Mahaim fibre

Mahaim and Gander were the first to describe the so-called Mahaim fibres in 1947 (Lüderitz 1983).

Mahaim tachycardia is an accessory pathway that leads to an antidromic tachycardia - directed against the physiological course - and predominantly affects healthy hearts (Lewalter 2010 / Pinger 2019).

Depending on the place of origin and insertion, a distinction is made between the following fibres:

• atrio- fascicular
• nodofascicular
• nodo-ventricular (Herold 2020)

Mahaim-railways are rare. They are found in about 3% of all accessory pathways (Hluchy 2000). The disease usually occurs before the age of 30 (Pinger 2019).

Associated cardiac malformations: The disease may be associated with Ebstein' s disease (Pinger 2019). In addition, there are often other conduction disorders such as Kent type accessory conduction or dual AV node physiology (Hluchy 2000).

Mahaim fibres are a congenital disease in which there is embryonic dislocation of tissue of the AV node, the Purkinje system or the His bundle. It has its origin exclusively along the tricuspid valve annulus and runs into the myocardium of the right ventricle and the right fascicle system.

Mahaim fibers are atriofascicular pathways (Pinger 2019), which typically have antegrade, slow and delayed conduction properties (Kasper 2015).

• palpitations
• Dyspnea

(Weismüller 2000)

Rest ECG

The ECG only shows abnormalities in the seizure.

• Tachycardia
• Sinus rhythm
• PQ- time normal
• rarely a small delta wave occurs
• Left bundle branch block with QRS- duration of 120 - 140 ms (Pinger 2019)
• P- wave in front of the QRS- complex (Stierle 2017)

The treatment is initially carried out with medication

• Class Ia- Antiarrhythmics such as:
  • Quinidine ret.; recommended dosage: 2 x 500 mg / d
  • Procainamide: Dosage recommendation: 3 x 2 g - 3 g / d (Schmidt 2007)
• Class Ic-- antiarrhythmic agents such as:
  • Flecainide: Recommended dosage: 2 x 50 mg - 100 mg/d
  • Propafenone: Recommended dosage: 2 - 3 x 200 mg/d (Schmidt 2007)

Or to block the retrograde transition via the AV node:

• beta-blockers such as metoprolol, recommended dosage: 100 mg - 200 mg / d
• Calcium channel blockers such as Verapamil, recommended dosage: 80 mg - 120 mg / d (Schmidt 2007, Pinger 2019)

If the drug treatment does not respond, ablation is possible (Pinger 2019).

1. Herold G et al (2020) Internal medicine. Herold Publishing House 284
2. Hluchy J (2000) Mahaim fibers: electrophysiologic characteristics and radiofrequency ablation. Clin. Res. Cardiol. (89) 136 – 143
3. Kasper D L et al (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education 1481
4. Kasper D L et al (2015) Harrison's Internal Medicine. Georg Thieme Publisher 1809
5. Lewalter T et al (2010) Cardiac arrhythmias: Diagnosis and therapy. Springer Publishing House 264
6. Lüderitz B et al (1983) Handbook of Internal Medicine: Volume IX Heart and Circulation. Springer- Publishing House 27
7. Pinger S (2019) Repetitorium Kardiologie: For clinic, practice, specialist examination. German medical publisher. 673, 676
8. Schmidt (2007) Pharmacology and toxicology for study and practice. Schattauer publishing house 461
9. Stierle U et al (2014) Clinical Guide to Cardiology. Elsevier Urban and Fischer 425
10. Weismüller P et al (2000) Tachycardia with broad QRS complex in a young man. The internist (41) 1247 - 1252