Mixing of blood in Single Ventricle Physiology can occur at three levels:
Atrial level mixing (PFO, ASD)
o At times, this must be emergently established via balloon septostomy
Ventricular level mixing (VSD)
Ductal level mixing (PDA)
o The most common way to provide appropriate mixing is via Prostaglandin
E1 infusion (dose 0.01 – 0.05 mcg/kg/min)
Single Ventricle Physiology can result from:
Systemic (Left-Sided) Outflow Obstruction
o Examples include:
Hypoplastic Left Heart Syndrome
Critical Aortic Stenosis
Interrupted Aortic Arch
o In such situations, Qs is primarily dependent on a R L ductal shunt.
The amount of shunt flow depends on relative pulmonary vascular resistance (PVR)
and systemic vascular resistance (SVR). As PVR drops after birth, Qp will increase at
the expense of Qs.
o If this condition is not diagnosed prenatally, these babies will often present
in cardiogenic shock when their PDA closes.
Pulmonary (Right-Sided) Outflow Obstruction