A case of antidromic atrioventricular reciprocating tachycardia via the atriofascicular pathway with suspected minor manifest fusion during ventricular pacing.

In this case with antidromic atrioventricular reciprocating tachycardia via the atriofascicular pathway, entrainment from the right ventricular apex showed minor constant fusion. This may indicate that an atriofascicular pathway with distal arborization can connect to the branch of the right bundle and partly to the working myocardium.

Anatomy for ablation of atrioventricular nodal reentry tachycardia and accessory pathways.

The atrioventricular (AV) valve plane and the central septum are of particular importance for electrophysiological diagnosis and interventional therapy of supraventricular tachycardias because accessory electrical connections of various types may be present in addition to the specific conduction system. Although modern 3D electroanatomic reconstruction systems including high-density mapping can be of great assistance, detailed knowledge of the anatomic structures involved, their complex three-dimensional arrangement, and their electrical properties in conjunction with electrophysiological features of supraventricular arrhythmias is essential for safe and efficient electrophysiological treatment. The aim of this article is to present current anatomical, topographical, and electrophysiological findings against the background of historical, seminal, and still indispensable literature.

Left free wall-sided Mahaim type fiber and A-V nodal reentry tachycardia: Unusual but not impossible combination.

A 52-year-old patient with previous catheter ablation of A-V nodal reentrant tachycardia (AVNRT) had a redo procedure for reported recurrence. During the study, AVNRT was not inducible, but a previously unrecognized left-sided Mahaim-type accessory pathway was diagnosed and ablated successfully.

Rare narrow QRS tachycardia with atrioventricular dissociation: A case report.

BACKGROUND: Most Mahaim fibers are right free-wall atriofascicular accessory pathways with only antegrade conduction. Concealed Mahaim fiber is not very rare; however, concealed nodoventricular fiber is a very rare kind of retrograde accessory pathway in supraventricular tachycardia with atrioventricular (AV) dissociation. Only a few cases about successful ablation of the nodoventricular accessory pathway have been reported. We describe the case of a 32-year-old woman who underwent an electrophysiology study and radiofrequency (RF) ablation of a rare narrow QRS tachycardia with AV dissociation. CASE SUMMARY: A 32-year-old woman with a history of paroxysmal palpitation was admitted to our hospital for RF ablation. Electrocardiography revealed a narrow QRS complex tachycardia with the same morphology in sinus rhythm. Echocardiography showed no structural heart disease. A right-sided concealed AV accessory pathway and a right-sided concealed nodoventricular accessory pathway were involved in the orthodromic atrioventricular reciprocating tachycardia. His bundle-ventricular interval during tachycardia was the same as that in sinus rhythm. The tachycardia could be initiated and entrained by ventricular pacing. Premature right ventricular stimulus introduced during the His-bundle refractory period when tachycardia occurred was able to advance the next atrial potential. The earliest atrial activation was mapped near the proximal slow AV nodal pathway. RF ablation of both accessary pathways was successfully performed under the guidance of a three-dimensional mapping system by recording the earliest retrograde atrial potential, and tachycardia could no longer be induced. CONCLUSION: Narrow QRS tachycardia with AV dissociation is inducible by concealed nodoventricular fiber and ablated by recording the earliest retrograde atrial potential.

Mahaim pathway potential revealed by high-resolution three-dimensional mapping.

Mapping and ablation of atriofascicular fibers can be highly challenging due to the complex and dynamic anatomy of the tricuspid valve annulus. This case highlights the utility of a multi-electrode catheter three-dimensional mapping approach to localize the Mahaim pathway along the tricuspid annulus in order to guide catheter ablation.

Mahaim fiber connecting the right atrium to the left ventricle: a case report.

In the majority of cases presenting with the Mahaim fiber (MF), the MF connects the lateral right atrium (RA) to the right bundle branch or the right ventricle. We present the case of a 33-year-old man with antidromic atrioventricular reentrant tachycardia using MF connected to the septal RA and left ventricle (LV). Although the Mahaim potential was recorded at the septal RA, ablation at this site could not eliminate the MF and had a potential risk of injury to the atrioventricular node. Additional application at the posterior septal LV achieved successful MF ablation.

Perioperative management of patients with pre-excitation syndromes.

Patients with pre-excitation abnormalities are at a high risk for life-threatening perioperative arrhythmias. In Wolff-Parkinson-White syndrome, the anaesthetics used for invasive diagnostic testing/ablation, should not affect cardiac electrophysiology; propofol, sevoflurane, fentanyl, sufentanil, alfentanil are suitable. In non-ablative surgery, propofol, sevoflurane, isoflurane, fentanyl, alfentanil, sufentanil have been used safely. Among neuromuscular blockers, cis-atracurium, rocuronium and vecuronium are good choices. Ketamine, pancuronium and pethidine should be avoided because of their sympathomimetic actions. Anticholinergic/ anticholinesterase combinations for neuromuscular block reversal should preferably be omitted, while sugammadex seems more attractive. In regional anaesthesia, addition of epinephrine and high sympathetic blocks should be avoided. Hypotension should be treated with pure alpha-adrenergic agonists. Other pre-excitation abnormalities associated with different accessory pathways are the Mahaim Fiber and Lown-Ganong-Levine syndrome. Sympathetic activation should be avoided. Total intravenous anaesthesia with propofol probably represents the safest option. A careful anaesthetic plan and close cooperation with cardiologists are mandatory for successful management.

Mahaim fiber-mediated tachycardia. / Taquicardia mediada por via Mahaim.

We present the case of a previously healthy 42-year-old man who attended the emergency department due to a sudden onset of rapid and regular palpitations. The ECG showed 190 bpm, wide QRS with left bundle branch block tachycardia. He was started on amiodarone with progression to 230 bpm, wide QRS tachycardia with multiple morphologies, followed by spontaneous conversion to sinus rhythm, normal PR interval and rS pattern in LIII. The echocardiogram was negative for structural heart disease. The electrophysiological study demonstrated the presence of an accessory pathway with anterograde decremental conduction and no retrograde conduction. Both episodes of clinical tachycardia were induced. A diagnosis of Mahaim fiber-mediated antidromic atrioventricular reentrant tachycardia and pre-excited atrial fibrillation was made. Mapping was performed with detection of an M potential (His-like) at the lateral region of the tricuspid ring followed by radiofrequency ablation with immediate success criteria. Post-ablation there was a change to a qR pattern in LIII. At 12-months follow-up there was no recurrence of the tachycardia.

Persistent ventricular preexcitation despite right bundle branch block.

A 44-year-old man with a history of ventricular preexcitation and supraventricular tachycardia was evaluated. The baseline electrocardiogram exhibited ventricular preexcitation with a normal PR interval and a minimally negative delta wave in lead V1 and positive delta waves in the inferior leads. The administration of adenosine resulted in a progressive prolongation of the PR interval with a fixed preexcitation degree, suggesting the presence of antegrade conduction over the fasciculo-ventricular pathway. When complete right bundle branch block occurred, the degree of preexcitation never changed. These findings suggested that the fasciculo-ventricular pathway was likely to be connected to the left-sided His-Purkinje system.

Preexcitation Syndrome with a Mahaim-type Accessory Pathway

Wide QRS complex tachycardia with a left bundle branch block pattern can be caused by supraventricular tachycardia with aberrant conduction, preexcitation syndrome mediated through a right-sided accessory pathway, and/or ventricular tachycardia. The use of atrial pacing maneuvers can be beneficial for unmasking minimal preexcitation to differentiate between these conditions. Here, we report a case of successful radiofrequency catheter ablation of a Mahaim fiber in a patient with wide QRS complex tachycardia.

[Congenital heart defects in adulthood : Supraventricular tachycardia]. / Angeborene Herzfehler im Erwachsenenalter : Supraventrikuläre Tachykardien.

Supraventricular tachycardia (SVT) based on congenital substrates, such as accessory pathways or dual atrioventricular nodal properties, occur with an increased probability linked to specific congenital heart defects (CHDs). In the literature, the association of Ebstein's anomaly with accessory pathways and with Mahaim fibers is most prominent. Compared with patients with otherwise normal hearts, the clinical relevance of SVT is typically more severe and therefore antiarrhythmia treatment is a necessity in many cases. Diagnostics, pharmaceutical treatment, and interventional therapy of SVT in patients with CHD are often demanding owing to anatomical, hemodynamic, and electro-anatomical peculiarities. The use of antiarrhythmic medication is often limited because of intolerable side effects and a lack of reliability in suppressing arrhythmia relapses in the long term. Within the last 15-20 years catheter ablation has thus become established as the first-choice treatment for SVT, even in patients with CHD. However, rates of success, recurrence, and risks are still inferior to those observed in patients with a normally functioning heart owing to the co-existence of vascular and cardiac anomalies, surgically created alterations, an unusual electro-anatomy, and lower tolerance to hemodynamic changes. Successful treatment in patients with CHDs and SVT requires a deep understanding and knowledge of all the disciplines discussed above and should only be practiced in dedicated centers, as patient numbers are small and therefore experience is limited.

Is the 12-lead electrocardiogram during antidromic circus movement tachycardia helpful in predicting the ablation site in atriofascicular pathways?

AIMS: Unlike in the Wolff-Parkinson-White syndrome, there has been no systematic study on the role of the pre-excitation pattern in predicting the ablation site in patients with atriofascicular (AF) pathways. We assessed in a large cohort the value of the 12-lead electrocardiogram (ECG) during antidromic tachycardia (ADT) to predict the site of ablation. METHODS AND RESULTS: Forty-five patients were studied, 23 males (51%), mean age of 27 ± 12 years with 46 AF pathways and 48 ADT using the AF pathway for A-V conduction. Inclusion required induction of a sustained ADT and successful ablation. Ablation site was assessed during LAO 45° projection and clockwise classified as hours in posteroseptal, posterolateral, lateral, anterolateral, and anteroseptal tricuspid annulus as follows: 05:00-07:00, >07:00-08:00, >08:00-09:00, >09:00-11:00, and >11:00-13:00 o'clock. The QRS axis was assessed during ADT and classified as normal (>+15°), horizontal (+15° to -30°), and superior (<-30°). During ADT axis was superior (-57° ± 10°) in 15 (31%), horizontal (-11° ± 14°) in 22 (46%), and normal (+45° ± 16°) in 11 (23%) patients. The correct ablation site did not differ between the different groups of QRS axis. QRS width during ADT was narrower in patients with a normal when compared with a horizontal and leftward axis (127 ± 14 vs. 145 ± 12 ms, P < 0.0001), and the V-H interval was shorter (4 ± 3 ms vs. 19 ± 22 ms, P = 0.03). CONCLUSIONS: There was no correlation between the AF pathway ablation site and the QRS axis during ADT. The 12-lead ECG during maximal pre-excitation does not predict the proper site of tricuspid annulus ablation in patients with A-V conduction over an AF pathway.

Electrophysiological characteristics and catheter ablation left-sided accessory pathways of Mahaim fiber / 中国医师进修杂志

ObjectiveTo study electrophysiological characteristics and catheter ablation left-sided accessory pathways of Mahaim fiber.MethodsTwenty-eight patients underwent catheter ablation for Mabaim fiber and 3 patients was left-sided accessory pathways.All of them were male with 34,20,38 years old.The tachycardia history was1-5years. Electrophysiological characteristics,target sitesand electrocardiogram(ECG,12 leads) were recorded through catheter from coronary sinus(CS),high right atrium(HRA),His bundle and ablation.ResultsOne patient's ECG showed little preexcitation,the other two were normal. Atrial stimulation could be easily induced tachycardia.Their ECG showed wide QRS waves (right bundle branch block or similar right bundle branch block).The characteristics of accessory pathways were slow and anterograde decremental conduction as well as blocked by adenosine triphosphate injection.Ventricular-atrial conduction was via atrioventricular node with centripetal decreasing transmission during ventricular pacing.During tachycardia,the His bundle electrogram resulted in a V-H-A pattern,the retrograde A in His bundle was pioneer.The atriofascicular pathways of 2 patients were completely ablated respectively in left posterior lateral and before the free wall of mitral valve ring.The nodoventricular pathway of 1 patient was successfully ablated in left middle posterior lateral of mitral valve ring.ConclusionsThe left-sided accessory pathways of Mahaim fiber is an uncommon accessory pathway,which has specific electrophysiological characteristics.It is effective and safe to ablate accessory pathway with radiofrequency.

Mahaim fiber accelerated automaticity and clues to a mahaim fiber being morphologically an ectopic or a split AV node.

Mahaim Fiber tachycardia characteristically causes a wide QRS tachycardia with left bundle branch morphology and left axis deviation, especially in young patients, having no structural heart disease. Mahaim fiber automaticity further cements the proposition of Mahaim fiber, due to its Atrioventricular (AV) node like property, being called as an ectopic AV node.

Ablation techniques for mahaim fiber tachycardia.

Mahaim fiber exhibits atrio-ventricular node like properties and generally is localized at the lateral aspect of the tricuspid annulus. Of the varying methods for localization, ablation at the site of Mahaim potential is the most accepted and successful method. Radiofrequency ablation of Mahaim fiber has high success rates.