Quantitation of the effective right ventricular output in patients with pulmonary atresia and intact ventricular septum after placement of a right ventricular outflow patch and an aorticopulmonary shunt

A mathematical derivation is presented of an equation that allows quantitation, in the cardiac catheterization laboratory, of the effective output of the right ventricle (Q_RV) in patients with pulmonary atresia and intact ventricular septum (PA/IVS) after palliation with a right ventricular outflow patch and an aorticopulmonary shunt. This derivation is based on the Fick principle and accounts for that portion of the right-to-left atrial shunt that flows through the aorticopulmonary shunt to the lungs and thus contributes to the effective pulmonary blood flow (Q_ep). This equation relates Q_RV to pulmonary blood flow (Q_p), systemic cardiac output (Q_s), and Q_ep by Q_RV = Q_p + Q_s - (Q_p)(Q_s)/Q_ep. By providing an assessment of right ventricular function, this equation may be helpful in determining the suitability of the right ventricle to support biventricular repair. © 1994 Wiley-Liss,Inc..