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.