Discussion:
There are several techniques to create confluence and enlarge the branch
PAs. These include enlargement with autologous pericardium (fresh /
pre-treated), bovine pericardium, Gore-Tex patch / tube, Dacron grafts,
homografts and resection with direct end to end
anastomosis1. However, all of these techniques have a
high rate of restenosis which is largely attributed to extension of
ductal tissue into the branch PAs, scarring, fibrosis and cicatrization
of autologous pericardium2,3,4.
Our patient had an unusual presentation. Though the pulmonary arterial
supply was sparse, the size of both the branch PAs at the hilum was
generous. It is likely that the ductal flow during infancy and early
childhood helped the growth of the branch PAs. Subsequently, the PDA
gradually constricted along with the constriction of LPA origin
resulting in progressive reduction of the pulmonary blood flow causing
decreased effort tolerance and worsening cyanosis. Such late
presentations are not uncommon in our part of the world.
The resection and end-to-end anastomosis or pericardial patch
augmentation would have been conventional wisdom. Instead, we thought of
recruiting the normal sized MPA which was lying in close proximity and
had no clinical value. The pulmonary end of the transected MPA was
turned down as an extension to create a tension free, tissue-tissue
anastomosis between the branch PAs with the confluence. This was made
possible due to the presence of a normal MPA above the atretic pulmonary
valve. In order to avoid torsion while turning down the transected MPA
towards the left hilum, two marker sutures were placed in opposing
directions for identification after transection of MPA. Being native
autologous tissue, it is resistant to infection and calcification, is
free from autoimmune responses and has distensibility and potential for
growth unlike other biological or prosthetic materials. However, the use
of MPA to create a confluence is possible only in a select subset of
patients with univentricular hearts or pulmonary atresia where it can be
safely sacrificed as was the case in our patient.