Download o Pulmonary Atresia and Intact Ventricular Septum

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Pulmonary Atresia and Intact
Ventricular Septum
Infants born with this anomaly have inadequate pulmonary blood flow (caused
by pulmonary valve atresia) and severe right ventricular hypertension, unless tricuspid insufficiency allows decompression of the ventricle. Initial resuscitation
includes maintenance of ductus arteriosus patency with prostaglandin Ei.
Right ventricular size may vary from severe hypoplasia to a near normal size,
depending on when in fetal development the pulmonary valve became atretic. If
it was late in cardiac development, the chance is greater that the right ventricle
will be larger at birth. Generally, hypoplasia of the tricuspid valve is proportional
to the size of the right ventricular inlet.
Ideal surgical palliation is aimed at increasing pulmonary blood flow and
relieving right ventricular hypertension. If the tricuspid valve is of satisfactory
size and the right ventricle is at least 30% to 40% of normal in size, a valvectomy
alone may result in successful palliation. If the tricuspid valve is restrictive and/or
the right ventricle is severely hypoplastic, an isolated valvectomy may not provide
palliation and a systemic to pulmonary artery shunt will be necessary also. In this
case, a nonrestrictive atrial septal defect (ASD) must be naturally present or
created by balloon septostomy. In many centers, balloon valvuloplasty is performed in the cardiac catheterization laboratory after laser perforation of the
valve membrane. If successful, only a surgical shunt is needed when smaller right
ventricle (RV) size or decreased compliance results in inadequate pulmonary
blood flow.
After initial palliation, adequate right ventricular growth may allow a later
two-ventricle repair. If the right ventricle remains severely hypoplastic, patients
are candidates for a one-ventricle repair (Fontan procedure).
In infants with inadequate pulmonary blood flow after pulmonary valvectomy
alone, long-term ductus patency may mitigate the need for a surgical shunt. This
may be accomplished by Formalin infiltration of the patent ductus. Right ventricular compliance usually improves with time, and ductal patency for a period
of days or weeks following valvectomy may provide satisfactory pulmonary blood
flow until the right ventricle recovers. Otherwise a systemic to pulmonary artery
shunt will be needed.
135
136 Color Atlas of Congenital Heart Surgery
PA view
Lateral View
right
ventricular
inlet
FIGURE 8-1. Right ventriculogram in an infant with severe right ventricular hypoplasia.
The outlet portion of the ventricle is underdeveloped, and the tricuspid valve annulus is
hypoplastic. This baby is not a candidate for valvectomy alone.
right
ventricular
outlet
right
ventricular
inlet
8-2. Lateral view of right ventriculogram in an infant with a near normal-size right
ventricle. The tricuspid valve annulus and the outlet portion of the ventricle are well developed. A valvectomy is appropriate for this baby.
FIGURE
8
Pulmonary Atresia and Intact Ventricular Septum 137
central area
of atretic valve
rudimentary
pulmonary
valve leaflet
ceph
->L
R<-
caud
8-3. This heart is prepared for a pulmonic valvectomy. On cardiopulmonary
bypass, a side-biting clamp is placed on the proximal main pulmonary artery. An arteriotomy is made, and stay sutures are inserted. A snare is pulled tight around the distal main
pulmonary artery, and the clamp is removed. There is hemostasis, and the atretic valve
membrane is visualized. The rudimentary commissures and leaflets are seen encircling the
atretic central portion of the membrane. The atretic pulmonary valve membrane is now
excised. More commonly, the pulmonary valve annulus is restrictive and a transannular
outflow tract patch is needed.
FIGURE
formalin infiltrated
patent ductus
ceph
R««-
-•L
caud
8-4. In this infant, Formalin infiltration of the patent ductus is performed. Methylene blue is mixed with 4% Formalin so that the material is easily seen when injected in
tissues. A #30 needle is used with a 1-cc tuberculin syringe for precise injection in the wall
of the ductus. When they are compared, a glass syringe is better than a plastic syringe,
because the glass plunger slides more easily. The ductus wall is infiltrated over two thirds
of the circumference and much of the length of the ductal structure.
FIGURE