Discussion
Despite surgical technical improvement, arrhythmic burden still represent a significant complication affecting the follow up of Fontan patients. [3, 4] The effect of cavo-pulmonary anastomosis modification on the incidence of arrhythmias is controversial, in particular the extra cardiac total cavopulmonary connection does not obviate the occurrence of sinus node dysfunction. [4] The clinical impact of this condition is often underestimated as bradycardia is usually deemed to be well tolerated in the context of Fontan circulation, particularly in the presence of an escaping junctional rhythm. Junctional rhythm in patients with Fontan circulation, by increasing the atrial pressure blunts the passive driving force of the Fontan circuit. [2]
This cases provide the echocardiographic proof of the correlation between postoperative retroconducted junctional rhythm and acute Fontan failure, which was completely reversible after atrial pacing.
It should be underscored that atrial activity retroconduction, differently from dissociated junctional rhythm, by generating a rhythmic abnormal increase of atrial pressure, is one of the the most important pathogenic determinants responsible for Fontan circulation failure in this clinical setting.