|
|
| (One intermediate revision by the same user not shown) |
| Line 16: |
Line 16: |
|
| |
|
| [[Puzzle 2005_8_285 - Answer|Answer]] | | [[Puzzle 2005_8_285 - Answer|Answer]] |
| [[Image:Puzzle_2005_8_285_fig3.jpg|Figure 3|thumb]]
| |
| The above information should raise the suspicion of a
| |
| Mahaim fibre. This is an accessory pathway with AVnode-
| |
| like properties. Due to its decremental properties
| |
| preexcitation is subtle and may even be absent. The
| |
| Mahaim fibre only conducts in an antegrade fashion
| |
| and usually has a long course, extending from the free
| |
| wall of the right atrium across the tricuspid annulus to
| |
| the right bundle. Consequently, tachycardias run in
| |
| an antidromic direction and generally show an LBBB
| |
| morphology with a superior axis. Although the original
| |
| publications by Mahaim, who was a contemporary of
| |
| Wenckebach, were on nodoventricular and fasciculoventricular
| |
| fibres, his name survived all new insights
| |
| and nomenclature published thereafter and is still used
| |
| to paraphrase an entire family of accessory pathways
| |
| with AV-node-like behaviour.
| |
| In this patient the combination of subtle signs of
| |
| preexcitation in the resting ECG, absent Q wave in
| |
| leads I, V5 and V6, an RS in III and the wide QRS
| |
| tachycardia with LBBB morphology and left-axis
| |
| deviation is highly suggestive of the diagnosis of
| |
| Mahaim fibre. During invasive electrophysiological
| |
| testing a Mahaim fibre was identified running from the
| |
| anterior site of the tricuspid valve annulus to the distal
| |
| right bundle. The Mahaim bundle was successfully
| |
| ablated at the level of the annulus. The ECG shown in
| |
| figure 3 no longer reveals the subtle signs of abnormal
| |
| initial activation or preexcitation. During follow-up,
| |
| the patient remained free from symptoms.
| |
