In cyanotic heart diseases with restricted systemic blood flow (hypoplastic left heart syndrome, hypoplasia or interruption of the aortic arch, very severe coarctation), pulmonary blood flow is high, but systemic blood flow is dependent on the ductus arteriosus. Cyanosis is predominant in the lower part of the body (see Figure 14.16). Chronic hypoperfusion may result in splanchnic ischaemia and metabolic acidosis.

Ductal patency is essential for ensuring systemic perfusion and should be maintained with prostaglandins if necessary [2]. PVR must be high to limit excessive pulmonary blood flow and improve systemic blood flow: FiO₂ 0.2-0.3, slight respiratory acidosis through permissive hypercapnia, possible addition of CO₂ to the inspiratory circuit during CPB [1]. The subpulmonary ventricle often requires inotropic support due to volume overload.

 

 

Right → left shunt and Qs ↓ (Qp/Qs > 1.0)

Mixing of arterial and venous blood, insufficient systemic blood flow (LV or aortic arch hypoplasia), systemic perfusion ensured by the ductus arteriosus from the PA. Reduce SVR and increase PVR to balance the Qp/Qs ratio since the pulmonary circuit “steals” systemic blood flow.

© BETTEX D, BOEGLI Y, CHASSOT PG, June 2008, last update May 2018
 

 

 

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