Mahaim

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.

OBJECTIVE: To present the authors' experience of Mahaim-type accessory pathways (MAPs), focusing on anatomic localizations. METHODS: Data from consecutive patients who underwent electrophysiological study (EPS) for MAP ablation in two tertiary centres, between January 1998 and June 2020, were retrospectively analysed. RESULTS: Of the 55 included patients, 27 (49.1%) were male, and the overall mean age was 29.5 ± 11.6 years (range, 12-66 years)...

AIMS: Seeking to account for accessory atrioventricular conduction potentially leading to ventricular pre-excitation, Mahaim in the mid-20th century had described pathways between the atrioventricular conduction axis and the muscular ventricular septum. We aimed to look for such 'paraspecific' connections in adult human hearts. METHODS AND RESULTS: We serially sectioned 21 hearts, covering the triangle of Koch and the aortic root, and assessing the atrioventricular node, the penetration of the conduction axis, and the bundle branches in our search for fasciculo-ventricular connections...

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No abstract text is available yet for this article.

A retrospective study was conducted on pathologically diagnosed arrhythmogenic cardiomyopathy (ACM) from consecutive cases over the past 34 years ( n = 1109). The anatomo-pathological analyses were performed on 23 hearts diagnosed as ACM (2.07%) from a series of 1109 suspected cases, while histopathological data of cardiac conduction system (CCS) were available for 15 out of 23 cases. The CCS was removed in two blocks, containing the following structures: Sino-atrial node (SAN), atrio-ventricular junction (AVJ) including the atrio-ventricular node (AVN), the His bundle (HB), the bifurcation (BIF), the left bundle branch (LBB) and the right bundle branch (RBB)...

Atriofacicular pathways of Mahaim type are typically decrementally conducting accessory pathways without retrograde conduction properties, located on the right ventricular free wall at the tricuspid annulus. We report a patient with an atriofascicular pathway with minimal anterograde decremental conduction. Both long and short V-H antidromic atriofascicular reentrant tachycardias were induced and mechanism confirmed with electrophysiologic testing. Additionally, orthodromic atriofascicular reentrant tachycardia with narrow and right bundle branch block morphologies were inducible...

There is minimal data regarding antegrade-only accessory pathways in young patients. Given evolving recommendations and treatments, retrospective analysis of the clinical and electrophysiologic properties of antegrade-only pathways in patients <21 years old was performed, with subsequent comparison of electrophysiology properties to age-matched controls with bidirectional pathways. Of 522 consecutive young patients with ventricular pre-excitation referred for electrophysiology study, 33 (6.3%) had antegrade-only accessory pathways...

Anatomical concepts regarding the conduction system of the heart have been a matter of debate since pioneering work done at the beginning of the 20th century. Robert H. Anderson was actively involved in this field for half a century. We aimed to investigate how his own concepts evolved over time. We have assessed anatomical concepts relating to the cardiac conduction system appearing since the key contributions made in the initial decade of the 20th century, analyzing them from the perspective of Robert H. Anderson, particularly focusing on the anatomical aspects of structures such as accessory atrioventricular pathways, including the so-called Mahaim-type fibers, connections between the atrioventricular node and the atrial myocardium, and so-called "specialized" internodal atrial tracts...

AIMS: Mahaim-type accessory pathways (MAPs) are generally right-sided due to the embryological differentiation, but left-sided localization is also possible. This study aims to compare the clinical and electrophysiological characteristics of right- and left-sided MAPs. METHODS: Of 251 patients diagnosed with AP by electrophysiological study between November 2015 and February 2020, 12 patients with MAP were included (right sided n = 8, left sided n = 4)...

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...

Ventricular preexcitation is a depolarization of the ventricles that occurs before the conventional sequence, and the electrocardiogram is the specific test for diagnosis. A Kent bundle is the paradigm of ventricular preexcitation, and it is associated with short PR, wide QRS and delta wave. This finding is not always very evident, as it can have different degrees of pre-eccitazione; therefore great diagnostic care must be taken in this field. If not properly identified, the pattern of ventricular preexcitation may lead to an incorrect diagnosis...

Accessory pathways that bypass all or part of the normal atrioventricular conduction system traverse the atrioventricular junction. The atrioventricular junction comprises of a limited septal component and much more extensive right and left parietal components. Its composition forms a plane of insulation between atrial and ventricular myocardium, preventing direct continuity between them. Typical accessory atrioventricular pathways located anywhere along the atrioventricular junction are muscle bundles or may involve muscle around the walls of coronary sinus aneurysms or coronary veins...

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.

A 40-year-old man presented to our emergency department 2 hours after onset of shortness of breath, palpitations, and presyncope secondary to an adenosine-responsive wide complex tachycardia. Electrophysiology study was diagnostic for antidromic atrioventricular (AV) reentrant tachycardia utilizing a muscular connection from the anterior interventricular vein to the left ventricle with Mahaim-like properties, successfully treated with ablation in the distal coronary sinus (CS) system. This case highlights accessory pathways (a) with unique features (i...

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...

The prevalence of ventricular pre-excitation is 0.07-0.2% in the pediatric population. Kent bundle is the most common atrioventricular accessory pathway and Mahaim fiber is relatively rare. Approximately, 30-60% of children with ventricular pre-excitation have onset of atrioventricular reentrant tachycardia. Persistent atrioventricular reentrant tachycardia can lead to tachycardiomyopathy. The anterograde conduction of right accessory pathway might lead to ventricular systolic dyssynchrony which might result in cardiac dysfunction even in patients with no tachycardia onset...

Recognition of the presence, location, and properties of unusual accessory pathways for atrioventricular conduction is an exciting, frequently difficult, challenge for the clinical cardiac arrhythmologist. In this second part of our series of reviews relative to this topic, we discuss the steps required to achieve the correct diagnosis and appropriate management in patients with the so-called "Mahaim" variants of pre-excitation. We indicate that, nowadays, it is recognized that these abnormal rhythms are manifest because of the presence of atriofascicular pathways...

No abstract text is available yet for this article.

No abstract text is available yet for this article.