Pulmonic stenosis severity in children as determined by the pressure gradient

PS: pulmonic stenosis; MIG: maximum instantaneous gradient.
* Severity of PS is determined by the pressure gradient across the pulmonary valve, which is estimated noninvasively with echocardiography. The definitions provided here are based on the MIG, measured via Doppler echocardiography. PS severity can also be determined by cardiac catheterization, measuring the peak-to-peak gradient. However, in the modern era, cardiac catheterization is primarily used for therapeutic intervention and is rarely performed solely for diagnostic purposes in children with PS. There is generally good correlation between the Doppler-derived gradient and that obtained by direct catheterization measurements. However, because cardiac catheterization is typically performed with the patient sedated, catheter measurements are typically lower than corresponding echocardiographic estimates (eg, a catheterization measurement of 40 mmHg in a sedated patient corresponds roughly to a Doppler-derived gradient of 60 mmHg in an awake patient).