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STUDY OBJECTIVE: The aim was to examine whether mid-systolic deceleration of the pulmonary flow wave occurred in acute pulmonary hypertension due to pulmonary artery constriction and pulmonary embolisation, and if so whether it was related to reflection. DESIGN: Various degrees of pulmonary hypertension were induced by both pulmonary artery constriction and pulmonary embolisation in dogs. During control periods and during pulmonary artery constriction and pulmonary embolisation, pulmonary flow and pulmonary artery pressure were recorded, and the forward and backward (reflected) flow waves were separated from the measured pulmonary flow wave by the method of Westerhof et al. MATERIALS: 20 adult mongrel dogs were used and 10 dogs qualified for analysis. The other 10 dogs, which died before both interventions were completed, were excluded. MEASUREMENTS AND MAIN RESULTS: During pulmonary artery constriction, a distinct mid-systolic deceleration of the pulmonary flow wave was observed in five of the 10 dogs, while during pulmonary embolisation, no mid-systolic deceleration was found in these five dogs. The distinct deceleration of the pulmonary flow wave was related to a steep fall and early negative peak in the backward flow wave. CONCLUSION: Mid-systolic deceleration of pulmonary flow wave is likely to be related to reflection.
BACKGROUND: Respiratory failure due to lung immaturity is a major cause of mortality in preterm infants. Although intermittent positive pressure ventilation (IPPV) saves lives, lung distortion during its use is associated with lung injury and chronic lung disease (CLD). Conventional IPPV is provided at 30-80 breaths per minute while a newer form of ventilation called high frequency oscillatory ventilation (HFOV) provides 'breaths' at 10-15 seconds. This has been shown to result in less lung injury in experimental studies. OBJECTIVES: The objective of this review is to determine whether the elective use of high frequency oscillatory ventilation (HFOV) as compared to conventional ventilation in preterm infants who are mechanically ventilated for the respiratory distress syndrome decreases the incidence of chronic lung disease (CLD) without adverse effects. SEARCH STRATEGY: Searches were made of the Oxford Database of Perinatal Trials, MEDLINE, EMBASE, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, journal handsearching by the Cochrane Collaboration, mainly in the English language. Expert informant's search in the Japanese language was made by Prof. Y. Ogawa. SELECTION CRITERIA: Randomized controlled trials comparing HFOV and CV in preterm or low birth weight infants with pulmonary dysfunction, mainly due to RDS, who are to be given IPPV. Randomization and commencement of treatment should have been as soon as possible after the start of IPPV and usually in the first 12 hours of life. DATA COLLECTION AND ANALYSIS: The methodological quality of each trial was independently reviewed by the various authors. Each author extracted data separately; they were compared and differences were resolved. The standard method of the Cochrane Neonatal Review Group was used to synthesize the data using relative risk (RR) and risk difference (RD). From 1/RD the number needed to treat (NNT) for benefits, and number needed to harm (NNH) for adverse effects, were calculated. MAIN RESULTS: Meta-analysis of the six eligible studies comparing HFOV with CV revealed that there is no difference in mortality. There are trends toward decreases in CLD in survivors at 28-30 days, 'death or CLD at 28-30 days' and CLD in survivors at 36-37 weeks postmenstrual age or discharge in the HFOV group. However, there are trends towards increases in severe (grades 3 & 4) intraventricular hemorrhage (IVH) and in periventricular leukomalacia (PVL) in the HFOV group. HFOV results in a small increase in any air leak syndrome (ALS), [summary RR 1.20 (1.03, 1.39)]. Only 2 trials have included neurodevelopmental follow up and more survivors in the HFOV group are abnormal [summary RR 1.26 (1.01, 1.58)]. In the subgroup of four trials where a high volume strategy (HVS) was used, HFOV results in more favourable pulmonary outcomes. There are significantly lower rates of CLD in survivors at 28-30 days [summary RR 0.53 (0.36, 0.76)] and of 'death or CLD at 28-30 days' [summary RR 0.56 (0.40, 0.77) with a non-significant trend towards a reduction in oxygen use at 36-37 weeks postmenstrual age or discharge [summary RR 0.74 (0.55, 1.01)]. There were no differences in the rates of IVH or PVL. Of the four trials in the subgroup using surfactant routinely, three also used the HVS. The trends in results were similar with surfactant to those for the HVS subgroup analysis. One trial suggests that HFOV may reduce the cost of in-hospital care. In the subgroup of two trials (HIFI 1989, Rettwitz-Volk 1998) not using a HVS there is no effect of HFOV on the rate of CLD; however, there is an increase in the rate of PVL [summary RR 1.64 (1.02, 2.64). REVIEWER'S CONCLUSIONS: The overall meta-analyses is dominated by the large HIFI study which did not use the HVS recommended on the basis of animal studies, and in which surfactant was not available. Studies which used HVS have shown some benefits in short term measures of CLD without an in
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A patient with the rare combination of tetralogy of Fallot with severe pulmonary valvar stenosis and pulmonary vascular sling is presented. The limitations imposed by pulmonary artery hypoplasia on the display of pulmonary vascular sling by conventional imaging techniques are discussed.
A new selection criterion for Fontan procedure, pulmonary artery clamping test (PACT) was developed and employed in 13 candidates for Fontan procedure. PACT was aimed to evaluate the response of pulmonary vascular bed to increased pulmonary blood flow and calculate the pulmonary vascular resistance in the increased pulmonary blood flow as a selection criterion for Fontan procedure, preoperatively. After a median sternotomy incision, an electromagnetic flow meter was employed for measuring the pulmonary blood flow (Qp) on the pulmonary trunk. By clamping the left pulmonary artery and the right pulmonary artery, right pulmonary vascular resistance and the left pulmonary resistance in the pulmonary blood flow of Qp were calculated respectively. By means of electrical analogue, right and left lungs were simulated as resistors in parallel. And the equivalent pulmonary vascular resistance Rpc was calculated as the predicted pulmonary vascular resistance in the increased pulmonary blood flow of two times Qp. Fontan procedure was performed in 9 cases with a Rpc of less than 3 unit.m2 with a successful result and no death. Postoperative cardiac index ranged from 2.6 to 3.7 L/min.m2 with a mean of 2.8 L/min.m2. Postoperative pulmonary vascular resistance ranged from 1.6 to 3.2 unit.m2. Postoperative cardiac index was correlated with postoperative pulmonary vascular resistance. And postoperative pulmonary vascular resistance was well correlated with equivalent pulmonary vascular resistance but was not correlated with preoperative pulmonary vascular resistance measured by Fick's method at the preoperative catheterization. In Fontan procedure, the pulmonary blood flow frequently increases to a certain degree postoperatively. And pulmonary vascular resistance is not a static resistance, but a dynamic resistance. Hence, in discussing a pulmonary vascular resistance as a selection criterion for Fontan procedure, the pulmonary blood flow in which the pulmonary vascular resistance stand should be taken into account. Equivalent pulmonary vascular resistance Qpc is a theoretical selection criterion for Fontan procedure and well reflects the postoperative pulmonary vascular resistance. Fontan procedure can be successfully performed with a Rpc of less than 3 unit.m2.
OBJECTIVE: Preoperative pulmonary venous obstruction has been reported to be a risk factor negatively impacting survival in total anomalous pulmonary venous connection. We examined lung tissue from total anomalous pulmonary venous connection patients with pulmonary venous obstruction and demonstrated hypoplasia of small pulmonary arteries to elucidate the mechanism underlying the poor outcome. METHODS: Ten total anomalous pulmonary venous connection patients with preoperative pulmonary venous obstruction between the ages of 2 days and 10 months were studied. As histological parameters, we assessed the size of small pulmonary arteries in relation to the size of accompanying bronchioles to identify small pulmonary artery underdevelopment. Other parameters, such as the radial alveolar count, which reflects alveolar maturity, intimal lesions, lymphangiectasia, and the medial thickness of small pulmonary arteries and small pulmonary veins, were also examined. As a control group, we examined 24 autopsy cases with no congenital heart or pulmonary disease. RESULTS: When the radius of the accompanying bronchiole was 100 microm, the radius of small pulmonary artery in the control group was found to enlarge for the first 2 months and then remain stable at approximately 80 microm from 2 to 10 months. In total anomalous pulmonary venous connection with preoperative pulmonary venous obstruction, the radius was significantly lower than in the control (47.0 +/- 21.8 microm versus 75.9 +/- 9.8 microm, P <.001), and the difference between dead and surviving patients was significant at P <.001 (33.0 +/- 14.6 microm versus 68.2 +/- 9.2 microm). Examination of the alveoli yielded an radial alveolar count of 4.6 +/- 1.5 in the control group and 4.4 +/- 0.8 in the total anomalous pulmonary venous connection patients, and the difference was not significant (P =.71). CONCLUSIONS: The small pulmonary arteries of total anomalous pulmonary venous connection patients with preoperative pulmonary venous obstruction were underdeveloped compared with controls but their alveolae were not hypoplastic. These results suggested that the small pulmonary artery hypoplasia may be responsible for the poor outcome of these patients.
To evaluate pulmonary vasodilation in a structurally altered pulmonary vascular bed, we gave endothelium-dependent (acetylcholine) and endothelium-independent [sodium nitroprusside, prostaglandin I2 (PGI2)] vasodilators in vivo and to isolated lobar pulmonary arteries from neonatal calves with severe pulmonary hypertension. Acetylcholine, administered by pulmonary artery infusion, decreased pulmonary arterial pressure from 120 +/- 7 to 71 +/- 6 mmHg and total pulmonary resistance from 29.4 +/- 2.6 to 10.4 +/- 0.9 mmHg.l-1.min without changing systemic arterial pressure (90 +/- 5 mmHg). Although both sodium nitroprusside and PGI2 lowered pulmonary arterial pressure to 86 +/- 4 and 96 +/- 4 mmHg, respectively, they also decreased systemic arterial pressure to 65 +/- 4 and 74 +/- 3 mmHg, respectively. Neither sodium nitroprusside nor PGI2 was as effective as acetylcholine at lowering total pulmonary resistance (18.0 +/- 3.6 and 19.1 +/- 2.2 mmHg.l-1.min, respectively). Right-to-left cardiac shunt through the foramen ovale was decreased by acetylcholine from 1.6 +/- 0.4 to 0.1 +/- 0.2 l/min but was not changed by sodium nitroprusside or PGI2. Isolated lobar pulmonary arteries from pulmonary hypertensive calves did not relax in response to acetylcholine, whereas isolated pulmonary arteries from age-matched control calves did relax in response to acetylcholine. Control and pulmonary hypertensive lobar pulmonary arteries relaxed equally well in response to sodium nitroprusside. We concluded that acetylcholine vasodilation was impaired in vitro in isolated lobar pulmonary arteries but was enhanced in vivo in resistance pulmonary arteries in neonatal calves with pulmonary hypertension.
An angiographic and clinical study was performed to establish the prevalence of juxtaductal pulmonary artery coarctations in patients with pulmonary atresia or stenosis and a ventricular septal defect or a complex intracardiac defect. The present study is an adjunct to a previously reported portmortem study, in which the incidence of these pulmonary artery coarctations was found to be unexpectedly high. Pulmonary artery coarctations were identified angiographically in 10 of the 15 patients with pulmonary atresia. One additional patient had a bilateral ductus arteriosus and confluent pulmonary arteries, but did not have a pulmonary artery coarctation. Pulmonary artery coarctations were much less prevalent in the cases with pulmonary stenosis (5/50). However, these pulmonary artery coarctations appeared identical to those of the cases with pulmonary atresia. Fourteen pulmonary artery coarctations were located in the pulmonary artery at the side of the ductus arteriosus; this was left sided in 12 and right sided in two patients. In one patient the side of the ductus could not be established. The types and the locations of the pulmonary artery coarctations in the present study were identical to those in the previous postmortem study. Ductal tissue was found in many of the pulmonary artery coarctations of the postmortem study and is likely to be present in the clinical cases as well. The majority of the angiographically identified pulmonary artery coarctations were subsequently confirmed at operation or at autopsy. The clinical outcome and follow-up of the patients is discussed, and it is concluded that juxtaductal pulmonary artery coarctations should be specifically looked for before and during any type of surgical intervention in these patients.
OBJECTIVES: This study sought to determine the results of a novel transcatheter management approach in tetralogy of Fallot with diminutive pulmonary arteries. BACKGROUND: Tetralogy of Fallot with diminutive pulmonary arteries and severe pulmonary stenosis is rare and resembles tetralogy of Fallot with pulmonary atresia: There is a high incidence of aortopulmonary collateral channels, arborization abnormalities, stenoses and need for multiple operations. Because a combined catheter-surgery approach facilitates repair in these patients, such an approach may benefit those with diminutive pulmonary arteries and pulmonary stenosis. METHODS: Clinical, catheterization and surgical data were studied retrospectively for 10 such patients undergoing preoperative pulmonary valve balloon dilation, among other transcatheter interventions, from January 1989 to January 1995. RESULTS: Initially, the Nakata index ranged from 20 to 98 mm2/m2 (mean 67 +/- 28 mm2/m2). The pulmonary valve was first balloon dilated (mean balloon/annulus 1.5 +/- 0.3), and the mean initial valve annulus Z score (-4.0 +/- 1) increased to -33 +/- 1.1 (p < 0.01) Other interventions included branch pulmonary artery balloon dilation (7 patients, 23 vessels) and coil embolization of aortopulmonary collateral channels (8 patients, 31 collateral channels). At preoperative follow-up catheterization, the mean pulmonary annulus Z score was -3.1 +/- 0.7, and the Nakata index increased to 143 +/- 84 mm2/m2 (p < 0.03). All patients underwent complete surgical repair successfully. At a mean follow-up period of 2.6 +/- 2 years, right ventricular pressure was < 70% systemic in all patients and < 50% systemic in seven. CONCLUSIONS: In patients with tetralogy of Fallot, severe pulmonary stenosis and diminutive pulmonary arteries, initial pulmonary valve balloon dilation increases the annulus Z score and anterograde pulmonary blood flow and facilities simultaneous coiling of aortopulmonary collateral channels and access for branch pulmonary artery dilation, all of which results in pulmonary artery growth, simplifying surgical management.
OBJECTIVE: This study was undertaken to compare the accuracy of echocardiography versus pulmonary artery catheterization to estimate pulmonary artery pressures in pregnant women with suspected pulmonary hypertension. STUDY DESIGN: A retrospective chart review was performed between January 1990 and February 2000 for all pregnant patients with cardiac disease. Patients with pulmonary artery pressure values estimated by cardiac catheterization and echocardiography during pregnancy were included. Pulmonary hypertension is defined as pulmonary artery systolic pressure >30 mm Hg. RESULTS: Twenty-seven patients were included in the study. There was a significant overestimation of the mean pulmonary artery pressure with echocardiography compared with catheterization (55.4 vs 51.1 mm Hg; P <.005). Of the 20 patients, pulmonary artery pressure was significantly greater when estimated by echocardiography than when measured by catheterization (59.6 vs 54.8 mm Hg; P <.004). Thirty-two percent (8/25) of the patients had pulmonary hypertension when estimated by echocardiography but had normal pulmonary artery pressures on subsequent catheterization. CONCLUSION: Echocardiography significantly overestimated pulmonary artery pressures compared with catheterization in pregnant patients with suspected pulmonary hypertension. Patients with structural cardiac defects appear to have a significantly greater difference in pulmonary artery pressures. Thirty-two percent of pregnant patients with normal pulmonary artery pressures may be misclassified as having pulmonary artery hypertension when measured by echocardiography alone.
We evaluated in patients suffering from COPD-related pulmonary hypertension whether nifedipine therapy lowers acutely and chronically pulmonary vascular pressure and resistance and whether pulmonary transmural pressure may be further lowered by the combined use of nifedipine and oxygen. Changes of the pulmonary vascular tone were determined on the pulmonary driving pressure/flow curve, which was generated by upright exercise. Fifteen patients with COPD and mean pulmonary pressure greater than or equal to 20 mm Hg were studied at control (Week 0) and after 1 wk of nifedipine treatment (180 mg daily, Week 1). It was possible to pursue the same nifedipine daily dosage for 2 months in 10 patients, who were re-evaluated after 8 wk of treatment and after nifedipine withdrawal the following week. At Week 1, mean pulmonary transmural pressure was reduced (32.8 +/- 4.1 versus 27.3 +/- 2.8 mm Hg, mean +/- SE, p less than 0.05) via active pulmonary vasodilation because the pulmonary driving pressure/flow curve was shifted right and downward. Both mean transmural pulmonary pressure lowering effect and active pulmonary vasodilatation regressed during long-term nifedipine treatment. Oxygen reduced pulmonary transmural pressure (32.8 +/- 4.1 versus 28.6 +/- 2.9 mm Hg, p less than 0.05, Week 0); however, this effect always disappeared during nifedipine treatment. We conclude that nifedipine should not be used as long-term treatment for COPD-related pulmonary hypertension and that nifedipine inhibits the oxygen capability to reduce pulmonary pressure.
Chronic pulmonary hypertension in humans is characterized by shortening of the pulmonary artery acceleration time as measured by Doppler echocardiography, such that the higher the pulmonary artery pressure, the shorter the pulmonary acceleration time. Increases in heart rate are also known to produce decreases in the pulmonary artery acceleration time. To explore the relationship between mean pulmonary artery pressure, heart rate, and Doppler pulmonary artery acceleration time, experimental acute pulmonary hypertension was created in nine Duroc swine, either by infusion of Sephadex beads with embolization of the pulmonary arterial circulation or by partially occluding the main pulmonary artery 8 to 10 cm distal to the pulmonic valve. Pulmonary artery Doppler flow velocity recordings and invasive pressure measurements were made at baseline and at paced atrial rates ranging from 60 to 160 beats per minute, in 20-beat increments. The results in this acute animal model reveal that increases in heart rate produced significant decreases in Doppler pulmonary artery acceleration time at mean pressures below 25 mm Hg. However, with mean pulmonary artery pressures greater than 25 mm Hg, both heart rate and increases in pulmonary artery pressure had no significant effect on acceleration time.
OBJECTIVE: To compare the function in aortic position of cryopreserved pulmonary homografts subjected to pulmonary hypertension with that of normal cryopreserved pulmonary homografts. METHODS: Pulmonary valves (52) were implanted in aortic position in different cardiothoracic centres. The valves were classified as follows: Group I-pulmonary hypertension (procured from recipients of heart/heart-lung transplantation, 31 valves), Group II-normal pulmonary pressure (procured from cadavers and multiorgan donors, 21 valves). Regular echocardiographic follow-up was obtained by the implanting centers. Significant echo changes were defined as insufficiency > 2+ and/or stenosis producing a delta P > 30 mm Hg. RESULTS: Pulmonary homografts showed the following significant echo changes: in the Pulmonary Hypertension Group, 7, 27 and 33% at 12, 24 and 36 months, respectively; in the normal PA Group 10, 37.5 and 80% at 12, 24 and 36 months, respectively. In both groups the most common echocardiographic alteration was homograft insufficiency rather than stenosis. Thus, pulmonary homografts subjected to long-term pulmonary hypertension have significantly less echo changes than normal pulmonary homografts, especially after 12 months (chi 2: P < 0.036). CONCLUSIONS: These findings suggest that pulmonary valves subjected to pulmonary hypertension might be more appropriate than normal pulmonary homograft for aortic valve replacement, constituting a possible alternative in case of lack of aortic valve homografts. However, the failure of two out of five valves in the longer term must dictate caution while waiting further long-term results.
High retrograde pressure through the pulmonary venous system caused by failure of the left ventricle or left atrio-ventricular valve may result in the elevated pulmonary arterial pressure and right ventricular hypertrophy associated with pulmonary hypertension syndrome (PHS; ascites) in broiler chickens. In the present study, unanaesthetized male broilers from an ascites-resistant line, the base population from which the resistant line was derived, and a separate unselected line were used to determine whether changes in wedge pressure (thought to be similar to left atrial pressure) are predictive of differences in the pulmonary arterial pressure of clinically healthy and pre-ascitic broilers. Venous, right atrial, right ventricular, pulmonary arterial, and wedge pressures were obtained by inserting a catheter into a wing vein and progressively advancing the catheter into a pulmonary branch artery until the catheter tip became wedged in and occluded the flow through a terminal artery. Mean right ventricular and pulmonary arterial pressures were lower in the resistant line than in the base population, but wedge pressures did not differ between the resistant, base, and unselected lines. Right:total ventricular weight ratios (RV:TV) and the percentage saturation of hemoglobin with oxygen in arterial blood ranged in value from 0.18 to 0.44 and 65 to 96%, respectively. Wedge pressure, however, remained similar when pre-ascitic broilers with high RV:TV values and low oximetry values were compared with clinically healthy broilers. In all birds, whether healthy or showing pre-ascitic characteristics, the wedge pressure was slightly higher than the right atrial pressure but substantially lower than pulmonary arterial pressure. These observations provide definitive proof that pulmonary hypertension is initiated as a consequence of excessive pulmonary arterial or arteriole resistance. Pulmonary venous pressure is estimated by measuring the pulmonary arterial wedge pressure, and high wedge pressures would be evident if pulmonary hypertension was caused by the elevated downstream resistances associated with left-sided heart failure.
We performed this study to assess the correlation of residual pulmonary hypertension in the immediate postoperative period with that in the late follow-up period, to assess the histologic changes of pulmonary arteries (PA) at the time of repair for patients with congenital heart disease consisting of left-to-right shunt, and to clarify the role of lung biopsy in determining the operability and reversibility of pulmonary vascular changes. Lung biopsy was performed during repair in 38 patients, with a wide range of age, who had congenital left to right shunt and pulmonary hypertension. All were Heath-Edward grade III or less. Morphometric study included measurement of medial wall thickness (MWT) and decrease rate of pulmonary arterial concentration (PAC). Mean PA pressure in the immediate postoperative period was measured in all 38 patients. Follow-up cardiac catheterization was performed in 15 patients (average 3.8 years after repair). At operation, 5 patients of this late follow-up group were under 2 years of age and the other 10 were 2 or more. During catheterization, pulmonary hemodynamic reaction was observed both under room air inhalation and after inhalation of hypoxic gas FiO2 0.15. Mean PA pressure and pulmonary vascular resistance (PVR) in the immediate postoperative period had a significant correlation with PA pressure and PVR values before the operation, but not with morphometry, Heath-Edward grade, or with pulmonary hemodynamics in late follow-up. During the late follow-up study, 5 of the 15 patients had pulmonary hypertension (defined as mean PA pressure > or = 15 mmHg) under room air inhalation, and PA hypertension was induced in 4 additional patients after hypoxic gas inhalation. There was no incidence of PA pressure or PVR values registering above the preoperative level. The degree of PA hypertension showed a correlation with the rate of PAC decrease and also with patients' age-at-operation. Multiple regression analysis showed that both the rate of PAC decrease and the age-at-operation contributed significantly to the degree of PA hypertension. Some of the patients over age 2 had a decreased rate of PAC above the regression line, which none of the patients under age 2 experienced. In patients with Heath-Edward grade III or less, residual pulmonary hypertension in the immediate postoperative period was not correlated with histology, but in late follow-up, it was with PAC and the age-at-operation. Therefore, a decrease of PAC is assumed to be a totally or partially irreversible pulmonary vascular change depending on the patient's age-at-operation, while medial hypertrophy is thought to be a reversible pulmonary vascular change. Lung biopsy could play an important role in determining the reversibility of pulmonary vascular obstruction, particularly in patients older than 2 years. Ed- re highlights above: such hyphenation is optional, but if used then it should be applied consistently throughout the paper. As 3 of the 4 entries in the abstract use it, I have maintained it consistently below.
Qualitative and quantitative studies were performed on pulmonary blood vessels in lung tissue obtained by biopsy, pneumonectomy, or autopsy from 58 patients in the Registry of Primary Pulmonary Hypertension sponsored by the Heart, Lung, and Blood Institute of the National Institutes of Health. In 49 patients (84%), the hypertensive vascular disease involved predominantly or exclusively muscular pulmonary arteries and arterioles. In each of these 49 patients, pulmonary artery medial hypertrophy was observed, and in 48 patients, it was also associated with intimal or luminal lesions. On the basis of the predominant histopathologic features, 25 of the 48 patients were classified as having pulmonary arteriopathy with plexiform lesions characterized by a combination of concentric laminar intimal fibrosis, eccentric intimal fibrosis, and plexiform lesions; in nine of these 25, recanalized thrombi were also present. Pulmonary arteriopathy with thrombotic lesions, defined by the presence of both eccentric intimal fibrosis and recanalized thrombi but without plexiform lesions, was observed in 19 patients. Intimal fibrosis, either concentric or eccentric, without plexiform or thrombotic lesions was found in four patients. Among the remaining nine patients in the Registry, pulmonary veno-occlusive disease was present in seven and chronic pulmonary venous hypertension in one. Pulmonary blood vessels were microscopically normal in a lung biopsy specimen from another patient. In general, patients with plexiform lesions and those with veno-occlusive disease had a much poorer prognosis than patients with thrombotic lesions. The present study shows the existence of several distinct histopathologic patterns of pulmonary vascular disease in individuals with primary pulmonary hypertension diagnosed by standardized clinical and laboratory criteria.
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.