Estimation of pulmonary artery pressure from pulmonary vein wedge pressure

Correlations between pulmonary artery and pulmonary vein wedge pressures were investigated in 13 patients with atrial septal defect and 1 patient with Tetralogy of Fallot. Pulmonary vein wedge pressure wave form resembled that of pulmonary artery pressure, and the former lagged behind the latter by 70 to 110 msec (mean 88 ± 14) as observed by the fluid-filled catheter system. Diastolic pulmonary artery and diastolic pulmonary vein wedge pressures were nearly identical. Although systolic and mean pulmonary artery pressures correlated well with respective pulmonary vein wedge pressures, there were discrepancies when systolic and mean pulmonary artery pressure exceeded 35 and 20 mm Hg, respectively. However, systolic and mean pulmonary artery pressures could be estimated by adding the difference between the diastolic pulmonary vein wedge pressure and the mean left atrial pressure to corresponding systolic or mean pulmonary artery pressure. In conclusion, pulmonary artery pressures can be estimated by measuring pulmonary vein wedge pressures and the mean left atrial pressure.     

Pulmonary venous pressure: relationship to pulmonary artery, pulmonary wedge, and left atrial pressure in normal, lightly sedated dogs.

Because pulmonary venous pressure has never been measured, it is unclear whether pulmonary wedge pressure measures left atrial pressure, as commonly assumed, or pressure more upstream in the pulmonary venous or capillary beds. Fluid-filled mean pulmonary artery and pulmonary wedge pressure were compared with pulmonary venous and left atrial pressure obtained with high-fidelity micromanometer catheters in eight lightly sedated dogs over a physiologic range of filling pressures. In all conditions, mean pulmonary wedge pressure was virtually identical (r = 0.99) to mean left atrial pressure (slope = 0.99; intercept = -0.46 mm Hg). At the same time, mean pulmonary venous pressure (17.1 +/- 6.5 mm Hg) was intermediate between mean pulmonary artery pressure (20.2 +/- 6.2 mm Hg) and mean pulmonary wedge pressure (13.3 +/- 6.2 mm Hg; P < 0.0001) or mean left atrial pressure (13.4 +/- 6.3 mm Hg; P < 0.0001). These relationships were maintained over normal and increased pressure ranges. As measured by conventional flow-directed pulmonary catheters, mean pulmonary wedge pressure accurately reflects left atrial pressure in lightly sedated, spontaneously breathing normal dogs.     

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

The objectives of this study were to assess the accuracy of pulmonary vein wedge pressure (PVWP) in estimating pulmonary artery pressure (PAP) in various types of congenital heart disease, including single-ventricle physiology. The systolic, diastolic, and mean values of both PAPs and PVWPs were measured in 30 patients (a total of 46 points). Pulmonary artery pressure ranged from 13 to 74 (34 +/- 15) mm Hg in systole, 5 to 25 (13 +/- 6) mm Hg in diastole, and 6 to 48 (18 +/- 10) mm Hg in mean. As a whole, good correlations between PAPs and PVWPs were observed (systole, r = 0.70; diastole, r = 0.85; mean, r = 0.82; P < 0.0001). However, with an increase in PAP, the discrepancy between PAPs and PVWPs increased. When the mean PVWP was more than 18 mm Hg, the mean PVWP in 14 of 24 (58%) underestimated the mean PAP by up to 22 mm Hg (mean difference, -1.7 +/- 5.8 mm Hg). On the other hand, all of the patients with mean PVWPs less than 18 mm Hg (n = 22) had mean PAPs less than 18 mm Hg (r = 0.86; PAP = 1.11 x PVWP - 1.41; P < 0.0001), and the mean difference was -0.2 +/- 1.8 mm Hg. The mean PVWP can accurately estimate the mean PAP in children with congenital heart disease who have a mean PVWP less than 18 mm Hg.     

A fluoroscopic method to confirm proper catheter position to measure pulmonary artery wedge pressure

The proper position of a catheter to measure pulmonary wedge pressure is usually confirmed by measuring the oxygen saturation of withdrawn blood. However, this method of confirmation is tedious and frequently unsuccessful. A fluoroscopic method to confirm proper catheter position to measure wedge pressure was tested. Between 2 and 5 ml of contrast medium was injected into the artery distal to the catheter tip. Lack of movement for 15 seconds after injection indicated proper catheter position. As judged by the saturation of withdrawn blood and by comparison of wedge and left atrial or ventricular pressure, the fluoroscopic method of confirmation was correct in 71/75 attempts. Thus the flouroscopic method of confirmation of proper catheter position is simple, rapid, and reliable.     

A novel method to estimate pulmonary artery wedge pressure using the downslope of the Doppler mitral regurgitant velocity profile

Continuous-wave (CW) Doppler recording of mitral regurgitation (MR) is a reflection of the left ventriculoatrial pressure gradient. Accordingly, this jet may yield information about pulmonary artery wedge pressure (PAWP). In this study, we derived and then evaluated a novel method for prediction of PAWP. Patients (n=80) with moderate to severe MR and left ventricular dysfunction were included in the study. Transthoracic echocardiography was performed in patients during pulmonary artery pressure monitoring. A satisfactory CW Doppler recording of MR was obtained in 63/80 (78%). On the late descending portion of the CW recording, the time from a velocity of 4 m/sec to the end of the jet was defined as t1, and from 3 m/sec to the end of the jet as t2. Mathematical derivation of t1/t2 as a predictor of PAWP, was performed based on Weiss' derivation. If t1/t2 was <1.30, the PAWP was normal. If t1/t2 > 1.44, the PAWP was > 16 mmHg. With this new mathematical derivation, it appears that the downslope of the CW Doppler MR waveform may be able to distinguish a normal from elevated PAWP.     

Overestimation of mitral valve gradients obtained by phasic pulmonary capillary wedge pressure

We investigated the relationship between left atrial (LA) and pulmonary capillary wedge pressure (PCW) in order to define the clinical settings in which PCW may be used to approximate LA pressure and to determine the cause and significance of difference between LA and PCW pressures. Nineteen patients who at cardiac catheterization had LA, PCW, and left ventricular (LV) pressures recorded, had mitral valve gradients and areas determined. Mean PCW and LA pressures correlated well (r = 0.94). Phasic PCW consistently overestimated the MV gradient and underestimated the MV area compared to LA pressure, (8 ± 4 versus 4 ± 3 mm Hg, p < 0.001, 1.3 ± 0.3 versus 1.6 ± 0.3 cm², p < 0.005, respectively). Three patients had abnormal MV prosthesis function assessed by PCW pressure but not by LA pressure. Diastolic MV gradients between PCW and LV were caused or increased by a slowed y descent in the PCW tracing. Using the PCW pressure may falsely elevate MV gradients and falsely reduce MV areas and lead to incorrect clinical action.     

Noninvasive estimation of pulmonary capillary wedge pressure by color M-mode Doppler echocardiography in patients with acute myocardial infarction

The peak early diastolic filling velocity/flow propagation velocity (E/FPV) by color M-mode Doppler provides a better estimate of pulmonary capillary wedge pressure (PCWP) than transmitral or pulmonary venous flow. However, the value of E/FPV for the assessment of PCWP has not been evaluated in patients with acute myocardial infarction. We investigated the correlation between E/FPV and PCWP and whether PCWP can be estimated from E/FPV in patients with acute myocardial infarction. One hundred and two patients with acute myocardial infarction were divided into two groups. The first 60 patients were used to generate an equation to estimate PCWP (retrospective group). This equation was then assessed prospectively in the remaining 42 patients (prospective group). We measured the transmitral flow velocity indices and the deceleration time of diastolic pulmonary venous flow and E/FPV by Doppler echocardiography and compared these variables with PCWP measured using a pulmonary artery catheter. E/FPV was strongly correlated with PCWP (r = 0.89) in the retrospective group. The sensitivity of an E/FPV of > or = 2.0 for predicting a PCWP of > or = 18 mmHg was 95%, and the specificity was 98%. The estimated PCWP showed a strong correlation with the measured PCWP (r = 0.84, P < 0.0001) in the prospective group. The mean difference between the measured and estimated PCWP was - 0.4 +/- 3.6 mmHg. In patients with acute myocardial infarction, E/FPV by color M-mode Doppler during early left ventricular filling provides a better estimate of PCWP than transmitral or pulmonary venous flow.     

Relationship of pulmonary artery diastolic and pulmonary artery wedge pressures in mitral stenosis

Resting and exercise hemodynamic studies were performed in 33 patients with mitral stenosis (14 men and 19 women; average age, 25 years) in normal sinus rhythm with normal pulmonary vascular resistances. A normal pulmonary vascular resistance was assumed when the resting pressure gradient between the pulmonary artery diastolic and mean pulmonary artery wedge pressures was 5 mm. Hg or less. A satisfactory correlation existed between the pulmonary artery wedge and pulmonary artery diastolic pressures at rest (r = 0.9017) and during exercise (r = 0.8670). A method of predicting pulmonary artery wedge pressure from pulmonary artery diastolic pressure during exercise was formulated. The correlation between the predicted and measured exercise pulmonary artery wedge pressures was very close (r = 0.9561). It is suggested that during exercise the pulmonary artery diastolic pressure can be modified as above and substituted for mean pulmonary artery wedge pressure if the resting gradient between pulmonary artery wedge and pulmonary artery diastolic pressure is known.     

Pulmonary wedge angiography for the evaluation of the pulmonary vascular bed in congenital heart disease

Pulmonary wedge angiograms (PWA) were analyzed qualitatively and quantitatively to evaluate the pulmonary vascular bed in 40 patients with congenital heart disease. The patients were divided into four groups: group 1, normal pulmonary hemodynamics; group 2, increased pulmonary blood flow; group 3, pulmonary hypertension (PH); and group 4, PH with elevated pulmonary vascular resistance. The PWA were analyzed for tapering, pulmonary circulation time (PCT) index, and vascular image. The tapering was normal in groups 1 and 2 and was more rapid in groups 3 and 4. The PCT index was slightly lower in groups 3 and 4 than in groups 1 and 2. With 100% oxygen, the tapering became less severe and the PCT index increased in group 3. However in group 4, these parameters did not improve with 100% oxygen, suggesting that more advanced vascular changes had developed. These studies confirm the usefulness of the PWA in evaluating the pulmonary vascular bed of patients with congenital heart disease and PH.     

Left ventricular filling pattern and pulmonary wedge pressure are closely related in patients with recent anterior myocardial infarction and left ventricular dysfunction.

To determine whether mitral flow velocity can be used to estimate mean pulmonary wedge pressure (PWP) in patients with left ventricular dysfunction, 50 patients with recent Q-wave anterior infarction and a reduced ejection fraction (less than 40%) underwent simultaneous pulsed-wave Doppler measurements of mitral flow and right heart catheterization. Doppler tracings and PWP were recorded at rest, after passive leg lifting (45 degrees) and (in 15 patients with increased PWP) after 5 mg sublingual ISDN. Significant correlations were found between the ratio of peak early to peak late diastolic velocity (E/A) and PWP (r = 0.83). Early diastolic deceleration and the ratio of the time velocity integral of atrial contribution to the total time velocity integral were also correlated to PWP (r = 0.80 and r = 0.79 (respectively). The E/A ratio was less than 1 in 25 patients and more than 1 in the remaining 25. An E/A ratio of at least 1 predicted a PWP of more than 20 mmHg with a sensitivity of 100% and a specificity of 86%. In all five patients, in whom the PWP was less than 20 mmHg at baseline and became greater with leg lifting, the E/A ratio changed from less than 1 to more than 1. After ISDN, changes in E/A ratio from more than 1 to less than 1 identified all 12 patients with a PWP falling below 20 mmHg. In conclusion, patients with recent Q-wave anterior infarction and a reduced ejection fraction mitral flow velocity-derived variables correlate with PWP representing a reliable index for the diagnosis of markedly increased PWP.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical implication of inadvertent monitoring of pulmonary artery pressure via a “left atrial” catheter

A patient is described in whom a left atrial catheter was inadvertently wedged in a pulmonary vein following mitral valve replacement. The pulmonary vein wedge pressure obtained approximated the pulmonary artery pressure and was suggestive of paraprosthetic mitral valve regurgitation.     

What is the most appropriate variable for estimation of mean pulmonary capillary wedge pressure by transesophageal pulsed Doppler echocardiography?

Although left ventricular (LV) inflow and pulmonary venous (PV) flow variables estimated by transesophageal Doppler echocardiography (TEE) reflect pulmonary capillary wedge pressure (PCWP), they are also affected by changes in cardiac function. The purpose of the present study was to detect the most appropriate variable for the estimation of PCWP by TEE in patients (pts) with ischemic heart disease. Several variables of LV inflow and left upper PV flow were compared with PCWP in 36 pts (six with angina pectoris and 30 with old myocardial infarction). Early diastolic flow (E) and atrial contraction flow (A) were used as LV inflow, while systolic forward flow (X), diastolic forward flow (Y) and atrial contractile reversal flow (z) were used as PV flow. The peak velocity of each flow wave (Ep, Ap, Xp, Yp, and Zp) and the time-velocity integral (Ei, Ai, Xi, Yi, and Zi) were measured. The ratio of Ep to Ap (Ep/Ap), Ei to Ai (Ei/Ai), Xp to Yp (Xp/Yp), Xi to Yi (Xi/Yi), Zp to Ap (Zp/Ap), Zi to Ai (Zi/Ai) and the systolic fraction of PV forward flow were calculated. Among these variables, the Zi/Ai ratio was most strongly correlated with PCWP (R=0.80). The Zi/Ai ratio may not be influeced by atrial function because the augmentation of atrial pump function increases Zi as well as Ai, and this may be one reason why the ratio correlated well with PCWP.Conclusion: The Zi/Ai ratio is a new useful variable for estimating PCWP by TEE.Abbreviations Ap peak velocity of left ventricular inflow during atrial contraction - Ep peak velocity of left ventricular inflow during early diastole - Yp peak velocity of diastolic pulmonary venous forward flow - Xp peak velocity of systolic pulmonary venous forward flow - Zp peak velocity of pulmonary venous reversal flow during atrial contraction - Ai time-velocity integral of left ventricular inflow during atrial contraction - Ei timevelocity integral of left ventricular inflow during early diastole - Yi time-velocity integral of diastolic pulmonary venous forward flow - Zi time-velocity integral of pulmonary venous reversal flow during atrial contraction - Xi time-velocity integral of systolic pulmonary venous forward flow     

Non-invasive monitoring of pulmonary capillary wedge pressure in heart failure

OBJECTIVE: To evaluate the usefulness of pulsed Doppler (PD) mitral flow E wave deceleration time (EDcT) to detect and quantify changes of pulmonary capillary wedge pressure (PCWP) in patients (pt) with dilated chronic heart failure (CHF) submitted to tailored therapy. METHODS: In 14 pt with dilated cardiomyopathy (DCM) (59.4+/-10.0 years, 11 males, sinus rhythm), admitted to the ICU because of worsening CHF, serial simultaneous hemodynamic and echocardiographic studies were performed (3-5/pt; overall 49 evaluations). PD mitral flow register was used to measure EDcT and correlated with PCWP at each study. RESULTS: PCWP ranged from 36 to 3 mmHg (17.6+/-8.8) and EDcT from 271 to 52 ms (104.9+/-42.4). The correlation between EDcT and PCWP was -0.65 (PCWP=31.7-0.134EDcT). Using this equation to calculate PCWP, individual absolute values difference (identity error - IE) was 5.6+/-3.5 mmHg (0.4-14.6). In 29 cases (59.2%) IE was >5 mmHg, defined as major error. Considering EDcT percent change (delta%EDcT) and PCWP variation (deltaPCWP) in serial evaluations, we found a correlation of -0.87 (deltaPCWP=-2.83-0.19 delta%EDcT). Using this equation, the IE was 2.3+/-1.6 mmHg (0-5.2) and there were only two (6%) major errors (P<0.0001). CONCLUSIONS: In pt with DCM and advanced CHF, EDcT shows a reasonable correlation with PCWP, but when it is used to calculate PCWP the IE to hemodynamic values is often large. However, our results with EDcT percent change in serial evaluations using a first simultaneous invasive determination, suggest that this technique is reliable for monitoring PCWP and can be particularly useful for pt submitted to tailored therapy.     

A simple Doppler echocardiography method to evaluate pulmonary capillary wedge pressure in patients with atrial fibrillation

OBJECTIVE: The accuracy of E/E' ratio has not been validated in atrial fibrillation (AF). The objective of this study is to compare the accuracy of the E/E' ratio averaged over a sample of 10 cardiac cycles and E/E' ratio obtained in the cycle with the longest RR interval for the estimation of wedge pressure in patients with AF using a simultaneous pulmonary artery occlusive pressure measured with a Swan-Ganz catheter. DESIGN: Twenty-four consecutive patients with AF with a Swan-Ganz catheter were recruited in this study. The majority of patients (92%) were in the early postoperative phase of cardiac surgery. RESULTS: The best sensitivity and specificity was reached with E/E' ratio in the medial position using the one-beat method; E/E' ratio > or = 16 with one beat predicts a wedge pressure >15 mmHg with a sensitivity and specificity of 91% and 85%, respectively. CONCLUSIONS: Measuring E/E' ratio using the one-beat method is a simple and clinically accurate way to estimate wedge pressure in patients with AF.