Electrophysiological hall mark of intra Hisian block

What is the electrophysiological hall mark of intra Hisian block?

Electrophysiological hall mark of intra Hisian block is split His potential. The escape focus is slower in case of intra Hisian block than supra Hisian block. Intra Hisian block means conduction block within the bundle of His.

On the surface electrocardiogram, a narrow QRS complex is compatible with an atrioventricular nodal or intra His problem. Wide QRS complex may still occur in supra Hisian problems if there is wide QRS complex due to pre-existing bundle branch block [1].

About 70% of type II second degree AV block are associated with bundle branch block of which 30% are associated with a narrow QRS complex. These latter are due to problems within the His bundle [2].

Split H potentials on programmed atrial stimulation in patients without infranodal block has also been reported [1]. These patients were followed up for 10 to 41 months (average 21.4 months) during which clinical and ECG parameters remained stable.

References

  1. Demosthenes G Katritsis, Mark E Josephson. Electrophysiological Testing for the Investigation of Bradycardias. Arrhythm Electrophysiol Rev. 2017 Apr;6(1):24-28.
  2. S S Barold, D L Hayes. Second-degree atrioventricular Block: A Reappraisal. Mayo Clin Proc. 2001 Jan;76(1):44-57.
  3. C Sebag, G Motté, P Pariente, J M Davy. Fragmenting of the His Potential After Atrial Stimulation, Arch Mal Coeur Vaiss. 1981 Jun;74(6):705-17.