Abstract
Two to one bundle branch block (BBB) is a particular form of intermittent BBB in which beats showing high grade BBB alternate regularly with beats showing normal conduction [1–4]. It is physiologically equivalent to the much more common 2:1 A-V block. Both have been related to a critical increase of the heart rate in the presence of a prolonged refractory period, assuming that every other impulse falls on the refractory phase and is blocked, whereas the alternate beats fall after recovery has been completed and are normally conducted. However, we have previously suggested [5] that several varieties of 2:1 BBB may exist. Thus, when 25 cases were analyzed, the 2:1 BBB was found to occur in three different ways: 1) in relation to phase-3 block; 2) in relation to supernormal conduction; and 3) in relation to phase-4 block. In this study, we will stress the decisive role that concealed anterograde and retrograde conduction may play in the mechanism of these three varieties of 2:1 BBB.
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References
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© 1983 Martinus Nijhoff Publishers, The Hague
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Nau, G.J., Elizari, M.V., Rosenbaum, M.B. (1983). The Different Varieties of 2:1 Bundle Branch Block. In: Rosenbaum, M.B., Elizari, M.V. (eds) Frontiers of Cardiac Electrophysiology. Developments in Cardiovascular Medicine, vol 19. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-6781-6_25
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DOI: https://doi.org/10.1007/978-94-009-6781-6_25
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