The pulmonary venous wedge pressure in pulmonary arterial hypertension

The comparability of the main pulmonary artery pressure (PAP) and the pulmonary venous wedge pressure (PVWP) was assessed during cardiac catheterization in 89 patients with pulmonary artery hypertension (PAH) and increased pulmonary blood flow. Preliminary evaluation revealed a wide disparity between the 2 determinations. Fifty-five pull-back pressure recordings from branch-to-main pulmonary artery were analyzed. Twenty-four percent (13/55) had systolic pressure gradients >20 mm Hg. between branch and main pulmonary artery. When PVWP and only ipsilateral branch PAP were compared (n=48), diastolic and mean (m), but not systolic PVWP, correlated closely with branch PAP (r=0.77, r=0.73 and r=0.59, respectively). In 46 of 48 patients the PVWP_m was not significantly greater than the ipsilateral PAP. Twenty-nine of 30 patients with PVWP_m <30 mm Hg. had an ipsilateral PAP_m <40 mm Hg. In 15 patients with PVWP_m between 30 and 39 mm Hg, there was a wide range (30–59 mm Hg) of PAP_m. Three patients with PVWP_m >40 mm Hg. had severe PAH. It is concluded that: 1) hemodynamically significant branch-to-main PAP gradients are present in some patients with PAH and may result in erroneously high pulmonary arteriolar vascular resistance when calculated from main PAP; 2) properly performed PVWP determination can define the lower limit of mean pressure in the ipsilateral branch pulmonary artery; 3) a PVWP_m <30 mm Hg. usually indicates an ipsilateral PAP_m <40 mm Hg; 4) a PVWP_m >30 mm Hg. is compatible with either moderate or severe PAH; 5) correlation of PVWP with PAP is not related to pulmonary blood flow.