[Junctional and atrioventricular paroxysmal reciprocating tachycardias: clinical and electrocardiographic characteristics (author's transl)].

Some clinical and electrocardiographic characteristics are reviewed in two groups of patients with paroxysmal junctional reciprocating tachycardia (JRT) (21 cases) and atrioventricular reciprocating tachycardia involving an atrioventricular bypass tract with unidirectional anterograde block (AVRT) (26 cases). Mechanisms of tachycardia were established in all cases by intracavitary electrophysiologic study. Mean age (+/- S.D.) was 46 +/- 18 yrs (range: 14-75) in the JRT group and 32 +/- 16 yrs (6-67) in the AVRT group (p < 0.02). Male/female ratio was 11/10 in the former and 15/11 in the latter. Mean tachycardia rate of the JRT was 178 +/- 24 b/min (130-215) vs. 205 +/- 21 b/min (160-240) of the AVRT (p < 0.001). Only in 4 cases of JRT a second degree A-V block was observed during tachycardia. P wave was recorded just after the end of QRS complex in all cases of AVRT; on the contrary it was completely hidden in the QRS complex in 11 cases (52%), partially superimposed on the end of QRS in 6 cases (29%) and on the beginning of QRS in 4 cases (19%) of the JRT group. A functional bundle branch block during tachycardia was observed only in 3 cases of JRT (14%) vs. 15 cases (58%) of AVRT. The block never induced any change in the tachycardia rate either in the JRT group or in those cases of AVRT with the anomalous pathway heterolateral to the bundle branch block. On the contrary, the block ipsilateral to the anomalous bypass tract constantly induced variations in cycle length during tachycardia. In conclusion, analysis of some clinical and electrocardiographic features may give useful information for the differential diagnosis of JRT and AVRT and so be helpful for a better therapeutic approach.