The Glenn shunt, also known as Glenn procedure, is a palliative surgical procedure for a variety of cyanotic congenital heart diseases.
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Rationale
In this procedure, the systemic venous return is re-directed to the pulmonary circulation, bypassing the right heart 1-3.
It can be used in a variety of situations, including:
- cyanotic congenital cardiac anomalies that eventually lead to a single anatomical or functional ventricle (i.e. tricuspid atresia)
- right or left ventricular hypoplasia (i.e. hypoplastic left heart syndrome)
- as an initial step before the Fontan form of a total right heart bypass
Procedure
The classic (unidirectional) Glenn shunt involved:
- ligation of the distal end of the superior vena cava (SVC)
- anastomosis of the side of the SVC above the ligation with the distal end of the divided right pulmonary artery, providing unilateral (right) lung perfusion
In a modified (bidirectional) Glenn or hemi-Fontan shunt, anastomosis is created between the transected end of the SVC and the side of the undivided right pulmonary artery, providing balanced bilateral pulmonary circulation 1-3.
The Glenn shunt is now considered the first stage of a complete systemic venous to the pulmonary arterial anastomosis, also known as a Fontan procedure. The Fontan procedure is basically a bidirectional Glenn shunt combined with a conduit or tunnel through or around the right atrium, shunting blood from the inferior vena cava to the pulmonary arteries.
Complications
Complications of the Glenn shunt include 2-4:
- SVC syndrome
- shunt and pulmonary artery thrombosis
- stenosis of the cavopulmonary anastomosis
- sinus node injury with subsequent rhythm disturbance
- pulmonary arteriovenous malformation (AVM)
- aortopulmonary collaterals
History and etymology
The Glenn shunt was introduced in 1958 by Dr William Glenn and modifications to the procedure were published by Dr Gaetano Azzolina in 1973 5-6.