The relationship of pulmonary venous wedge to pulmonary arterial pressures

A comparison of pressure levels and pressure-time relationships in pulmonary artery pressure (PAP) and pulmonary venous wedge pressure (PVWP) tracings was made from cardiac catheterization records of 60 patients, aged 1 day to 16 years. In 50 patients with normal or low PAP's there was close correlation between systolic, diastolic, and mean pressures in the two sites. In all 10 patients with pulmonary hypertension the PVWP's were elevated but were significantly different from corresponding PAP's. The wave contours showed qualitative similarities in most cases, but the duration of the rise in systolic pressure was longer, and the Q-pressure intervals were delayed in the PVWP tracings. Satisfactory PVWP's were obtained in 42 of 67 (63%) consecutive patients approached from the leg. Lack of correlation of pressures from the two sites in the presence of pulmonary hypertension may be attributed, in part, to decreased compliance of the pulmonary arterial system. It is concluded that the PVWP is useful in catheter evaluation of heart disease: when the PVWP is normal it usually reflects accurately the PAP; an elevated PVWP suggests an elevated PAP but cannot be used reliably as an indication of the actual arterial pressure.