tıklayınız - Türk Pediatrik Kardiyoloji ve Kalp Cerrahisi Derneği

Stage 2 Palliation
Connection of the superior vena cava to the pulmonary arteries eliminates the inherent
inefficiency that is present following the stage 1 Norwood procedure. The circulation
is inefficient following the stage 1 procedure because of recirculation of pulmonary
venous return through the lungs. Because only systemic venous return passes through
the pulmonary circulation following a bidirectional Glenn the volume loading of the
ventricle is effectively eliminated.
Timing
Experience suggests that beyond 2.5 to 3 months the pulmonary resistance is
sufficiently low to allow a successful second stage procedure but the postoperative
course tends to be smoother and more rapid if the second stage is deferred until 4 or 5
months (1). There appears to be no advantage in delaying beyond 6 months. With a 5
mm Sano shunt it is more likely that a child will have an unacceptable level of cyanosis
e.g. saturation less than 70 to 75% by 2.5 to 3 months and will require an earlier second
stage.
Should supplementary pulmonary blood flow be left?
The advantage of leaving supplementary pulmonary blood flow in addition to the
bidirectional Glenn shunt is that this will permit perfusion of the lungs with the
presumed hepatic factor which inhibits development of pulmonary arteriovenous
malformations. However from a technical perspective there is insufficient room on the
right pulmonary artery to accommodate both a modified right Blalock shunt and a
bidirectional Glenn shunt. On the other hand it would be technically feasible to leave
a Sano shunt in conjunction with a bidirectional Glenn shunt.
The principal argument against leaving supplementary pulmonary blood flow is that this
additional blood flow is inherently inefficient. Furthermore it is difficult to quantitate
the amount of supplementary blood flow so that there is a risk of over volume loading
the single right ventricle. Studies which have compared patients with and without
supplementary pulmonary blood flow suggest a higher incidence of pleural effusions,
longer hospitalization and the suggestion of a higher mortality when additional blood
flow is left (2).
Technique of the Bidirectional Glenn Shunt
Although it is feasible to undertake a bidirectional Glenn shunt without cardiopulmonary
bypass using either no temporary shunt around the anastomosis or with a temporary
shunt, nevertheless it is our recommendation that the bidirectional Glenn shunt
should be performed on cardiopulmonary bypass without aortic cross clamping. The
cardiac end of the divided SVC is oversewn and the cephalic end is anastomosed to
a longitudinal arteriotomy on the superior surface of the proximal right pulmonary
artery. The Sano shunt is taken down.
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