[Bi-directional tachycardia of infrabundle of his origin. Arguments for reciprocal rhythm]

A new case of bi-directional tachycardia is reported. Intracavitary recordings show that the site of the disorder lies below the main trunk of the bundle if His. Analysis of the surface electrocardiogram and of electrical stimulation has led to a number of arguments for the hypothesis of a reentry circuit which uses the right branch in the reverse direction, and then the anterior and posterior sub-branches alternately in the normal direction. The recurrent attacks of tachycardia can be prevented by permanent ventricular stimulation at a rate above that which occurs between the attacks. However, the relief which this affords has not altered the prognosis of this arrhythmia, which remains very poor.