[Paroxysmal tachycardia due to a latent Wolff-Parkinson-White syndrome]

The authors studied 35 cases of Bouveret type paroxysmal tachycardia with normal baseline ECB, without any signs of Wolff-Parkinson-White syndrome. In more than half the patients, it seems that it may be stated that the paroxysmal tachycardia is related not to a reciprocal intranodal rhythm, as is said classically, but to a reciprocal rhythm using in the anterograde direction the normal pathways and in a retrograde direction a direct atrio-ventricular bundle in which only retrograde conduction is possible. This explains the absence of any patent preexcitation pattern on tracings in sinus rhythm. The authors particularly stress the value of a sign recorded at the onset of an attack of tachycardia: transient slowing of the rate of the tachycardia when functional bundle branch block is present can only be explained by the existence of a latent preexcitation bundle on the side of the "slowing bundle branch block".