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The Hemi Fontan Procedure
The Hemi Fontan procedure simplifies the subsequent Fontan procedure (3). In fact,
Norwood and others have demonstrated that the Fontan can be completed after a
hemi Fontan in the catheterization laboratory by placement of a covered stent.
The principal arguments against the hemi Fontan procedure include the fact that
it involves extensive surgery in the region of the sinus node and sinus node artery
which might result in a higher incidence of late sinus node dysfunction. Furthermore
it should rarely be necessary to plasty the central pulmonary arteries if the stage 1
Norwood procedure has been performed in such a fashion as to permit normal growth
of this area.
Interval Management Between the Second and Third Stages
The child’s progress following second stage palliation is usually a remarkable contrast
to progress following neonatal palliation. Growth improves because of removal of the
volume loading of the neonatal circulation. Hypertension is common and frequently
requires treatment with an ACE inhibitor.
In the months following the second stage procedure the child is likely to show gradual
deterioration in arterial oxygen saturation. This may be a combination of venous
collateral vessels opening, growth of the child resulting in the head and upper half
of the body contributing less to the total systemic venous return and finally the
development of pulmonary arteiovenous malformations. It is generally prudent to
proceed to the Fontan procedure when the oxygen saturation is consistently less than
approximately 75%. Cardiac catheterization should be undertaken by 12 months from
the time of the second stage.
Should profuse collaterals be coil occluded at the time of pre-Fontan catheterization?
Some centers believe that it is helpful to occlude bother internal mammary arteries
as well as any other “chest wall collaterals” in order to reduce volume loading of the
single ventricle following the Fontan procedure.
Third Stage Palliation of Hypoplastic Left Heart Syndrome: The Fenestrated Fontan
A decision as to whether a child is a suitable candidate for the Fontan procedure is no
longer a difficult one. If the child is making reasonable progress with the bidirectional
Glenn shunt then almost certainly they will do well with a fenestrated Fontan procedure.
Fontan Procedure Utilizing an Extracardiac Conduit
Marcelleti and others (5) repopularized the use of an extracardiac conduit for the Fontan
procedure as was described by Fontan in his original description of the procedure.
The stimulus was a high incidence of supraventricular arrhythmias seen with the older
atriopulmonary type Fontan. However the extracardiac conduit has the disadvantage
that it does not incorporate growth potential. Another important disadvantage is that