Ratio of total pulmonary blood flow to total systemic blood flow [Qp/Qs] ratio > 1 indicates
[A] No shunting
[B] Left-to-right shunt
[C] Right-to-left shunt
[D] Tetralogy of Fallot
- Qp/Qs ratio of >1:1 indicates that pulmonary flow exceeds systemic flow and defines a net left-to-right shunt.
- Qp/Qs ratio of < 1:1 indicates a net right-to-left shunt.
- Both left-to-right and right-to-left (bidirectional) shunting may be present in the same patient. If the left-to-right shunt equals the right-to-left shunt in magnitude, it is possible to have a Qp/Qs of exactly 1:1