["Double nodal pathway" as a common electrogenic pathway at the base of first and second degree paroxysmal atrioventricular node and nodal reentrant tachycardia].

The combined occurrence of conduction disturbances and reentry in subjects with a dual atrioventricular nodal pathway is extremely rare and poorly documented, only by means of short electrocardiographic strips. This case report deals with a young woman with frequent episodes of paroxysmal first- and second-degree type I atrioventricular block due to a dual atrioventricular nodal pathway at Holter monitoring, and atrioventricular nodal reentrant tachycardia inducible at transesophageal electrophysiologic study. This case confirms that some paroxysmal first- and second-degree atrioventricular block and the atrioventricular nodal reentrant tachycardia may share the same electrogenetic substrate represented by a dual atrioventricular nodal pathway. This finding may be of clinical significance because of its potential therapeutical implications. Further studies are needed in order to explain the rarity of this association.