Single Ventricle

Single ventricle is a congenital defect in which one ventricle of the heart is abnormally small (hypoplastic). The other ventricle, which is normal sized, is referred to as the single ventricle. This defect is usually accompanied by an atrial septal defect (ASD) and often pulmonary outflow obstruction. There are many forms of single ventricle, resulting in different types of cardiac functional abnormalities.

This condition can be surgically corrected. First, when there is pulmonary outflow obstruction a modified Blalock-Taussig shunt can be placed during infancy to allow blood to flow from the innominate artery into the pulmonary artery and to the lungs (see fig. 2). A bi-directional Glenn shunt is then performed later in the first year of life to suture the end of the superior vena cava to the right pulmonary artery. The modified Blalock-Taussig shunt is tied off (see fig. 3). Still later, a Fontan procedure is performed to connect the inferior vena cava to the right pulmonary artery (see fig. 4). In this illustration, an extra-cardiac conduit technique is used. Blood flow to the lungs is then restored.

Figure 1: Cut away view of the normal heart.
Figure 2: Heart with single ventricle defect with a modified Blalock-Taussig shunt.
Figure 3: Heart with bi-directional Glenn shunt and Blalock-Taussig shunt tied off.
Figure 4: Finished surgical repair with Fontan procedure.


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