The Interrelations of the Pulmonary Arterial and Venous Wedge Pressures

Abstract

Pulmonary venous wedge pressure closely reflects the pulmonarj' arterial mean pressure. Pulmonarj' arterial wedge pressure is not significantly different from the left atrial mean pressure. Neither the former nor the latter is an approxinmtion of the pulmonarj' capillary pressure.A PRESSURE recorded through a cardiac catheter wedged tightly in a small . pulmonary artery has been referred to as a "capillary," "venous" or "wedge" pressure. On the other hand, a pressure recorded through a cardiac catheter wedged into a pulmonary vein during thoracotomy and in intact animals has been referred to as a pulmonary venous wedge pressure' 1! .Some investigators have found good correlation between the mean pulmonary arterial wedge pressure and the mean left atrial pressure in man and other animals; others have found great variability. A thorough analysis of the data and methods of each group of investigators reveals differences in technics with which the data were obtained, and in methods of statistical analyses.The purpose of this study was to show the relationship between pulmonary arterial wedge pressure and mean left atrial pressure on the one hand, and the pulmonary venous wedge pressure and mean pulmonary arterial pressure on the other. Determinations were made in normal dogs with the thorax open so that catheters could be placed precisely in the desired position. METHODThis study was done in 24 normal dogs. Pulmonarj' arterial wedge pressures were obtained by wedging into a small pulmonary arterial branch a 7 F cardiac catheter with one hole in the tip and pulmonarj' venous wedge pressures by wedging a catheter into a small branch of a pulmonary vein in From the Department of Medicine of the Southwestern Medical School of the University of Texas and tho Veterans Administration Hospitals, McKinney, Texas and Minneapolis, Minnesota.the same lobe of the lung ( fig. 1). Seven-F catheters with three holes in the tips were placed into the left atrium through a small pulmonarj' vein and into the pulmonarj' arterj' through a small pulmonarj' arterial branch ( fig. 1). The catheters were attached to Lundy stopcocks so that pressures from the different vascular and cardiac chambers could be recorded simultaneouslj' or in rapid sequence. Pressures were recorded with the chest closed and open by calibrated Statham strain gauges on a 4-channel Sanborn recorder. The superior surface of the presenting left atrium was taken as the zero level. RESULTSPulmonary arterial wedge pressures ranged from 0.2 to 14.8 mm. Hg. and left atrial pressures from 0.6 to 15.4 mm. Hg. There was a highly significant correlation between the means of the pulmonarj' arterial wedge and left atrial pressures ( fig. 2); r = 0.9577, p < 0.01. There was no significant difference in the difference between the means of the left atrial and pulmonary arterial wedge pressure; t = 0.7700 and p > 0.4. A lobar pulmonary venous branch was ligated and the pressure recorded in the pulmonarj' arterial wedge was of the same order of magnitude as the pulmonary arterial mean ...

Estimation of pulmonary artery pressure from pulmonary vein wedge pressure

“…The time lag, observed by the fluid-filled catheter system, ranged from 70 to 110 msec with a mean of 88 2 14 msec. We also confirmed the observation by Wilson et al [3,4] that the mean PVWP correlated well with the mean PAP. In addition, we have made the following new observations: 1) the diastolic PVWP was identical to the diastolic PAP; 2) disparity between PAP and PVWP in their systolic and mean values are correlated well with pressure difference between the diastolic PVWP and the mean LAP pressures; and 3 ) the systolic and the mean PAP could be accurately estimated from measurement of PVWP and LAP pressures.…”

The efficacy of using pulmonary vein wedge pressure for the estimation of pulmonary artery pressure in children with congenital heart disease

“…It seems reasonable to assume that their catheters were inadequately wedged. Wilson et al [1] recorded PAP and PVWP in four cases with normal PAP and five cases with pulmonary hypertension, and there was reasonable agreement between the mean pressures. Rao and Sissman [4] observed 50 patients with normal PAP and 10 patients with elevated PAP.…”

“…When the pulmonary artery is not entered in the patients with complex congenital heart disease, a pulmonary venous wedge pressure (PVWP) is recorded to be taken as the PAP. Although PVWP usually reflects PAP when the PVWP is within normal limit [1][2][3][4][5], there is little published data on the applicability and feasibility of PVWP in assessing Fontan candidates with low pulmonary blood flow and pulmonary blood pressure [6]. The purpose of this study is to investigate the relationship between PVWP and PAP in various congenital heart disease, including complex heart disease.…”

Effects of Blood Flow and Left Atrial Pressure on Pulmonary Venous Resistance

“…There have been similar discussions on the significance of the pulmonary venous wedge pressure. Wilson et al 11 and Haddy et al 10 In our experiments, small catheters were inserted as far as possible into a pulmonary venule. The rapid fall of pressure after injection of a small volume of fluid into these venular catheters demonstrated their patency, indicating: that pressures obtained in this system represented those at the catheter tip; such pressures are not venous '' wedge'' pressures since these small flexible catheters are technically difficult to place in a "wedge" position.…”

“…The pulmonary arterial wedge pressure is sometimes considered to represent the intracapillary as well as the capillary venous pres- 10 and Wilson et al 11 have held that the. pulmonary arterial wedge pressure is approximately equal to the mean left atrial pressure.…”