations (OSCEs) are used to assess students' skills on a variety of tasks using live animals, models, cadaver tissue, and simulated clients. OSCEs can be used to provide formative feedback, or they can be summative, impacting progression decisions. OSCEs can also drive student motivation to engage with clinical skill development and mastery in preparation for clinical placements and rotations. This teaching tip discusses top tips for running an OSCE for veterinary and veterinary nursing/technician students as written by an international group of authors experienced with running OSCEs at a diverse set of institutions. These tips include tasks to perform prior to the OSCE, on the day of the examination, and after the examination and provide a comprehensive review of the requirements that OSCEs place on faculty, staff, students, facilities, and animals. These tips are meant to assist those who are already running OSCEs and wish to reassess their existing OSCE processes or intend to increase the number of OSCEs used across the curriculum, and for those who are planning to start using OSCEs at their institution. Incorporating OSCEs into a curriculum involves a significant commitment of resources, and this teaching tip aims to assist those responsible for delivering these assessments with improving their implementation and delivery.

Development of Surgical Competence in Veterinary Students Using a Flipped Classroom Approach.

Clinical skills laboratory (CSL) training was recently introduced in the renewed veterinary curriculum at Ghent University, using models and simulators for teaching practical skills. However, time in the CSL is restricted due to the large number of students combined with limited availability of personnel. Therefore, a flipped classroom (FC) model was introduced to maximize learning experiences. The goal of the present study was to evaluate the effect of flipped classroom CSL training on students' self-efficacy and practical surgical skills. Flipped classroom CSL training was implemented for the third-year pre-clinical students (n = 196) in the 6-year veterinary medicine program. Prior to CSL sessions, students studied online 'learning paths,' including text, pictures, videos of the skills, links to background information, a forum, and a compulsory pre-class quiz. A pre- and post-test were administered before and after flipped classroom CSL training. The tests consisted of a self-efficacy scale consisting of 20 items and an objective structured clinical examination (OSCE) test of surgical skills performance. Flipped classroom CSL training resulted in significantly higher self-efficacy (score/100, pre-test 55 ± 14 vs. post-test 83 ± 8, p< .001) and surgical skills performance (score/20, pre-test 5 ± 3 vs. post-test 17 ± 3, p< .001). In conclusion, this study demonstrated the feasibility and value of implementing a flipped classroom approach in combination with CSL training.

Pericardial Disease, Myocardial Disease, and Great Vessel Abnormalities in Horses.

Pericardial, myocardial, and great vessel diseases are relatively rare in horses. The clinical signs are often nonspecific and vague, or related to the underlying cause. Physical examination usually reveals tachycardia, fever, venous distension or jugular pulsation, a weak or bounding arterial pulse, ventral edema, and abnormal cardiac auscultation such as arrhythmia, murmur, or muffled heart sounds. The prognosis depends on the underlying cause and the disease progression, and ranges from full recovery to poor prognosis for survival. This article focuses on the etiology, diagnosis, prognosis, and treatment of pericarditis, pericardial mass lesions, myocarditis, cardiomyopathy, and great vessel aneurysm or rupture.

Measurement variability of right atrial and ventricular monophasic action potential and refractory period measurements in the standing non-sedated horse.

BACKGROUND: In human and veterinary medicine, monophasic action potential (MAP) analysis and determination of local refractory periods by contact electrode technique gives valuable information about local cardiac electrophysiological properties. It is used to investigate dysrhythmias and the impact of drugs on the myocardium. Precise measurement of total MAP duration is difficult, therefore the MAP duration is usually determined at a repolarization level of 90% (APD90). Until now, no studies are published about the feasibility of this technique in the standing non-sedated horse. In 6 healthy Warmblood horses, on two different days, an 8F quadripolar contact catheter was passed through a jugular introducer sheath and placed under ultrasound guidance at the level of the intervenous tubercle or right atrial free wall (RA), and in the right ventricular apex (RV) to record the MAP. The MAP amplitude and APD90 were measured at a resting sinus rhythm (heart rate of 30-42 bpm) and at pacing cycle lengths (PCL) of 1000 and 600 ms. The effective refractory period (ERP) was determined at PCL of 1000 and 600 ms. RESULTS: The overall mean (±SD) APD90 (rest), APD90 (1000) and APD90 (600) were 263 ± 39 ms, 262 ± 41 ms, 236 ± 47 ms for the RA and 467 ± 23 ms, 412 ± 38 ms, 322 ± 29 ms for the RV. The mean ERP1000 and ERP600 were 273 ± 24 ms and 256 ± 22 ms for the RA and 386 ± 40 ms and 293 ± 30 ms for the RV. The measurement variability for the amplitude, APD90 and ERP measurements in the RA ranged between 36 and 44, 9-22 and 7-8%, respectively. The measurement variability for the amplitude, APD90 and ERP measurements in the RV ranged between 49 and 66, 6-7 and 10-12%, respectively. CONCLUSIONS: RA and RV MAP duration and ERP can be obtained by a contact electrode in standing non-sedated horses. The measurement variability varies with catheter location.

Flemish equine veterinarians' perceptions on the use of and client communication about complementary and alternative veterinary medicine.

BACKGROUND: Complementary and alternative veterinary medicine (CAVM) is increasingly popular in horses. As CAVM usage could have risks, client-veterinarian communication about CAVM is crucial. OBJECTIVES: Evaluating equine veterinarians' attitude towards CAVM, their CAVM usage and veterinarian-client communication about CAVM. STUDY DESIGN: Cross-sectional study. METHOD: A telephone survey was conducted among equine veterinarians providing ambulatory care on a daily or weekly basis. The first section of the survey included questions about the veterinarians' attitude towards CAVM and their CAVM usage. The second section focused on veterinary-client communication about CAVM. RESULTS: When herbs are included as CAVM modality, 83% of the participants applied CAVM. Nighty-eight percent had already communicated with horse owners about CAVM and 81% agreed to be open to talk about CAVM. However, 95% agreed that sometimes CAVM usage takes place without disclosure to the veterinarian. The majority of participants communicated about CAVM on a weekly (40%) or daily (22%) basis, most often in person during consultations (99%) or via phone (32%). The median percentage of conversations about CAVM initiated by the owner was 50% (range 50%-80%). When the veterinarian initiated the conversation, this was usually by mentioning it as a treatment option, mostly in addition to conventional treatments. Some participants directly asked about CAVM use in the information-gathering phase. MAIN LIMITATIONS: A convenience sample was used due to lack of data on the number of equine veterinarians in Flanders. Potential favourability bias with higher participation of veterinarians interested in CAVM. CONCLUSION: Equine veterinarians generally had a positive attitude towards CAVM use, although this depended on the specific modality. Veterinarian-client communication about CAVM occurs frequently in ambulatory care. An open dialogue with horse owners about CAVM is important to provide information about CAVM and thus enable them to make informed decisions concerning CAVM usage, together with their veterinarian.

INTRODUCTION/CONTEXTE: La médecine complémentaire et alternative (CAVM) est de plus en plus populaire chez les équins. Comme l'utilisation de la CAVM peut entrainer des risques, la communication entre le vétérinaire et le client à propros de la CAVM est cruciale. OBJECTIFS: Évaluer l'attitude des vétérinaires équins par rapport à la CAVM, leur utilisation de la CAVM et leur communication aux clients en lien avec la CAVM. TYPE D'ÉTUDE: Étude transversale. MÉTHODES: Un sondage téléphonique des vétérinaires équins fournissant un service ambulatoire journalier ou hebdomadaire a été fait. La première partie du sondage incluait l'attitude des vétérinaires vis­à­vis la CAVM et leur usage de la CAVM. La seconde partie se concentrait sur la communication vétérinaire­client à propos de la CAVM. RÉSULTATS: Lorsque les herbes étaient incluses en tant que modalités de la CAVM, 83% des participants appliquaient la CAVM. Quatre­vingt­dix­huit pourcents avaient déjà parlé de la CAVM avec des propriétaires de chevaux et 81% étaient ouvert à l'idée d'en parler à leur client. Par contre, 95% étaient d'accord pour dire que la CAVM est parfois utilisée sans le mentionner au client. La majorité des participants parlaient de la CAVM sur une base hebdomadaire (40%) ou journalière (22%), le plus souvent durant les rendez­vous (99%) ou par téléphone (32%). Le pourcentage médian de conversations initiées par les propriétaires, à propos de la CAVM était de 50% (étendu 50­80%). Lorsque le vétérinaire initiait la conversation à ce sujet, c'était le plus souvent en mentionnant la CAVM comme option de traitement, plus particulièrement comme étant un ajout aux traitements conventionnels. Certains participants ont demandé de l'information directement à propos de la CAVM durant la phase de récolte de l'information. LIMITES PRINCIPALES: Un échantillon de convenance a été utilisé en raison du manque de données par rapport au nombre de vétérinaires équins dans les Flandres. Biais favorable possible en cas de participation plus élevée des vétérinaires intéressés par la CAVM. CONCLUSIONS: Les vétérinaires équins ont généralement une attitude positive par rapport à la CAVM, parfois dépendant spécifiquement de la modalité de traitement. Les communications vétérinaire­client à propos de la CAVM se produisent très fréquemment en pratique ambulatoire. Un discours ouvert avec les propriétaires de chevaux à propos de la CAVM est important afin de fournir de l'information sur la CAVM et de ce fait, leur permettre de faire une décision éclairée en ce qui à trait à l'utilisation de la CAVM, en accord avec leur vétérinaire.

Congenital heart defects in Arabian horses and the prospects of genetic testing: A review.

Congenital heart defects (CHDs) can have profound and potentially life-threatening consequences on horses' health and performance capability. While CHDs are rare in the general horse population, the Arabian breed is disproportionately overrepresented and thus is widely suspected to be genetically predisposed. This review discusses the most common CHDs in Arabian horses, including ventricular septal defect (VSD), tetralogy of Fallot (TOF), patent duct arteriosus (PDA), tricuspid valve atresia (TVA) and atrial septal defect (ASD). This review also explores how future research into the genetic factors that likely underpin many CHDs can revolutionise the way these disorders are managed in Arabian horses.

Effect of physiological and pharmacological stress on heart rate, blood pressure, and echocardiographic measurements in healthy Warmblood horses.

BACKGROUND: Echocardiographic measurements are important prognostic indicators but might be influenced by heart rate and blood pressure. This is particularly important when comparing repeated examinations. HYPOTHESIS: To determine the effect of physiological stress at mildly increased heart rates and pharmacological challenge using IV administration of N-butylscopolammonium bromide and metamizol sodium on heart rate, blood pressure, and echocardiographic measurements. ANIMALS: Twenty healthy Warmblood horses. METHODS: Randomized crossover study. Horses were examined echocardiographically by 2-dimensional, M-mode, pulsed wave (PW) Doppler, and PW tissue Doppler imaging with simultaneous ECG recording and noninvasive blood pressure measurements during rest, physiological stress, and pharmacological challenge. Cardiac dimensions and functions were measured by a blinded observer. Data were analyzed using repeated-measures analysis of variance. RESULTS: Mean heart rate and arterial blood pressure were significantly higher during physiological stress (46 ± 2 bpm, 93 ± 16 mm Hg) and pharmacological challenge (62 ± 13 bpm, 107 ± 17 mm Hg) compared with rest (34 ± 3 bpm, 86 ± 12 mm Hg; P < .05). Compared with rest, physiological stress resulted in increased left atrial fractional area change (34.3 ± 7.5 vs 27.3 ± 5.1%; P = .01) and left ventricular late diastolic radial wall motion velocity (13 ± 3 vs 10 ± 2 cm/s; P = .01) but had no significant effect on most other echocardiographic variables. Compared with rest, pharmacological challenge led to significantly decreased left atrial and diastolic ventricular dimensions (left ventricular internal diameter: 10.3 ± 0.9 vs 10.7 ± 0.8 cm; P = .01), increased aortic and pulmonary diameters, and ventricular wall thickness. CONCLUSIONS AND CLINICAL IMPORTANCE: Physiological stress at mildly increased heart rates significantly enhanced atrial pump function. Larger heart rate and blood pressure increases during pharmacological challenge resulted in altered cardiac dimensions. This should be taken into account when evaluating echocardiographic measurements at increased heart rates.

Feasibility of transthoracic echocardiographic guidance for multicatheter electrophysiological mapping studies in horses.

BACKGROUND: Improved characterization of arrhythmias is based on minimally invasive catheterizations. However, these catheterizations have been poorly explored in horses because apart from 3-dimensional (3D) mapping systems, continuous guidance of the catheter's position with adequate detail is difficult using current imaging modalities. HYPOTHESIS: Position multiple electrophysiology catheters simultaneously at predetermined strategical positions in the heart using transthoracic echocardiographic guidance. ANIMALS: Eight adult healthy horses. METHODS: Observational study. Two electrophysiological studies were performed: 1 procedure with catheters positioned in the right heart in the standing sedated horse and 1 procedure under general anesthesia with catheters positioned in the left heart. Except for the coronary sinus catheter, each catheter positioning was simultaneously guided by right-parasternal transthoracic echocardiography and 3D electro-anatomical mapping. RESULTS: For each catheter position, a central imaging plane was taken as the starting point, after which the imaging probe was shifted, rotated, and angulated to visualize the catheter over its entire length, including its distal electrode. Catheter positionings in the right heart and left ventricle were successfully guided in the majority of the horses whereas catheter positionings in the left atrium, and especially the pulmonary veins, were challenging to guide echocardiographically. CONCLUSIONS AND CLINICAL IMPORTANCE: Ultrasound guidance of catheters to specific positions useful for electrophysiological mapping was feasible in the right heart and left ventricle but challenging for the left atrium. This approach creates a perspective for minimally invasive arrhythmia diagnosis without the need for a 3D mapping system. Left parasternal views and intracardiac echocardiography might provide better guidance for left atrial positions.

Development of an atrial transseptal puncture procedure in horses to access the left heart: An ultrasound-guided jugular vein and transhepatic approach.

BACKGROUND: Radiofrequency ablation has been successfully applied to treat right atrial arrhythmias in horses. Ablation of left-sided arrhythmias requires a retrograde transarterial approach which is complicated. In human medicine, the left atrium is accessed through transseptal puncture (TSP) of the fossa ovalis (FO) using a caudal approach via the femoral vein. OBJECTIVES: To develop a zero fluoroscopy TSP technique for horses using a jugular vein (cranial) and transhepatic (caudal) approach. STUDY DESIGN: In vivo experimental study. METHODS: Transseptal puncture was performed in 18 horses admitted for euthanasia and donated for scientific research under general anaesthesia: using a jugular vein approach (10 horses), a transhepatic approach (2 horses) or both (6 horses). Radiofrequency energy was applied on a guidewire to perforate the FO and allow sheath advancement under intracardiac and transthoracic echocardiographic guidance. Puncture lesions were inspected post-mortem. RESULTS: Transseptal puncture was successful in 17/18 horses, of which 15/16 jugular vein approaches and 5/8 transhepatic approaches. Failure was due to technical malfunction, inability to advance the guidewire toward the heart and inability to advance the sheath through the FO. Intracardiac echocardiography was essential to safely guide the puncture process. Atrial arrhythmias caused by the TSP occurred in 13/18 horses. Puncture lesions were found in the right atrium in the FO region, and left atrium ventral to pulmonary vein ostium III. MAIN LIMITATIONS: Because in several horses two approaches were tested consecutively, it cannot be excluded that the second TSP was performed at the previous puncture site. Due to the developmental nature of the study the approaches were not randomised and did not allow comparison. CONCLUSION: Transseptal puncture is feasible in horses using ultrasound guidance and allows for electrophysiological exploration of the left heart. Further studies are needed to evaluate post-operative follow-up.

Intracardiac ultrasound-guided transseptal puncture in horses: Outcome, follow-up, and perioperative anticoagulant treatment.

BACKGROUND: Cardiac catheterizations in horses are mainly performed in the right heart, as access to the left heart traditionally requires an arterial approach. Transseptal puncture (TSP) has been adapted for horses but data on follow-up and closure of the iatrogenic atrial septal defect (iASD) are lacking. HYPOTHESIS/OBJECTIVES: To perform TSP and assess postoperative complications and iASD closure over a minimum of 4 weeks. ANIMALS: Eleven healthy adult horses. METHODS: Transseptal puncture was performed under general anesthesia. Serum cardiac troponin I concentrations were measured before and after puncture. Weekly, iASD closure was monitored using transthoracic and intracardiac echocardiography. Relationship between activated clotting time and anti-factor Xa activity during postoperative enoxaparin treatment was assessed in vitro and in vivo. RESULTS: Transseptal puncture was successfully achieved in all horses within a median duration of 22 (range, 10-104) minutes. Balloon dilatation of the puncture site for sheath advancement was needed in 4 horses. Atrial arrhythmias occurred in 9/11 horses, including atrial premature depolarizations (N = 1), atrial tachycardia (N = 5), and fibrillation (N = 3). Serum cardiac troponin I concentrations increased after TSP, but remained under the reference value in 10/11 horses. Median time to iASD closure was 14 (1-35) days. Activated clotting time correlated with anti-factor Xa activity in vitro but not in vivo. CONCLUSIONS AND CLINICAL IMPORTANCE: Transseptal puncture was successfully performed in all horses. The technique was safe and spontaneous iASD closure occurred in all horses. Clinical application of TSP will allow characterization and treatment of left-sided arrhythmias in horses.

Surveying dog owners' use and understanding of, and communication with veterinarians about, complementary and alternative veterinary medicine.

BACKGROUND: Complementary and alternative veterinary medicine (CAVM) seems to be gaining acceptance by pet owners. Client-veterinarian communication about CAVM is important to explore client perceptions and facilitate open exchange of ideas between owners and veterinarians. METHODS: This study includes an online, cross-sectional survey of dog owners to evaluate CAVM use and client-veterinarian communication about CAVM. Based on the extended theory of planned behaviour, factors influencing the intention to use CAVM were evaluated. RESULTS: Past CAVM use was reported by 45.3% clients based on 1000 valid surveys. The attitude towards CAVM was generally positive. Perceived knowledge about CAVM positively predicted perceived behavioural control and attitude towards CAVM. Both were the strongest predictors of future CAVM use. Around 45.7% of clients had already talked to their veterinarian about CAVM. This conversation was mainly initiated by the owner (66.3%). Owners expected the veterinarian to have knowledge about CAVM (91.5%) and offer referral (71.5%). LIMITATIONS: The limitation is difficulty in classifying and defining CAVM modalities. CONCLUSIONS: Owners' perceived behavioural control and attitude towards CAVM predict CAVM use. Failure to engage in a conversation about CAVM hampers clients to partner with veterinarians to discuss the treatment approach and maximise patient outcome. The veterinarian plays an essential role in providing objective accurate information about CAVM.

Three-dimensional electro-anatomical mapping and radiofrequency ablation as a novel treatment for atrioventricular accessory pathway in a horse: A case report.

We describe the diagnosis and treatment of an atrioventricular accessory pathway (AP) in a horse using 3-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA). During routine evaluation of the horse, intermittent ventricular pre-excitation was identified on the ECG, characterized by a short PQ interval and abnormal QRS morphology. A right cranial location of the AP was suspected from the 12-lead ECG and vectorcardiography. After precise localization of the AP using 3D EAM, ablation was performed and AP conduction was eliminated. Immediately after recovery from anesthesia an occasional pre-excited complex still was observed, but a 24-hour ECG and an ECG during exercise 1 and 6 weeks after the procedure showed complete disappearance of pre-excitation. This case shows the feasibility of 3D EAM and RFCA to identify and treat an AP in horses.

Defining Hemodynamic Significance of Renal Artery Stenosis: Insights From a Porcine Model of Graded Renal Artery Stenosis.

RATIONALE AND OBJECTIVES: To investigate the renal pressure-flow relationship and its relation to renin release, because the renal perfusion pressure below which renal flow starts to decline and renin secretion is upregulated is unclear. MATERIALS AND METHODS: A porcine model of graded unilateral renal artery stenosis was created. The severity of the stenosis was expressed as the ratio between distal renal pressure (Pd) and aortic pressure (Pa). Pd and renal flow velocity were continuously measured using a combined pressure-flow wire (Combowire®). Hemodynamic measurements and blood sampling for renin, angiotensin and aldosterone were performed in baseline conditions and during progressive balloon inflation in the renal artery leading to Pd decrease per 5% increment. Resistive index (RI) was computed as (1 - (End Diastolic V/Peak Systolic V))*100. RESULTS: For a 5% decrease in renal perfusion pressure (95% of aortic pressure or 5% decrease compared to Pa), peak systolic velocity started to decrease. A significant decrease in average peak flow velocity was observed when distal renal perfusion pressure decreased by 25% and was associated with activation of ipsilateral renin secretion. The RI decreased already for minimal changes in Pd/Pa ratio. CONCLUSION: In an animal model of unilateral graded renal artery stenosis, a 25% decrease in perfusion pressure results in a significant decrease in distal renal flow, causing upregulation of renin secretion.

Successful caudal vena cava and pulmonary vein isolation in healthy horses using 3D electro-anatomical mapping and a contact force-guided ablation system.

BACKGROUND: Recently, treatment of equine atrial tachycardia by three-dimensional electro-anatomical mapping (3D EAM) and radiofrequency catheter ablation (RFCA) has been described. Myocardial sleeves in the caudal vena cava and pulmonary veins are a potential trigger for initiation and perpetuation of atrial tachycardia and atrial fibrillation in the horse. Isolation of these myocardial sleeves by RFCA may be an effective treatment for these arrhythmias. OBJECTIVES: To describe the feasibility of 3D EAM and RFCA to isolate caudal vena cava and pulmonary veins in adult horses using 3D mapping and a contact force (CF)-guided ablation system. STUDY DESIGN: In vivo experiments. METHODS: 3D EAM and RFCA was performed in five horses without cardiovascular disease under general anaesthesia, using the CF-guided system CARTO®3. Point-by-point RFCA aimed for isolation of caudal vena cava and pulmonary veins. Radiofrequency energy was delivered in power-controlled mode with a target power of 45 W, CF between 10 and 15 g and 30 mL/min irrigation rate, until an ablation-index of 450-500 was reached. RESULTS: In the right atrium, myocardial sleeves of the caudal vena cava were isolated (n = 5). In the left atrium, isolation of ostium II (n = 3), ostium III (n = 1) and ostium I, II and III en bloc (n = 1) was performed. Successful isolation was confirmed by entrance and exit block. MAIN LIMITATIONS: Horses were euthanised at the end of the procedure, so long term effects such as potential reconnection of isolated veins could not be studied. CONCLUSIONS: This is the first description of 3D EAM and RFCA with CARTO®3 in horses, thereby showing the technical feasibility and successful caudal vena cava and pulmonary vein isolation. CF measurement allowed monitoring of catheter-tissue contact, resulting in efficient acute lesion creation as confirmed by entrance and exit block. This is a promising treatment for cardiac arrhythmias in horses.

Echocardiographic Features of the Ductus Arteriosus and the Foramen Ovale in a Hospital-Based Population of Neonatal Foals.

The ductus arteriosus (DA) and foramen ovale (FO), including the septum primum (SP) and septum secundum (SS), are important structures in fetal circulation and are unexplored in neonatal equids. The objective of this study is to describe echocardiographic characteristics in a hospital-based population of neonatal foals. On days 2, 5 and 10 after parturition, cardiac ultrasound was performed, and clinical data were collected in healthy and diseased Warmblood foals. Fifty healthy (n = 15) and diseased (n = 35) Warmblood foals were examined. A left-sided and right-sided holosystolic murmur was audible in 98% (n = 42) and 51% (n = 22), respectively, on day 2; in 81% (n = 25) and 19% (n = 6) on day 5; and in 44% (n = 4) and 11% (n = 1) on day 10. The median grade of the systolic murmurs was higher when the DA was open. Flow through the DA could be visualized with color flow and continuous wave (CW) Doppler from the left parasternal long-axis view of the pulmonary artery in 40/43 foals on day 2, 9/31 foals on day 5 and 2/9 foals on day 10. The DA diameter was 2 ± 1 mm on day 2, 2 ± 1 mm on day 5 and 1 mm on day 10. The thickness of both septa of the FO was similar. The SP fluttered into the left atrium at all ages, but the maximal distance between the SP and SS decreased over time. In conclusion, cardiac murmurs, a patent DA and fluttering FO are frequent findings in neonatal foals. While these findings are probably physiological, the clinical importance needs to be further elucidated.

Three-dimensional and catheter-based intracardiac echocardiographic characterization of the interatrial septum in 2 horses with suspicion of a patent foramen ovale.

This case report describes the 2-dimensional transthoracic (2D-TTE), 3-dimensional transthoracic (3D-TTE) and intracardiac echocardiographic (ICE) characterization of the fossa ovalis region in 2 horses. The first case was presented for poor performance and showed an anechoic zone in the interatrial septum on 2D-TTE. Based on 3D-TTE a deepened fossa ovalis could be identified and using ICE the presence of an interatrial shunt could be excluded. The second case was referred for a cardiac murmur and the presence of turbulent flow in and around the interatrial septum on 2D-TTE color flow Doppler. The complementary use of 2D-TTE, 3D-TTE, and ICE allowed detailed characterization of a patent foramen ovale, with evidence of a left-to-right shunt in a dorsocranial to ventrocaudal direction with limited hemodynamic implications. These 2 cases underline the feasibility of 3D-TTE and ICE in horses and especially show the added value of ICE in a clinical setting.

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

BACKGROUND: Atrial 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. OBJECTIVES: To describe the feasibility of 3D electro-anatomical mapping and radiofrequency catheter ablation to characterize and treat sustained AT in horses. ANIMALS: Nine horses with sustained AT. METHODS: Records from horses with sustained AT referred for radiofrequency ablation at Ghent University were reviewed. RESULTS: The 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 IMPORTANCE: Differentiation 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.

An Exploratory Study on Vectorcardiographic Identification of the Site of Origin of Focally Induced Premature Depolarizations in Horses, Part I: The Atria.

In human cardiology, the anatomical origin of atrial premature depolarizations (APDs) is derived from P wave characteristics on a 12-lead electrocardiogram (ECG) and from vectorcardiography (VCG). The objective of this study is to differentiate between anatomical locations of APDs and to differentiate APDs from sinus rhythm (SR) based upon VCG characteristics in seven horses without cardiovascular disease. A 12-lead ECG was recorded under general anaesthesia while endomyocardial atrial pacing was performed (800−1000 ms cycle length) at the left atrial free wall and septum, right atrial free wall, intervenous tubercle, as well as at the junction with the cranial and caudal vena cava. Catheter positioning was guided by 3D electro-anatomical mapping and transthoracic ultrasound. The VCG was calculated from the 12-lead ECG using custom-made algorithms and was used to determine the mean electrical axis of the first and second half of the P wave. An ANOVA for spherical data was used to test if the maximal directions between each paced location and the maximal directions between every paced location and SR were significantly (p < 0.05) different. Atrial pacing data were not available from the LA septum in three horses, the intervenous tubercle in two horses, and from the LA free wall in one horse. The directions of the maximal electrical axes showed significant differences between all paced locations and between the paced locations and SR. The current results suggest that VCG is useful for identifying the anatomical origin of an atrial ectopy.

An Exploratory Study on Vectorcardiographic Identification of the Site of Origin of Focally Induced Premature Depolarizations in Horses, Part II: The Ventricles.

In human cardiology, the anatomical origin of ventricular premature depolarizations (VPDs) is determined by the characteristics of a 12-lead electrocardiogram (ECG). Former studies in horses had contradictory results regarding the diagnostic value of the 12-lead ECG and vectorcardiography (VCG), which results were attributed to the different cardiac conduction system in this species. The objective of this study was to determine if the anatomical origin of pacing-induced VPDs could be differentiated in horses based upon VCG characteristics. A 12-lead ECG was recorded in seven horses under general anesthesia while right and left ventricular endomyocardial pacing was performed (800−1000 ms cycle length) at the apex, mid and high septum and mid and high free wall, and at the right ventricular outflow tract. Catheter positioning was guided by 3D electro-anatomical mapping and echocardiography. A median complex, obtained from four consecutive complexes, was calculated for each pacing location and sinus rhythm. The VCG was calculated from the 12-lead ECG-derived median complexes using custom-made algorithms and was used to determine the initial and maximum electrical axes of the QRS complex. An ANOVA for spherical data was used to test if VCGs between each paced location and between pacing and sinus rhythm were significantly (p < 0.05) different. The model included the radius, azimuth and elevation of each electrical axis. Pacing induced significantly different initial and maximum electrical axes between different locations and between pacing and sinus rhythm. The current results suggest that VCG is a useful technique to identify the anatomical origin of ventricular ectopy in horses.