title: The clinical course and risk in patients with pseudo-Mahaim fibers.
abstract: BACKGROUND
  Pseudo-Mahaim (AP-M) fibers are a rare variant of atrioventricular (AV) accessory pathways. Atriofascicular and atrioventricular accessory connections are characterized by slow conduction and decremental properties. Dual physiological AV node pathways, slow and fast, are observed in a large number of patients with AP-M. Therefore, there is substrate for AV nodal reentrant tachycardia (AVNRT) in addition to antidromic AV reentrant tachycardia (AVRT) with left bundle branch block (LBBB)-like morphology. Other arrhythmia such as atrial fibrillation (AF) or atrial flutter (AFL) and ventricular fibrillation (VF) are also observed. We analysed the occurrence of arrhythmias in a group of patients with AP-M treated in our department.
  
  
  METHODS
  We evaluated 27 patients (12 women) aged 14-53 years (mean age 25.6 years) with AP-M. The clinical course in these patients, in particular with regard to the occurrence of arrhythmias, was analysed. Patients with dual AV node properties were compared to patients without such findings.
  
  
  RESULTS
  We found dual AV node properties in 18 patients (Group 1), while 9 patients had fast pathway only (Group 2). Twenty-six patients presented with AVRT, 2 patients with AVNRT, 3 patients with AF, 1 patient with AT, 2 patients with AFL, and 3 patients with VF. In 2 patients, AP-M were seen in an atypical area. In one patient, the pathway connected the right atrium with the left ventricle (septal region), and in the other patient it connected the left atrium with the left ventricle (left anterior region).
  
  
  CONCLUSIONS
  The majority of AP-M was right-sided. Two thirds of patients with AP-M had anatomical substrate for AVNRT (fast/slow pathway AV node). VF or asystole occurred in 10% of patients.
authors.affiliation: Institute of Cardiology, Warszawa Anin, Poland. lszumowski@ikard.pl
authors.forename: Lukasz
authors.initials: L
authors.lastname: Szumowski
authors.forename: Robert
authors.initials: R
authors.lastname: Bodalski
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Jedynak
authors.forename: Ewa
authors.initials: E
authors.lastname: Szufladowicz
authors.forename: Roman
authors.initials: R
authors.lastname: Kepski
authors.forename: Paweł
authors.initials: P
authors.lastname: Derejko
authors.forename: Piotr
authors.initials: P
authors.lastname: Urbanek
authors.forename: Ewa
authors.initials: E
authors.lastname: Michalak
authors.forename: Michał
authors.initials: M
authors.lastname: Orczykowski
authors.forename: Joanna
authors.initials: J
authors.lastname: Zakrzewska
authors.forename: Andrzej
authors.initials: A
authors.lastname: Przybylski
authors.forename: Franciszek
authors.initials: F
authors.lastname: Walczak
mesh_terms: D000293:Adolescent; D000328:Adult; D001281:Atrial Fibrillation / Q000209:etiology / Q000628:therapy; D001282:Atrial Flutter / Q000209:etiology / Q000628:therapy; D001283:Atrioventricular Node / Q000503:physiopathology / Q000601:surgery; D002037:Bundle-Branch Block / Q000209:etiology / Q000601:surgery; D017115:Catheter Ablation / Q000379:methods*; D015331:Cohort Studies; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011227:Pre-Excitation, Mahaim-Type / Q000150:complications* / Q000175:diagnosis / Q000601:surgery*; D011336:Probability; D012016:Reference Values; D018570:Risk Assessment; D012720:Severity of Illness Index; D013611:Tachycardia, Atrioventricular Nodal Reentry / Q000175:diagnosis / Q000209:etiology / Q000601:surgery*; D016896:Treatment Outcome