Atrioventricular Bypass Tract Research Articles

Electrophysiologic approach to diagnosis and ablation of patients with permanent junctional reciprocating tachycardia associated with complex anatomy and/or physiology.

Permanent junctional reciprocating tachycardia (PJRT) is a rare supraventricular tachycardia (SVT), typically involving a single decremental posteroseptal accessory pathway (AP). Four patients with long RP SVT underwent electrophysiology (EP) study and ablation. The cases were reviewed. Case 1 recurred despite 3 prior ablations at the site of earliest retrograde atrial activation during orthodromic reciprocating tachycardia (ORT). Mapping during a repeat EP study demonstrated a prepotential in the coronary sinus (CS). Ablation over the earliest atrial activation in the CS resulted in dissociation of the potential from the atrium during sinus rhythm. The potential was traced back to the CS os and ablated. Case 2 underwent successful ablation at 6 o'clock on the mitral annulus (MA). ORT recurred and successful ablation was performed at 1 o'clock on the MA. Case 3 had tachycardia with variation in both V-A and A-H intervals which precluded the use of usual maneuvers so we used simultaneous atrial and ventricular pacing and introduced a premature atrial contraction with a closely coupled premature ventricular contraction. Case 4 had had two prior atrial fibrillation ablations with continued SVT over a decremental atrioventricular bypass tract that was successfully ablated at 5 o'clock on the tricuspid annulus. A second SVT consistent with a concealed nodoventricular pathway was successfully ablated at the right inferior extension of the AV nodal slow pathway. We describe challenging cases of PJRT by virtue of complex anatomy, diagnostic features, and multiple arrhythmia mechanisms.

Impact of fasciculoventricular bypass tracts on the diagnosis and treatment of concomitant arrhythmias and cardiac diseases

BackgroundFasciculoventricular (FV) bypass tracts (BTs) are the rarest form of ventricular preexcitation. Although they are not involved in clinically significant reentrant tachycardia, they may cause diagnostic and therapeutic confusion if not properly understood. This study aimed to assess the impact of FV BTs on the diagnosis and treatment of concomitant arrhythmias and cardiac diseases. MethodsTwenty-two patients with FV BTs who underwent electrophysiologic (EP) study were evaluated. The prevalence of concomitant arrhythmias and cardiac diseases in FV BTs was evaluated. The mechanisms of concomitant arrhythmias were determined by EP study and cardiac diseases were diagnosed by echocardiography. ResultsOne patient had FV BT with complete infra-Hisian atrioventricular (AV) block that mimicked a slow ventricular escape rhythm. Two patients had FV BT with atrial fibrillation or atrial flutter, which was misinterpreted as AV BT requiring emergency DC cardioversion. Eight patients had accompanying AV BTs. In 2 patients with AV BTs, unnecessary RF application was delivered after successful ablation of AV BT because conduction through a FV BT was mistaken for conduction through a residual AV BT. Five patients had no concomitant arrhythmia; however, two of them had hypertrophic cardiomyopathy with symptoms requiring beta-blocker. Patients had not been prescribed beta-blockers to avoid a proarrhythmic response before the EP study because the FV BTs mimicked AV BTs. ConclusionFV BTs were frequently accompanied by AV BTs or other arrhythmias and cardiac diseases. They may cause misdiagnosis and inappropriate therapy and even unnecessary RF delivery when misinterpreted as AV BTs.

Diagnostic Perturbations.

Diagnostic Perturbations.

Members of the emergency medical team may have difficulty diagnosing rapid atrial fibrillation in Wolff-Parkinson-White syndrome.

Atrial fibrillation (AF) in patients with Wolff-Parkinson-White (WPW) syndrome is potentially life-threatening as it may deteriorate into ventricular fibrillation. The aim of this study was to assess whether the emergency medical team members are able to diagnose AF with a rapid ventricular response due to the presence of atrioventricular bypass tract in WPW syndrome. The study group consisted of 316 participants attending a national congress of emergency medicine. A total of 196 questionnaires regarding recognition and management of cardiac arrhythmias were distributed. The assessed part presented a clinical scenario with a young hemodynamically stable man who had a 12-lead electrocardiogram performed in the past with signs of pre-excitation, and who presented to the emergency team with an irregular broad QRS-complex tachycardia. A total of 71 questionnaires were filled in. Only one responder recognized AF due to WPW syndrome, while 5 other responders recognized WPW syndrome and paroxysmal supraventricular tachycardia or broad QRS-complex tachycardia. About 20% of participants did not select any diagnosis, pointing out a method of treatment only. The most common diagnosis found in the survey was ventricular tachycardia/broad QRS-complex tachycardia marked by approximately a half of the participants. Nearly 18% of participants recognized WPW syndrome, whereas AF was recognized by less than 10% of participants. Members of emergency medical teams have limited skills for recognizing WPW syndrome with rapid AF, and ventricular tachycardia is the most frequent incorrect diagnosis.

Bypass tracts revisited.

The study of atrioventricular bypass tracts remains an educational cornerstone for students of electrophysiology seeking to understand the principles of reentry, mapping, tachycardia mechanism diagnosis in the electrophysiology laboratory, and ablation. Surgical and subsequently catheter ablation procedures to eliminate these tracts derived from an understanding of their anatomic location, typically bridging the atrioventricular annulus allowing conduction from atrium to ventricle to bypass the normal atrioventricular node. With this appreciation of anatomy and physiology, pacing maneuvers can be applied and interpreted to clarify the presence and electrophysiological properties of atrioventricular bypass tracts in the electrophysiology laboratory. Article see p 1262 In this segment of Teaching Points in Electrophysiology, Patel and colleagues1 present and carefully examine a different type of bypass tract, one connecting the right atrium to a pulmonary vein (PV) bypassing the left atrial myocardium. The underlying principle for PV isolation derives from the construct that the PV myocardium is solely activated via conduction from the left atrial myocardium across the PV ostium.2,3 The presence of an intercaval bundle creating a tract that electrically connects the posterior right atrium and the anterior aspect of the right superior PV makes isolation of this vein with left atrial ablation alone impossible. Similar tracts may also bypass the left atrium and connect a left PV to the coronary sinus (CS) musculature, to the left atrial appendage (LAA), or to an adjacent left PV. In the latter case, ostial encircling ablation lines will fail to isolate the vein. In the former 2 cases, even encircling antral ablation lines around the left PVs may fail to isolate these structures. In some patients, the remnant of the left superior vena cava—the ligament and vein of Marshall (VOM)—serves as the tract connecting the CS myocardium to a PV.2 The presence of these …

Catheter Ablation of an Unusual Decremental Accessory Pathway in the Left Coronary Cusp of the Aortic Valve Mimicking Outflow Tract Ventricular Tachycardia

The anatomic location of atrioventricular (AV) bypass tracts (or accessory pathways) is variable, but these generally traverse the tricuspid or mitral annulus and insert into the atrium and ventricle near the AV ring. There is only 1 case report of an accessory pathway ablated in the left coronary cusp (LCC),1 and this pathway had bidirectional conduction, was not decremental, and was associated with an orthodromic tachycardia. We report here the first case of an antegrade slowly conducting, decremental, accessory pathway that was also successfully ablated in the aortic LCC. This pathway generated antidromic tachycardia having a QRS morphology mimicking those seen in outflow tract ventricular tachycardia. A 42-year-old woman was evaluated for palpitations and presyncope for 2 years. These were commonly associated with shortness of breath and chest heaviness that would resolve spontaneously. Her baseline ECG was normal without ventricular preexcitation. Echocardiogram, coronary angiogram, and thyroid function were also unremarkable. On her third presentation to a hospital, a broad complex tachycardia was captured (representative 12-lead ECG shown in Figure 1). The cycle length was 480 ms, the QRS duration was 150 ms, and a left bundle branch morphology with a right inferior axis was noted. She was referred for ablation of suspected ventricular outflow tract tachycardia. Consent was obtained for mapping and ablation of this tachycardia. During placement of catheters, a spontaneous initiation of tachycardia occurred, which was noted to have 1:1 AV association. A quadripolar catheter was placed at the right ventricular apex and His bundle, with a decapolar catheter in the coronary sinus. During ventricular pacing, retrograde conduction occurred with a long ventriculoatrial interval. Tachycardia was readily initiated with ventricular premature beats showing retrograde decremental conduction (Figure 2). An antegradely conducting accessory pathway was noted during atrial pacing maneuvers. During delivery of premature atrial stimulations, shortening of …

Rare Forms of Preexcitation

A 16-year-old boy was brought to the hospital when he complained of chest pain while at a basketball game. In the emergency room, he was noted to have a wide complex tachycardia. The ECG at presentation is shown in Figure 1. He was cardioverted after administration of 150 mg of intravenous amiodarone. His ECG after cardioversion is shown in Figure 2. His physical examination and developmental evaluation were significant for obesity, synophrys, mild fifth digit clinodactyly, and subnormal intelligence. Cardiac magnetic resonance imaging with contrast showed massive left ventricular hypertrophy (LVH), with preserved ejection fraction, and several areas of delayed hyperenhancement in the subendocardium. Cardiac catheterization showed no obstructive coronary artery disease or anomalous coronary arteries. What are the diagnostic considerations for this constellation of findings of massive LVH, subendocardial necrosis, and abnormal ECGs? Figure 1. Wide complex tachycardia at presentation. Figure 2. Sinus rhythm ECG showing ventricular preexcitation and normal axis (see text for further details). The ECG in Figure 1 displays a wide complex tachycardia, with a right-bundle branch block morphology with a QRS complex duration >120 ms. A wide complex tachycardia with a right-bundle branch block morphology could be secondary to ventricular tachycardia originating from the left ventricle or a preexcited tachycardia in the presence of a left-sided bypass tract. However, the QS complex in lead V6 rules out a left-sided atrioventricular bypass tract, because such bypass tracts do not have the left ventricle apex as their ventricular insertion site, which is necessary to produce a QS complex in V6. A left-sided nodofascicular bypass tract with insertion in the distal His-Purkinje system can produce QS complexes in lead V6, but these are extraordinarily rare and occur more frequently on the right side. Initial R wave in lead aVR,1 a QS complex in lead …

Catheter ablation of an atrioventricular bypass tract connecting a funnel-shaped bilobular left atrial appendage with the ventricular free wall

A female patient with Wolff-Parkinson-White syndrome and frequent episodes of atrioventricular reentrant tachycardia was referred for electrophysiologic evaluation and interventional treatment. Twelve-lead surface ECG showed preexcitation with a negative delta wave in leads I and aVL and positive delta waves in the inferior leads and leads V1–V6, indicating a left posterior accessory pathway (AP) localization. After confirmation of a left posterior AP localization by an eccentric activation in the coronary sinus (CS) during both sinus rhythm and retrograde stimulation, the left atrium (LA) was accessed via a transseptal puncture for an anterograde approach.

Accessory Atrioventricular Pathways

By definition, accessory atrioventricular pathways are aberrant muscle bundles that connect the atrium to a ventricle outside of the regular atrioventricular conduction system. Clinically, they may manifest as substrates for ventricular preexcitation. The first accessory pathway in a patient who suffered from Wolff-Parkinson-White syndrome was described in 1943 by Wood, Wolferth, and Geckler.1 Shortly after, Ohnell created a reconstruction of an accessory pathway that very elegantly showed the close proximity of the pathway to the fibrous attachment of the mitral valve and its relationship with the sulcus coronarius (Figure, A).2 Subsequent histological studies have demonstrated unequivocally that these pathways are the anatomic substrates for the classical Wolff-Parkinson-White variety of preexcitation. Figure. A, Ohnell’s depiction of an accessory bundle in the left atrioventricular groove.2 Reprinted with permission from Blackwell Publishing. B, Histological section stained with Masson’s trichrome (fibrous tissue in green and myocardium in red) to show an accessory left-sided pathway (arrow) skirting the mitral annulus. C, Histological section showing a broad right-sided accessory pathway (arrow) that is formed by a myocardial pouch extending from the right atrial appendage to the ventricle and ultimately traced to a small right ventricular vein. This pathway is some distance from the fibrous annulus of the tricuspid valve. *Valvar annulus. Article p 1508 Accessory atrioventricular pathways are found most often in the parietal atrioventricular junctional areas, including the paraseptal areas. They breach the insulation provided by the fibrofatty tissues of the atrioventricular groove (sulcus tissue) and the hingelines (fibrous annulus) of the valves. They are rarely found in the area of fibrous continuity between the aortic and mitral valves because in this area, there is usually a wide gap between the atrial myocardium and ventricular myocardium to accommodate the aortic outflow tract. On the left parietal side, the accessory pathways tend …

Supraventricular tachycardia in children.

Several different mechanisms are responsible for paroxysmal supraventricular tachycardia in children. Different forms of tachycardia occur at different age. Atrio-ventricular reentry tachycardia results from the presence of congenital atrio-ventricular bypass tracts and is frequently encountered at all ages. Infants may present with ectopic atrial tachycardia or atrial flutter. Atrio-ventricular node reentry tachycardia becomes more frequent in adolescence. Atrial scarring resulting from open heart surgery predisposes to complex intra-atrial reentry. Certain forms of congenital and acquired heart disease are associated with specific types of arrhythmia. Many children with paroxysmal supraventricular tachycardia do not require any therapy. The decision to proceed with treatment should be based on the frequency and severity of symptoms and on the effect of arrhythmia on the quality of life. Infants require medical treatment because of the difficulty to recognize symptoms of tachycardia and a risk of heart failure. Patients with Wolff-Parkinson-White syndrome as well as those with significant heart disease are at risk of sudden death. Syncope in children with paroxysmal tachycardia may indicate a severe fall in cardiac output from extremely rapid heart rate. Patients with potentially life-threatening arrhythmia should not participate in competitive physical activities. Treatment options have undergone significant evolution over the past decade. Indications for the use of specific antiarrhythmic medications have been refined. Contemporary catheter ablation procedures employ different forms of energy allowing for safe and effective procedures. Catheter ablation is the treatment of choice for symptomatic paroxysmal tachycardia in school children and in some infants who failed medical treatment. Surgery is the preferred treatment in few selected cases. The goal of this review is to present the state of the art approach to the diagnosis and management of paroxysmal supraventricular tachycardia in infants, children and adolescents.

Electrocardiographic manifestations: wide complex tachycardia due to accessory pathway

Tachycardia with a wide QRS complex is usually due to ventricular tachycardia (VT), supraventricular tachycardia (SVT) with aberrant intraventricular conduction, or an accessory pathway-mediated dysrhythmia. The most common type of accessory pathway causing a wide complex tachycardia is the atrioventricular bypass tract. Distinguishing the accessory pathway-mediated tachycardia from VT or SVT with aberrancy is often difficult, but has important clinical consequences. This article will review the diagnosis of wide complex tachycardia due to an accessory pathway and its related management in the emergent setting.

Radiofrequency ablation of multiple accessory pathways.

The aim of the study was to review the clinical and electrophysiological characteristics and results of radiofrequency catheter ablation in patients with multiple accessory pathways to compare them with those of patients with single accessory pathways. Electrophysiological study and radiofrequency catheter ablation were performed in 1010 consecutive cases with Wolff Parkinson White Syndrome. Presence of multiple accessory pathways was documented in 31 patients (3.1%); 30 had two, and 1 had three accessory pathways. Of the 63 accessory pathways, 42 were manifest and 21 concealed. Nine patients had Ebstein's anomaly associated with atrioventricular bypass tracts. The most common combination was right posteroseptal with right free wall bypass tracts (15 patients with 30 accessory pathways). Fifty-one of the sixty-three accessory pathways (81%) were ablated successfully without complications. The duration of the procedure was 100 +/- 58 min and the fluoroscopic time 40 +/- 17 min. A follow up of 5 +/- 3 years after ablation, demonstrated recurrences of six accessory pathways (9.5%). In conclusion, patients with multiple accessory pathways can be treated by radiofrequency ablation in only one session with a high success rate although slightly less than that in patients with a single accessory pathway (81% vs 93%, P<0.01).

New preexcitation following cardiac transplant

Preexcitation developed post-operatively in a cardiac transplant recipient whose donor electrocardiogram was normal. An electrophysiology study revealed evidence of a mid-septal atrioventricular (AV) bypass tract. The patient is clinically well fourteen months after transplant and has intermittent preexcitation.

Is there a future for antiarrhythmic drug therapy?

Drug therapy has traditionally been the mainstay of treatment for both ventricular and supraventricular arrhythmias. However, increasing knowledge about the potentially significant adverse effects of these medications, together with the emergence of new, nonpharmacological approaches to the treatment of arrhythmias, has led some to question the future of antiarrhythmic drug therapy. Antiarrhythmic drugs are quite effective in terminating a variety of arrhythmias, including atrioventricular (AV) node re-entrant and AV tachycardias (particularly calcium antagonists and adenosine), atrial flutter (class III agents) and atrial fibrillation (class IA and IC drugs. The chronic use of antiarrhythmic drugs has been increasingly limited by a fear of adverse effects (especially proarrhythmia) and the availability of highly effective nonpharmacological alternatives (particularly ablation for re-entrant tachycardias involving the AV node and bypass tracts and cardiovertor/defibrillators for malignant ventricular arrhythmias. Atrial fibrillation (AF) continues to be a therapeutic challenge for which there is no safe and curative nonpharmacological therapy. Antiarrhythmic drugs of classes IA, IC and III show efficacy in preventing recurrence of AF but there are concerns about possible pro-arrhythmic complications. In the future, antiarrhythmic agents will continue to be used acutely to terminate a broad range of sustained arrhythmias. Chronic use is likely to depend on the development of safer and/or more effective compounds, as well as on improved ways of predicting which patients are likely to develop pro-arrhythmic reactions. The development of molecular electrophysiology will allow for the identification of agents with selected ion channel blocking profiles which may prove efficacious with a lower risk of complications. Finally, an improved understanding of arrhythmia substrates may permit the identification of therapy that prevents arrhythmias by acting on the underlying substrate, rather than simply trying to modify the electrical end product.

Iatrogenic atrioventricular bypass tract following a Fontan operation for tricuspid atresia.

A 16 year old female with tricuspid atresia had undergone a Fontan operation at four years of age. Two years later she first presented with a narrow complex tachycardia which...

Feasibility of radiofrequency powered, thermal balloon ablation of atrioventricular bypass tracts via the coronary sinus: in vivo canine studies.

Radiofrequency catheter ablation of left-sided accessory pathways is technically demanding and usually requires left heart catheterization. The feasibility of creating lesions from within the coronary sinus of sufficient size to ablate accessory pathways in humans using a thermal balloon catheter was studied in 20 dogs. In group 1 (n = 14), 17 thermal inflations were performed in 12 dogs at either 70 degrees, 80 degrees, or 90 degrees C each for 30 or 60 seconds (in 2 dogs two non-thermal control inflations were performed). Animals were sacrificed 6.3 +/- 1.6 days later. In group 2 (n = 6), seven thermal inflations were performed at 90 degrees C each for 180, 300, or 360 seconds. Group 2 animals received antiplatelet and anticoagulant therapy for 1 week and were sacrificed at 13 +/- 10.7 days. In both groups, hemodynamic, angiographic, and electrocardiographic studies were performed at baseline, 1 hour after inflation, and prior to sacrifice. All dogs remained clinically stable throughout the procedure and no complications were attributed to the effect of thermal inflation. Thermal lesions measured 14.4 +/- 4.4 mm in length and extended from the coronary sinus intima to a mean depth of 2.9 +/- 1.2 mm (range 1.4-6.5 mm). Group 2 lesions were significantly deeper than group 1 lesions (P = 0.03). Of the 24 thermal lesions created, atrial necrosis was present in 23 and ventricular necrosis in 11. In all lesions there was some degree of either atrial necrosis, ventricular necrosis, or both. A variable degree of coronary sinus thrombus was present in 18 dogs without clinical sequelae. It is concluded that radiofrequency balloon heating via the coronary sinus can create thermal lesions in the atrioventricular sulcus of dogs that may be of sufficient size to ablate accessory left-sided pathways in humans.

SURGICAL TREATMENT FOR ATRIAL FIBRILLATION.

Surgical procedures have been successfully used to treat ventricular arrhythmias and tachycardias involving atrioventricular bypass tracts, but not the

Modification of human atrioventricular nodal function by selective atrioventricular nodal artery catheterization.

The hypothesis that human atrioventricular (AV) nodal function can be modulated selectively with a new technique of AV nodal artery catheterization was tested in eight subjects referred for diagnostic cardiac catheterization or electrophysiological studies. Three patients had no history of arrhythmias. Three patients had supraventricular tachycardia (SVT) due to reentry confined to the AV node (AVNRT). One patient had SVT due to reentry over a concealed AV bypass tract (AVRT-CBT), and one patient had nonsustained ventricular tachycardia. In each subject, sinus cycle length, AH interval, HV interval, AV nodal effective refractory period (AVN-ERP), and Wenckebach paced cycle length were measured in a control state. A flexible infusion catheter was then positioned selectively in the AV nodal artery of each subject. Through this catheter, a constant infusion of 0.1 mg/min procainamide at a flow rate of 0.125 ml/min (n = 1) or 50 micrograms/min acetylcholine at a flow rate of 0.25 ml/min (n = 4) was administered. Electrophysiological parameters were determined again during selective AV nodal artery drug infusion and during infusion of saline at identical rates. Two subjects developed transient AV nodal block during selective AV nodal catheterization alone and did not receive an infusion of drug or saline. A stable position of the AV nodal artery catheter could not be achieved in one other subject, who also received no drug or saline. In the other five subjects, drug infusion caused an increase in AVN-ERP from a control value of 312 +/- 52 msec to a value of 543 +/- 228 msec (p less than 0.05) and an increase in Wenckebach paced cycle length from a control value of 360 +/- 47 msec to a value of 572 +/- 217 msec (p less than 0.05). These parameters were unchanged from control during selective saline infusion. In two patients with AVNRT, drug infusion abolished SVT by causing complete blockade of ventriculoatrial conduction as well as lengthening of anterograde AVN-ERP. In the patient with AVRT-CBT, drug infusion abolished SVT by preventing repetitive anterograde AV conduction. Saline had no effect on SVT inducibility. Selective AV nodal artery catheterization enables AV nodal function to be modulated exclusively. Delivery of ablative agents to the AV node by this technique may be useful in patients with refractory SVT.

Wolff‐Parkinson‐White Syndrome Associated with a Coronary Sinus Diverticulum: Ablative Surgical Approach

This report concerns a patient with drug refractory supraventricular tachycardia due to the Wolff-Parkinson-White syndrome in association with a coronary sinus diverticulum. Division of the anomalous bypass tract was initially performed by an endocardial approach together with circumferential dissection of the neck of the diverticulum. This procedure failed to ablate the bypass tract that was only successfully divided when the superficial wall of the diverticulum was excised. This case illustrates the close association that exists between an anomalous atrioventricular bypass tract and a coronary sinus diverticulum, and the importance of dividing the superficial wall of the diverticulum as an integral part of the ablative procedure.

Catheter ablation of atrioventricular bypass tracts. Still an investigational procedure.

Une comparaison de la technique d'ablation par sonde au procede chirurgical standard actuel revele que la chirurgie est actuellement nettement plus fiable que la technique par sonde