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Supernormal Conduction in the Left Bundle Branch Unmasked by the Linking Phenomenon
Author(s) -
LUZZA FRANCESCO,
ORETO GIUSEPPE,
DONATO ANTONINO,
SATULLO GAETANO,
SCIMONE IGNAZIO M.
Publication year - 1992
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1992.tb03135.x
Subject(s) - medicine , left bundle branch block , cardiology , electrical conduction system of the heart , bundle , bundle of his , phenomenon , bundle branch block , electrocardiography , heart failure , epistemology , philosophy , materials science , composite material
This presentation reflects a case of phase‐3 left bundle branch block (LBBB). Analysis reveals that relatively early QRS complexes are wide, whereas beats occurring later than a critical time are narrow. There are, however, two unexpected phenomena: (1) an overlap occurs between the range of R‐R intervals resulting in normal intraventricular conduction and the range of R‐R intervals resulting in LBBB pattern. Complexes that follow a wide beat are often wide although they are associated with relatively long R‐R intervals, whereas complexes that follow a normal beat tend to be normal even after relatively short R‐R cycles. This is due to concealed retrograde penetration of the bundle branch that is blocked in anterograde direction (the so‐called linking phenomenon). (2) Some early supraventricular impulses, paradoxically, resulted in normal intraventricular conduction. The phenomenon is a manifestation of supernormal LBB conduction, and only occurs following a wide QRS complex associated with retrograde activation of the LBB. The linking phenomenon reveals or unmasks the supernormal phase of LBB conduction. Following a retrograde and delayed activation of the LBB, the refractory period of the bundle branch is postponed, in such a way that a supraventricular impulse is allowed to occur during the early phase of supernormal conduction.