Transvenous Electrical Cardioversion Research Articles

Transvenous Electrical Cardioversion of Equine Atrial Fibrillation: Patient Factors and Clinical Results in 72 Treatment Episodes

Transvenous electrical cardioversion (TVEC) has been developed for treatment of atrial fibrillation (AF) in horses. The relationship among patient variables, treatment response, and outcome in a typical referral population has not been evaluated. Patient variables such as age, sex, weight, and duration of arrhythmia affect prognosis for response to treatment and the energy level at which cardioversion occurs. TVEC was applied to 72 episodes of lone AF in 63 client-owned performance horses, with the majority (54) being Standardbred racehorses. Catheterization of the right atrium (RA) and pulmonary artery (PA) through the jugular vein was used for electrode placement before horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energy levels until cardioversion was achieved or a maximum single-energy level of 300 J was reached (cumulative energy 50-1,960 J). A multivariate model was constructed to evaluate influence of patient factors on cardioversion energy. Cardioversion was achieved in 71 of 72 episodes (62 of 63 horses) at a mean energy of 165.43 +/- 8.75 J. Cardioversion energy was higher for females than for males, and for interaction terms, weight was negatively related to energy in females and positively related in males. Age was positively related to cardioversion energy in females. No relationship was identified between duration of arrhythmia before treatment and prognosis for response or cardioversion energy. TVEC is highly effective in the treatment of lone AF in horses. Although age and sex influence cardioversion energy level, duration of arrhythmia does not.

Transvenous electrical cardioversion of atrial fibrillation in six horses using custom made cardioversion catheters

Pharmacological conversion of atrial fibrillation (AF) to sinus rhythm in horses can be difficult. The objective of this study was to investigate the feasibility of transvenous electrical cardioversion with custom made catheters in eight horses, of which three had failed cardioversion using quinidine sulfate. Two cardioversion catheters and one pacing/sensing electrode were inserted via the right jugular vein and placed using ultrasound guidance into the left pulmonary artery, the right atrium and the right ventricle, respectively. Because immediate recurrence of AF was encountered in the second horse treated, pre-treatment with amiodarone was given to each of the remaining six horses. Induction of general anaesthesia was associated with dislocation of the cardioversion catheter in three horses, requiring a second catheterisation procedure. During general anaesthesia, biphasic R wave synchronised shocks of up to 360 J were delivered between both cardioversion electrodes. In six horses (75%), including two which had failed quinidine sulfate treatment, sinus rhythm was restored with a mean energy level of 295 ± 62 J. No side effects were observed. Blood analysis 3 h after cardioversion revealed normal parameters, including cardiac troponin I values. Transvenous electrical cardioversion of atrial fibrillation with custom made cardioversion catheters can be considered as a treatment option for atrial fibrillation in horses, especially when conventional drugs fail.

Management and complications of anesthesia for transvenous electrical cardioversion of atrial fibrillation in horses: 62 cases (2002–2006)

To describe management of anesthesia for transvenous electrical cardioversion (TVEC) in horses and report perianesthetic complications. Retrospective case series. 62 horses with atrial fibrillation and without underlying cardiac disease and 60 horses without atrial fibrillation. Medical records of horses with atrial fibrillation anesthetized for TVEC were reviewed, as were records of horses without atrial fibrillation anesthetized for magnetic resonance imaging (MRI). The TVEC group horses were compared with MRI group horses for incidence of intraoperative bradycardia and use of inotropic drugs. Data obtained included patient signalment, weight, duration of anesthesia, heart rate and arterial blood pressure during anesthesia, anesthetic drugs administered, mode of ventilation, perioperative complications, and quality of recovery. The TVEC group horses were > 1 year of age and were predominantly Standardbreds. The TVEC group horses underwent a total of 76 anesthetic episodes. For 40 (52.6%) anesthetic episodes, horses received xylazine only for premedication, and for 26 (34.2%) anesthetic episodes, horses received xylazine and butorphanol. Induction of anesthesia consisted of ketamine administration in various combinations with diazepam and guaifenesin for 74 (97.4%) anesthetic episodes and ketamine alone for 2 (2.6%). Bradycardia in horses was encountered during 15 of 76 (19.7%) anesthetic episodes. Minor signs of possible postanesthetic myopathy occurred following 6 (7.9%) anesthetic episodes. No significant difference was found between TVEC and MRI group horses regarding incidence of bradycardia and inotropic drug administration. Short-duration anesthesia for TVEC of atrial fibrillation in horses without underlying cardiac disease was a safe procedure.

Echocardiographic Evidence of Left Atrial Mechanical Dysfunction after Conversion of Atrial Fibrillation to Sinus Rhythm in 5 Horses

Background: Atrial contractile dysfunction occurs in some species after conversion of atrial fibrillation (AF) to normal sinus rhythm (NSR) but has not been reported in horses with naturally occurring AF. Hypothesis: Transthoracic echocardiography allows detection of left atrial (LA) mechanical dysfunction in horses after conversion of AF to NSR. Animals: Five Standardbreds with AF and 6 healthy Standardbreds of similar age, weight, and athletic condition were included in this study. Methods: Four horses were treated pharmacologically (quinidine), and 1 horse was treated by means of transvenous electrical cardioversion. Echocardiographic examinations were performed in normal horses (once) and in AF horses (24 hours and 72 hours after conversion to NSR) by means of 2‐dimensional echocardiography (2DE), transmitral flow Doppler, and tissue Doppler imaging (TDI) techniques. Echocardiographic indices of LA mechanical function were compared between normal horses and AF horses. Results: Two‐dimensional echocardiography and TDI indices of LA mechanical function revealed significant decreases in LA contractile function and LA reservoir function 24 hours after cardioversion. This decrease was no longer statistically significant 72 hours after cardioversion, but changes in echocardiographic variables between 24 and 72 hours varied among horses. Conclusions and Clinical Importance: LA contractile dysfunction can be evaluated in horses by use of 2DE, transmitral Doppler flow velocity profiles, and analyses of LA wall motion by TDI. The results of this study are consistent with AF‐induced atrial remodeling, although residual treatment effects or influence of underlying primary myopathy cannot be excluded.

Echocardiographic Evidence of Left Atrial Mechanical Dysfunction after Conversion of Atrial Fibrillation to Sinus Rhythm in 5 Horses

Atrial contractile dysfunction occurs in some species after conversion of atrial fibrillation (AF) to normal sinus rhythm (NSR) but has not been reported in horses with naturally occurring AF. Transthoracic echocardiography allows detection of left atrial (LA) mechanical dysfunction in horses after conversion of AF to NSR. Five Standardbreds with AF and 6 healthy Standardbreds of similar age, weight, and athletic condition were included in this study. Four horses were treated pharmacologically (quinidine), and 1 horse was treated by means of transvenous electrical cardioversion. Echocardiographic examinations were performed in normal horses (once) and in AF horses (24 hours and 72 hours after conversion to NSR) by means of 2-dimensional echocardiography (2DE), transmitral flow Doppler, and tissue Doppler imaging (TDI) techniques. Echocardiographic indices of LA mechanical function were compared between normal horses and AF horses. Two-dimensional echocardiography and TDI indices of LA mechanical function revealed significant decreases in LA contractile function and LA reservoir function 24 hours after cardioversion. This decrease was no longer statistically significant 72 hours after cardioversion, but changes in echocardiographic variables between 24 and 72 hours varied among horses. LA contractile dysfunction can be evaluated in horses by use of 2DE, transmitral Doppler flow velocity profiles, and analyses of LA wall motion by TDI. The results of this study are consistent with AF-induced atrial remodeling, although residual treatment effects or influence of underlying primary myopathy cannot be excluded.

How to perform transvenous electrical cardioversion in horses with atrial fibrillation

Electrical cardioversion of atrial fibrillation is a well-established technique for restoration of sinus rhythm in humans. While transthoracic cardioversion is more commonly used, transvenous electrical cardioversion (TVEC) has been reported as having higher efficacy at substantially lower energy levels. In horses, treatment of atrial fibrillation has essentially been limited to the administration of quinidine salts either orally or intravenously. TVEC provides an alternative to quinidine salts, especially for those animals in which quinidine is neither effective nor tolerated. The present report details this technique in horses, discusses possible complications of the procedure, and provides guidance for successful outcome. Still and video images are used to illustrate details with regard to TVEC techniques in horses. Please view supplemental material for the videos.

Transvenous Electrical Cardioversion of Equine Atrial Fibrillation Technical Considerations

Conventional treatment of equine atrial fibrillation (AF) involves administration of quinidine salts. Most uncomplicated cases respond to treatment, but pharmacologic cardioversion involves a range of adverse effects, and some horses are unable to tolerate medication. A study was undertaken to develop transvenous electrical cardioversion (TVEC) as an alternative treatment. Safety issues and catheter placement techniques with catheter-integrated cardioversion electrodes were investigated, and responses to shock application were evaluated. After the premortem catheterization of elective-euthanasia horses, no tissue abnormalities were detected at postmortem examination. To evaluate the response to the application of shocks and appropriate electrode positions, an electrical cardioversion of research horses in chronic AF was then attempted. After catheterization of the right atrium (RA) and pulmonary artery through the right jugular vein, horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energies until cardioversion was achieved or until a maximum energy of 300 J was reached. Five treatment events were applied to 3 horses, with cardioversion achieved in one of the treatment events. No adverse effects of cardioversion attempts or general anesthesia were observed. The procedure was then applied to 8 client-owned horses, with cardioversion achieved in 7. No adverse responses to appropriately delivered shocks were observed. No antiarrhythmic medications were administered to any horse at any stage. Catheter design and placement technique evolved throughout the study, with combined ultrasonography and pressure guidance proving most effective in achieving appropriate electrode placement. Results suggest TVEC, as applied in the present study, is a safe, effective, and realistic therapeutic option for equine AF.

Transvenous Electrical Cardioversion of Equine Atrial Fibrillation: Technical Considerations

Conventional treatment of equine atrial fibrillation (AF) involves administration of quinidine salts. Most uncomplicated cases respond to treatment, but pharmacologic cardioversion involves a range of adverse effects, and some horses are unable to tolerate medication. A study was undertaken to develop transvenous electrical cardioversion (TVEC) as an alternative treatment. Safety issues and catheter placement techniques with catheter-integrated cardioversion electrodes were investigated, and responses to shock application were evaluated. After the premortem catheterization of elective-euthanasia horses, no tissue abnormalities were detected at postmortem examination. To evaluate the response to the application of shocks and appropriate electrode positions, an electrical cardioversion of research horses in chronic AF was then attempted. After catheterization of the right atrium (RA) and pulmonary artery through the right jugular vein, horses were placed under general anesthesia. Biphasic, truncated exponential shock waves were delivered at incremental energies until cardioversion was achieved or until a maximum energy of 300 J was reached. Five treatment events were applied to 3 horses, with cardioversion achieved in one of the treatment events. No adverse effects of cardioversion attempts or general anesthesia were observed. The procedure was then applied to 8 client-owned horses, with cardioversion achieved in 7. No adverse responses to appropriately delivered shocks were observed. No antiarrhythmic medications were administered to any horse at any stage. Catheter design and placement technique evolved throughout the study, with combined ultrasonography and pressure guidance proving most effective in achieving appropriate electrode placement. Results suggest TVEC, as applied in the present study, is a safe, effective, and realistic therapeutic option for equine AF.

Transient complete atrioventricular block following transvenous electrical cardioversion of atrial fibrillation in a horse

Transvenous electrical cardioversion was attempted in a horse with drug refractory atrial fibrillation. A temporary pacing catheter and two defibrillation catheters were inserted transvenously into the right ventricular apex, the right atrium and the pulmonary artery, respectively. Under general anaesthesia 100, 200, 300 and 360 J monophasic shocks were delivered between both defibrillation catheters but sinus rhythm could not be restored. Immediately after the 200, 300 and 360 J shock, transient third-degree atrioventricular block occurred for a period of, respectively, 15, 40 and 55 s. These periods of profound bradycardia were corrected by temporary right ventricular pacing until spontaneous conduction resumed. It is concluded that temporary right ventricular pacing should be available during electrical cardioversion of atrial fibrillation in horses.

Transvenous Electrical Cardioversion in Equine Atrial Fibrillation: Technique and Successful Treatment of 3 Horses

Journal of Veterinary Internal MedicineVolume 17, Issue 5 p. 715-718 Open Access Transvenous Electrical Cardioversion in Equine Atrial Fibrillation: Technique and Successful Treatment of 3 Horses M. Kimberly J. McGurrin, M. Kimberly J. McGurrin Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorPeter W. Physick-Sheard, Corresponding Author Peter W. Physick-Sheard Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada. Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada; e-mail: pphysick@uoguelph.ca.Search for more papers by this authorDaniel G. Kenney, Daniel G. Kenney Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorCarolyn Kerr, Carolyn Kerr Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorW.J. Brad Hanna, W.J. Brad Hanna Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorFrancisco Teixeira Neto, Francisco Teixeira Neto Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorJ. Scott Weese, J. Scott Weese Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this author M. Kimberly J. McGurrin, M. Kimberly J. McGurrin Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorPeter W. Physick-Sheard, Corresponding Author Peter W. Physick-Sheard Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada. Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada; e-mail: pphysick@uoguelph.ca.Search for more papers by this authorDaniel G. Kenney, Daniel G. Kenney Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorCarolyn Kerr, Carolyn Kerr Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorW.J. Brad Hanna, W.J. Brad Hanna Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorFrancisco Teixeira Neto, Francisco Teixeira Neto Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this authorJ. Scott Weese, J. Scott Weese Department of Clinical Studies, Ontario Veterinary College, University ofGuelph, Guelph, ON, Canada.Search for more papers by this author First published: 28 June 2008 https://doi.org/10.1111/j.1939-1676.2003.tb02506.xCitations: 21AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume17, Issue5September 2003Pages 715-718 ReferencesRelatedInformation

Transvenous Electrical Cardioversion in Equine Atrial Fibrillation: Technique and Successful Treatment of 3 Horses

Transvenous Electrical Cardioversion in Equine Atrial Fibrillation: Technique and Successful Treatment of 3 Horses