Qp:Qs ratio
The ratio of pulmonary blood flow to systemic blood flow, used to quantify left-to-right shunting in congenital heart disease.
Full Definition
The Qp:Qs ratio compares pulmonary blood flow (Qp) to systemic blood flow (Qs) and is a fundamental hemodynamic measurement in pediatric cardiology. A normal ratio is 1:1, indicating equal flow to both circulations. Ratios greater than 1.5:1 typically indicate significant left-to-right shunting that may require intervention. This calculation is essential for determining the hemodynamic significance of septal defects, patent ductus arteriosus, and other shunt lesions. The ratio helps guide timing of surgical repair and assess the risk of developing pulmonary vascular disease.
Usage
Usage note: Always express as a ratio (e.g., 2.1:1) rather than a decimal.
In Context
- "Cardiac catheterization revealed a Qp:Qs ratio of 2.1:1, indicating significant left-to-right shunting." — catheterization report
- "The large ventricular septal defect resulted in a Qp:Qs ratio of 3:1 with evidence of volume overload." — echocardiogram report