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 E^
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.
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.
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.
- Figure 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.
8 Pulmonary Atresia and Intact Ventricular Septum 137
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central area of atretic valve rudimentary pulmonary valve leaflet
Figure 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 arteri-otomy 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.
formalin infill ratee patent ductus
Figure 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.
formalin infill ratee patent ductus
Figure 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.
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