Compensating conduction times as a mechanism for alternation during reciprocating tachycardia

This paper reflects a hitherto undescribed mechanism for alternation of conduction time during supraventricular reciprocating tachycardia. Delayed anterograde conduction through an A-V nodal pathway effectively delays conduction of the reciprocal impulse to its retrograde course and hence to its intrajunctional reciprocal point: the point where it begins anterograde conduction once again. This section of the A-V nodal pathway consequently has a longer recovery time. The ensuing anterograde conduction is therefore faster and the ensuing cycle therefore shorter. The shorter ensuing cycle, in turn, means that the returning impulse reaches its intrajunctional reciprocal point earlier. There is consequently less time for recovery for the anterograde A-V nodal pathway. Hence the ensuing delay and longer cycle. This establishes a sequel of long and short cycles due to alternation of conduction.