Open lung biopsies in congenital heart disease for evaluation of pulmonary vascular disease. Predictive value with regard to corrective operability

Pulmonary artery pressure-directed therapies in pulmonary arterial hypertension?

Pulmonary arterial hypertension is a rare dyspnea-fatigue syndrome defined by an increase in mean pulmonary artery pressure above 20 mmHg combined with an increase in pulmonary vascular resistance higher than 2 Wood units. The condition is of poor prognosis and still incurable in spite of progress achieved in recent decades. The approach is currently optimized by multi-drug combinations titrated on serial risk assessments using recently validated scores. In this issue of Vascular Pharmacology argument is made based on retrospective registry data from three reference centers in favor of initial multi-drug therapies including a parenteral prostanoid dosed to decrease mPAP to normal. This objective was achieved in only a minority of patients, but improved outcome was demonstrated when mPAP can be brought to below 35 mmHg. This data suggest that pulmonary artery pressure-directed multi-drug therapies in PAH may reverse right heart remodeling and limit progression, or even reverse pulmonary vascular disease. However, further studies are needed to validate mPAP as a primary endpoint in PAH drug trials. In the meantime, aggressive initial prescription of parenteral prostanoids combined with one or two oral drugs targeting the pulmonary circulation under careful clinical, imaging and hemodynamic follow-up may be the best therapeutic strategy.

Cellular senescence impairs the reversibility of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) in congenital cardiac shunts can be reversed by hemodynamic unloading (HU) through shunt closure. However, this reversibility potential is lost beyond a certain point in time. The reason why PAH becomes irreversible is unknown. In this study, we used MCT+shunt-induced PAH in rats to identify a dichotomous reversibility response to HU, similar to the human situation. We compared vascular profiles of reversible and irreversible PAH using RNA sequencing. Cumulatively, we report that loss of reversibility is associated with a switch from a proliferative to a senescent vascular phenotype and confirmed markers of senescence in human PAH-CHD tissue. In vitro, we showed that human pulmonary endothelial cells of patients with PAH are more vulnerable to senescence than controls in response to shear stress and confirmed that the senolytic ABT263 induces apoptosis in senescent, but not in normal, endothelial cells. To support the concept that vascular cell senescence is causal to the irreversible nature of end-stage PAH, we targeted senescence using ABT263 and induced reversal of the hemodynamic and structural changes associated with severe PAH refractory to HU. The factors that drive the transition from a reversible to irreversible pulmonary vascular phenotype could also explain the irreversible nature of other PAH etiologies and provide new leads for pharmacological reversal of end-stage PAH.

Vital Roles of Gremlin-1 in Pulmonary Arterial Hypertension Induced by Systemic-to-Pulmonary Shunts

Background Heterozygous mutation in BMP (bone morphogenetic protein) receptor 2 is rare, but BMP cascade suppression is common in congenital heart disease-associated pulmonary arterial hypertension (CHD-PAH); however, the underling mechanism of BMP cascade suppression independent of BMP receptor 2 mutation is unknown. Methods and Results Pulmonary hypertensive status observed in CHD-PAH was surgically reproduced in rats. Gremlin-1 expression was increased, but BMP cascade was suppressed, in lungs from CHD-PAH patients and shunted rats, whereas shunt correction retarded these trends in rats. Immunostaining demonstrated increased gremlin-1 was mainly in the endothelium and media of remodeled pulmonary arteries. However, mechanical stretch time- and amplitude-dependently stimulated gremlin-1 secretion and suppressed BMP cascade in distal pulmonary arterial smooth muscle cells from healthy rats. Under static condition, gremlin-1 significantly promoted the proliferation and inhibited the apoptosis of distal pulmonary arterial smooth muscle cells from healthy rats via BMP cascade. Furthermore, plasma gremlin-1 closely correlated with hemodynamic parameters in CHD-PAH patients and shunted rats. Conclusions Serving as an endogenous antagonist of BMP cascade, the increase of gremlin-1 in CHD-PAH may present a reasonable mechanism explanation for BMP cascade suppression independent of BMP receptor 2 mutation.

Remodeling Matrix Synthesis in a Rat Model of Aortocaval Fistula and the Cyclic Stretch: Impaction in Pulmonary Arterial Hypertension-Congenital Heart Disease

Pulmonary arterial hypertension-congenital heart disease (PAH-CHD) is characterized by systemic to pulmonary arterial shunts and sensitively responds to volume overload and stretch of the vascular wall leading to pulmonary vascular remodeling. We hypothesized that the responses of pulmonary artery smooth muscle cells (PASMCs) to mechanical stress-associated volume overload may promote vascular remodeling in PAH-CHD. Here, we show that significantly increased collagen was in the PA adventitial layer by trichrome staining in PAH-CHD patients and an aortocaval fistula (ACF) rat model in which chronic vascular volume overload induced-PAH. We assessed the gene expression profiles of SMC markers, extracellular matrix, and collagen in isolated SMCs from pulmonary and thoracic vessels with cyclic stretch-triggered responses by real-time PCR analysis. The data corresponded to collagen deposition, which modulated pulmonary vascular remodeling in clinical and experimental PAH-ACF cases as well as in cyclic stretch-triggered SMCs in an in vitro model. We observe that collagen I A2 (COLIA2) is expressed in the control rat, but collagen I A1 (COLIA1) and Notchs remarkably increase in the lungs of ACF rats. Interestingly, closing the left-to-right shunt that leads to a reduced blood volume in the PA system of ACF rats (ACFRs) decreased the expression of COLIA1 and increased that of collagen I A2(COLIA2). This study contributes to the stretch-induced responses of SMCs and provides important future directions for therapies aimed at preventing abnormal matrix protein synthesis in volume overload-induced pulmonary hypertension (PH).

"Treat and repair" strategy for shunt lesions: a critical review

The issue of operability in patients with shunt lesions and raised pulmonary vascular resistance is contentious. Several reports suggest that patients traditionally considered inoperable may be operated after treatment with targeted drug therapy for pulmonary arterial hypertension. We reviewed all the published literature of "treat and repair" approach to gain more insights into the utility of this approach. A critical appraisal of the published literature suggests that this approach is less established for patients with post tricuspid shunts, and for patients with pre-tricuspid shunts with modestly elevated indexed pulmonary vascular resistance (possibly greater than 11 WU.m²). Targeted drug therapy may be able to extend the therapeutic window in carefully selected patients, but its use as a routine in this setting seems unwarranted.

Osteopontin plays important roles in pulmonary arterial hypertension induced by systemic-to-pulmonary shunt

Recent studies indicated that osteopontin (OPN) was involved in the genesis and progression of pulmonary arterial hypertension (PAH); however, its role in congenital heart disease-associated PAH (CHD/PAH) remains unknown. Our results showed that OPN was increased in lungs and plasma of patients with Eisenmenger syndrome; moreover, OPN and α_Vβ₃-integrin expression levels were augmented in rat lungs exposed to systemic-to-pulmonary shunt. Cell culture assay demonstrated that distal pulmonary arterial smooth muscle cells (PASMCs) from rat lungs suffering from volume and pressure overload exhibited enhanced proliferation compared with those from healthy rats. Mechanical stretch (20% at 1 Hz) increased OPN expression and activated ERK1/2 and protein kinase B (Akt) signal pathway in distal PASMCs from healthy rats. Interestingly, OPN enhanced the proliferation and migration of PASMCs while blocking α_Vβ₃-integrin with neutralizing antibody LM609 or Arg-Gly-Asp peptidomimetic antagonist cyclo(Ala-Arg-Gly-Asp-3-aminomethylbenzoyl) (XJ735), rectified the proliferative and migratory effects of OPN, which were partially mediated via ERK1/2 and Akt signaling pathways. Furthermore, surgical correction of systemic-to-pulmonary shunt, particularly XJ735 supplementation after surgical correction of systemic-to-pulmonary shunt, significantly alleviated the pulmonary hypertensive status in terms of pulmonary hemodynamic indices, pulmonary vasculopathy, and right ventricular hypertrophy. In summary, OPN alteration in lungs exposed to systemic-to-pulmonary shunt exerts a deteriorative role in pulmonary vascular remodeling through modulating the proliferation and migration of PASMCs, at least in part, via ανβ3-ERK1/2 and ανβ3-Akt signaling pathways. Antagonizing OPN receptor ανβ3-integrin accelerated the regression of pulmonary vasculopathy after surgical correction of systemic-to-pulmonary shunt, indicating a potential therapeutic strategy for patients with CHD/PAH.-Meng, L., Liu, X., Teng, X., Gu, H., Yuan, W., Meng, J., Li, J., Zheng, Z., Wei, Y., Hu, S. Osteopontin plays important roles in pulmonary arterial hypertension induced by systemic-to-pulmonary shunt.

Profound Increase of Lung Airway Resistance in Heart Failure: a Potential Important Contributor for Dyspnea

Dyspnea is a major symptom of heart failure (HF). Here, we have studied the lung remodeling and airway resistance in HF mice. We demonstrated that aortic banding-induced HF caused a dramatic decrease of lung compliance and an increase of lung airway resistance. The decrease of lung compliance was correlated with the increased lung weight in a linear fashion (γ² = 0.824). An HF-induced increase of lung airway resistance and a decrease of lung compliance were almost identical in anesthetized mice and in the isolated lungs from these mice. HF caused profound lung fibrosis in mice with increased lung weight. Moreover, HF patients of NYHA class III-IV showed increased lung density as revealed by high-resolution CT scanning. These data indicate that lung compliance and lung airway resistance may be useful in determining lung remodeling after HF, and lung structure changes may contribute to dyspnea in HF.

Assessment of reversibility in pulmonary arterial hypertension and congenital heart disease

Pulmonary arterial hypertension (PAH) in congenital heart disease (CHD) can be reversed by early shunt closure, but this potential is lost beyond a certain point of no return. Therefore, it is crucial to accurately assess the reversibility of this progressive pulmonary arteriopathy in an early stage. Reversibility assessment is currently based on a combination of clinical symptoms and haemodynamic variables such as pulmonary vascular resistance. These measures, however, are of limited predictive value and leave many patients in the grey zone. This review provides a concise overview of the mechanisms involved in flow-dependent progression of PAH in CHD and evaluates existing and future alternatives to more directly investigate the stage of the pulmonary arteriopathy. Structural quantification of the pulmonary arterial tree using fractal branching algorithms, functional imaging with intravascular ultrasound, nuclear imaging, putative new blood biomarkers, genetic testing and the potential for transcriptomic analysis of circulating endothelial cells and educated platelets are being reviewed.

Pulmonary arterial hypertension in congenital heart disease: translational opportunities to study the reversibility of pulmonary vascular disease

Pulmonary arterial hypertension (PAH) is a progressive and lethal pulmonary vascular disease (PVD). Although in recent years outcome has improved by new treatments that delay disease progression, a cure has not yet been achieved. In PAH associated with congenital heart disease (CHD), remodeling of the pulmonary vasculature reaches an irreversible phenotype similar to all forms of end-stage PAH. In PAH-CHD, however, also an early stage is recognised, which can be completely reversible. This reversible phase has never been recognised in other forms of PAH, most likely because these patients are only diagnosed once advanced disease has developed. We propose that the clinical model of PAH-CHD, with an early reversible and advanced irreversible stage, offers unique opportunities to study pathophysiological and molecular mechanisms that orchestrate the transition from reversible medial hypertrophy into irreversible plexiform lesions. Comprehension of these mechanisms is not only pivotal in clinical assessment of disease progression and operability of patients with PAH-CHD; specific targeting of these mechanisms may also lead to pharmacological interventions that transform 'irreversible' plexiform lesions into a reversible PVD: one that is amenable for a cure. In recent years, significant steps have been made in the strive to 'reverse the irreversible'. This review provides an overview of current clinical and experimental knowledge on the reversibility of PAH, focussing on flow-associated mechanisms, and the near-future potential to advance this field.

Prognostic significance of arterial and venous thrombosis in resected specimens for non-small cell lung cancer

BACKGROUND

Venous thromboembolism(VTE) is common after pneumonectomy for malignancy and predicts poor survival. Routine screening for VTE with noninvasive tests has low sensitivity and specificity. Biopsy of lung has a place in establishing the nature and severity of the vascular alterations. In this study, we investigated the incidence, clinical and pathological characteristics of thrombosis in excised specimens after pneumonectomy, and its association with survival rate in patients with non-small cell lung cancer (NSCLC).

METHODS

The studied population consisted 94 consecutive patients after pneumonectomy for NSCLC in Beijing Chao-Yang Hospital, The excised tissue specimens were stained by haematoxylin & eosin staining (HE) to observe thrombosis events. All the patients were followed up for 2years. The survival data was analyzed by Kaplan-Meier analysis.

RESULTS

Overall thrombosis events occurred in 56 (59.6%) of 94 NSCLC cases, pulmonary arterial thrombosis was found in 24 cases, and pulmonary venous thrombosis was found in 32 cases. Furthermore, 30 of 56 cases with thrombosis were accompanied by tumor emboli or tumor vascular infiltrating. Thrombosis risk was associated with cancer grade (P=0.005). Kaplan-Meier analysis showed that patients with thrombosis had lower survival rate than those without thrombosis (P=0.025).

CONCLUSIONS

The incidence of thrombosis in excised tissue after pneumonectomy was high in patients with NSCLC, and it may be a marker of poor outcome.

Pulmonary vascular disease related to hemodynamic stress in the pulmonary circulation

Hemodynamic stress in the pulmonary vessel is directly linked to the development of vascular remodeling and dysfunction, ultimately leading to pulmonary hypertension. Recently, some advances have been made in our molecular understanding of the exogenous upstream stimuli that initiate hemodynamic pertubations as well as the downstream vasoactive effectors that control these responses. However, much still remains unknown regarding how these complex signaling pathways connect in order to result in these characteristic pathophysiological changes. This chapter will describe our current understanding of and needed areas of research into the clinical, physiological, and molecular changes associated with pressure/volume overload in the pulmonary circulation.

Animal models of pulmonary arterial hypertension: the hope for etiological discovery and pharmacological cure

At present, six groups of chronic pulmonary hypertension (PH) are described. Among these, group 1 (and 1′) comprises a group of diverse diseases termed pulmonary arterial hypertension (PAH) that have several pathophysiological, histological, and prognostic features in common. PAH is a particularly severe and progressive form of PH that frequently leads to right heart failure and premature death. The diagnosis of PAH must include a series of defined clinical parameters, which extend beyond mere elevations in pulmonary arterial pressures and include precapillary PH, pulmonary hypertensive arteriopathy (usually with plexiform lesions), slow clinical onset (months or years), and a chronic time course (years) characterized by progressive deterioration. What appears to distinguish PAH from other forms of PH is the severity of the arteriopathy observed, the defining characteristic of which is “plexogenic arteriopathy.” The pathogenesis of this arteriopathy remains unclear despite intense investigation in a variety of animal model systems. The most commonly used animal models (“classic” models) are rodents exposed to either hypoxia or monocrotaline. Newer models, which involve modification of classic approaches, have been developed that exhibit more severe PH and vascular lesions, which include neointimal proliferation and occlusion of small vessels. In addition, genetically manipulated mice have been generated that have provided insight into the role of specific molecules in the pulmonary hypertensive process. Unfortunately, at present, there is no perfect preclinical model that completely recapitulates human PAH. All models, however, have provided and will continue to provide invaluable insight into the numerous pathways that contribute to the development and maintenance of PH. Use of both classic and newly developed animal models will allow continued rigorous testing of new hypotheses regarding pathogenesis and treatment. This review highlights progress that has been made in animal modeling of this important human condition.

Atrial septal defect closure in a patient with “irreversible” pulmonary hypertensive arteriopathy

The presence of irreversible pulmonary hypertension in patients with atrial septal defect (ASD) is thought to preclude shunt closure. We report the case of a woman with plexiform pulmonary arteriopathy secondary to an ostium secundum ASD who was able to successfully undergo percutaneous shunt closure following therapy with chronic intravenous prostacyclin (Flolan). One year after closure, the patient was weaned off Flolan over a period of 7 months following the institution of oral Bosentan therapy. Our case illustrates how aggressive vasodilator therapy with prostaglandins may be capable of reducing pulmonary artery pressure and permitting shunt closure in a patient once considered to have "inoperable" pulmonary arteriopathy.

Plexogenic pulmonary arteriopathy in a Pembroke Welsh corgi

A 21-month-old, male Pembroke Welsh corgi was referred for investigation of respiratory distress and progressive lethargy. Cardiac evaluation revealed a grade 4 pansystolic murmur over the left and right heart base. A heart murmur, dyspnoea, cyanosis, prolonged capillary refill time and ascites led to the tentative diagnosis of a cardiac malformation with a right-to-left shunt, with likely additional pulmonary disease. Pulmonary hypertension became evident during echocardiography, when the estimated systolic pulmonary artery pressure was over 70 mmHg. Angiography revealed abnormal pulmonary vascular markings consistent with pulmonary hypertension and a small right-to-left shunting patent ductus arteriosus (PDA). The diagnosis of PDA was confirmed at postmortem examination. Histology of the pulmonary arteries showed lesions of plexogenic pulmonary arteriopathy. The question of whether both conditions were separate or part of the same clinical syndrome is discussed in this report.

Pulmonary arterial wall distensibility assessed by intravascular ultrasound in children with congenital heart disease: an indicator for pulmonary vascular disease?

BACKGROUND

Both pulmonary hypertension and pulmonary overflow are associated with functional and structural changes of the pulmonary arterial wall. Current techniques to evaluate the pulmonary vasculature neglect the pulsatile nature of pulmonary flow.

STUDY OBJECTIVES

To determine whether the dynamic properties of the pulmonary arterial wall are altered in patients with abnormal pulmonary hemodynamics due to congenital heart defects, and whether these changes are associated with the progression of pulmonary vascular disease (PVD).

PATIENTS AND METHODS

In 43 children with PVD due to congenital heart defects and 12 control subjects, pulmonary arterial pulsatility (the relative increase in vessel area during the cardiac cycle) and distensibility (the inverse of the stress/strain elastic modulus) were determined with intravascular ultrasound. Results were correlated with clinical and hemodynamic parameters.

RESULTS

Pulsatility correlated with pulmonary pulse pressure (p < 0.001), pulmonary-to-systemic vascular resistance ratio (PVR/SVR) [p = 0.001], and hemoglobin concentration (p = 0.01). However, when corrected for these variables, pulsatility did not differ between patients and control subjects. In contrast, arterial wall distensibility decreased with the severity of PVD and correlated independently with pulmonary-to-systemic arterial pressure ratio (p < 0.001) and PVR/SVR (p = 0.03), and with hemoglobin concentration (p < 0.01). Adjusted for hemodynamic variables, distensibility was still decreased in patients with PVD compared to control subjects.

CONCLUSIONS

These results demonstrate that pulmonary arterial wall distensibility is progressively decreased in PVD; moreover, this decreased distensibility is, in part, related to increased distending pressure as a result of pulmonary hypertension but also, in part, to stiffening of the arterial wall during the disease process. Arterial wall distensibility may be of additional value in the evaluation of pulmonary vasculature and ventricular workload.

Open-lung biopsy guides therapy in children

BACKGROUND

Open-lung biopsy is uncommon in children. Modern indications and outcomes are unknown.

METHODS

This is a retrospective review of 64 open-lung biopsies (58 patients) from 1976 to 1996. Open-lung biopsies were used to grade vasculopathy in 8 patients (12% of 64) with pulmonary hypertension and in 10 patients (16% of 64) with combined pulmonary hypertension and lung parenchymal disease. Forty-six biopsies (72%) were obtained to diagnose parenchymal disease. Comparisons were made between biopsies performed from 1976 to 1989 and from 1990 to 1996.

RESULTS

In the period 1990 to 1996, there were significantly more infants (p = 0.03), comorbid disease (p = 0.009), extracorporeal membrane oxygenation support (p < 10(-4)), and ventilator dependence (p = 0.05) and significantly less immunocompromise (p = 0.04). A definitive diagnosis was made in 43 of 64 cases (67%) and altered workup in 63 of 64 cases (98%). No correlation existed between Heath-Edwards grade of microangiopathy and catheterization data. Definitive diagnosis was most strongly associated with a nonimmunocompromised patient (p < 10(-4)). Although only one death (1.5%) was related to open-lung biopsy, the procedure was associated with a 30% inhospital mortality rate and an 11% morbidity rate. Of the 19 deaths, 1 patient died from the procedure, 13 died from their diseases, and 5 had support withdrawn. Death was associated with preoperative ventilator dependence (p < 10(-4)) and extracorporeal membrane oxygenation (p = 0.007).

CONCLUSIONS

Pediatric open-lung biopsy commonly alters the diagnostic workup (98%). It is recommended for children who have been supported for 2 weeks by extracorporeal membrane oxygenation and for those with combined pulmonary hypertension and parenchymal lung disease. It is less useful in immunocompromised children.

Altered Arterial Expression Patterns of Inducible and Endothelial Nitric Oxide Synthase in Pulmonary Plexogenic Arteriopathy Caused by Congenital Heart Disease

Flow-associated pulmonary hypertension leads to pulmonary plexogenic arteriopathy (PPA), a specific pulmonary vascular disease that includes vascular lesions characterized by abnormal vasodilatation and endothelial cell proliferation. Increased local production of NO has been suggested in this condition. Because reported data on the expression of endothelial NO-synthase (ecNOS) have been contradictory, we speculated that the expression of the inducible isoform of NOS (iNOS) is enhanced in this form of pulmonary hypertension. We investigated immunohistochemically the expression of ecNOS and iNOS in lung tissue of patients with flow-associated pulmonary hypertension (n = 18) and compared the findings with those in patients with increased pulmonary blood flow but normal pulmonary artery pressure (n = 10), with congestive vasculopathy (n = 6) and control subjects (n = 4). Immunoreactivity for ecNOS and iNOS was present both in normal and diseased pulmonary arteries. Marked immunoreactivity to both isoforms was present within the advanced lesions of PPA, including plexiform lesions. Semiquantitative analysis of immunoreactivity, both for ecNOS and iNOS, showed no correlation with the severity of morphologic vascular lesions (p = 0.29 and p = 0.23, respectively). In contrast to ecNOS, immunoreactivity for iNOS was increased in patients with flow-associated pulmonary hypertension compared with other patients (p = 0.02). The present study has demonstrated enhanced expression of iNOS in patients at risk for advanced PPA, but not in patients with other forms of pulmonary arteriopathy. Moreover, high expression of both ecNOS and iNOS were present in advanced lesions of PPA. These data suggest differentiated roles for different isoforms of NOS in the pathogenesis of this specific pulmonary arteriopathy.

Enhanced expression of vascular endothelial growth factor in pulmonary plexogenic arteriopathy due to congenital heart disease

Congenital heart disease (CHD) leading to increased pulmonary blood pressure and flow is an important cause of pulmonary plexogenic arteriopathy (PPA). This type of arteriopathy tends to progress to an irreversible stage, hallmarked histologically by the emergence of a number of characteristic lesions, which include concentric laminar intimal proliferation and fibrosis, and plexiform lesions. The pathogenesis of these lesions, which connote a very poor prognosis, is not well understood. Since endothelial cell proliferation has been demonstrated in these lesions, it was hypothesized that vascular endothelial growth factor (VEGF), a key mediator of angiogenesis, might play a role in their pathogenesis. Thirty-nine patients with various types of CHD, who underwent cardiac catheterization and subsequent cardiac surgery, were studied prospectively. On the basis of a detailed assessment of the type of cardiac defect, the haemodynamic abnormalities, and the histopathological features evident from open lung biopsies, taken in all instances, patients were histologically grouped into cases with moderate PPA (n=18), advanced PPA (n=7), pulmonary congestive vasculopathy (PCV, n=5), and controls lacking pulmonary hypertension or increased pulmonary blood flow (n=4). Five patients were excluded from analysis because of inadequate sample size or quality. The presence of VEGF was assessed immunohistochemically using standard procedures and was correlated with haemodynamic and histological data. Immunoreactive VEGF was detected in pulmonary arterial smooth muscle cells and endothelial cells in 13 out of 34 cases and was more frequent and more pronounced in patients with the histological lesions of advanced PPA than in those with moderate PPA (p<0.01). VEGF positivity was particularly prominent in the lesions characteristic of advanced PPA. No difference in VEGF expression was observed between controls, PVC, and moderate PPA cases. Measured haemodynamic parameters did not differ significantly between VEGF-positive and VEGF-negative cases. We conclude that VEGF may play a role in the angioproliferative changes of advanced PPA.

Exploration of the pulmonary circulation. Festschrift to Professor Donald Heath

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Plexogenic arteriopathy

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Congenital pulmonary lymphangiectasis presenting as a unilateral hyperlucent lung

Congenital pulmonary lymphangiectasis can be a cause of respiratory distress of the newborn infant. We present a case of congenital pulmonary lymphangiectasis presenting as a unilateral hyperlucent lung. Such a presentation has only once been previously described.

Thrombotic lesions in primary plexogenic arteriopathy. Similar pathogenesis or complication?

In 78 patients with primary plexogenic arteriopathy (PPA), numbers of organized and recanalized thrombi were established in histologic slides of lung tissue and expressed per square centimeter of section. Three control groups of ten individuals each were used: normal, plexogenic arteriopathy secondary to ventricular septal defect, and hypoxic pulmonary hypertension. Thrombotic lesions were scarce in normal individuals but numerous in all three groups with pulmonary hypertension. There is also a positive correlation with age. Thrombotic lesions are absent or scarce in children but more common in adults, even in normal control subjects and particularly in pulmonary hypertension by whatever cause. In PPA there is likely to be a relation with the duration of illness but not with the stage of the disease. The complete pattern of plexogenic arteriopathy may develop in the absence of thrombotic lesions, which clearly are not essential for its pathogenesis. Rather than being part specifically of PPA, as sometimes suggested, thrombotic lesions complicate various types of hypertensive pulmonary vascular disease. Apparently the combination of sustained pulmonary hypertension and age, possibly through endothelial injury, may elicit thrombosis and its sequelae, which in turn may aggravate the pulmonary arterial pressure.

Pulmonary wedge angiography for prediction of pulmonary vascular disease in Down syndrome

We performed high resolution pulmonary wedge angiography (PWA) and conventional hemodynamics to predict the reversibility of structural pulmonary vascular disease. Sixty-one pulmonary wedge angiograms were performed on 41 patients with intracardiac shunts and Down syndrome (median age 8 months). Balloon occlusion wedge angiograms were analyzed for (1) monopedial branches from the distal 10 mm of muscular arteries, (2) capillary blush, (3) tapering indices, and (4) tortuosity. Twenty-five patients had open lung biopsy, graded by the Health Edwards classification, and analyzed morphometrically. Pulmonary vascular resistance of > or = 6 units was 100% sensitive and 94% specific for Heath Edwards Grade III-IV. A monopedial count < 3 vessels was 83% sensitive and 100% specific for Heath Edwards Grade III-IV. Abnormal capillary blush was 83% sensitive and 69% specific for Heath Edwards Grade III-IV. Tapering indices and tortuosity showed no significant correlation with lung biopsy. A combination of pulmonary vascular resistance < 6 units, monopedial count > or = 3, and normal capillary blush was 100% sensitive and specific for Heath Edwards Grade 0-II, and a combination of pulmonary vascular resistance > or = 6 units, monopedial count < 3, and abnormal capillary blush was 100% sensitive and specific for Heath Edwards Grade III-IV. Using the 3 criteria, Heath Edwards Grade was accurately predicted in 17 patients. In 4 patients, only 2 criteria were available. Morphometric analysis showed an inverse relationship between the lowest monopedial count and the number of occlusive vessels per cm of tissue, r = -0.74 p < 0.001. Arteries showing intimal and/or medial thickening causing > 90% luminal narrowing were scored as "occlusive." These results show that when the hemodynamic and pulmonary wedge angiography data are concordant, the structural changes of pulmonary vascular disease can be accurately predicted and lung biopsy may be avoided.

Pulmonary vascular disease in infants with complete atrioventricular septal defect

In order to assess incidence and time of occurrence of pulmonary vascular disease, the lungs of 49 patients were studied histologically. Thirty-four lung specimens were obtained at autopsy, and 15 were open lung biopsies. Patients consisted of 24 males and 25 females ranging in age from 10 days to 14 years (median 9 months); 37 had Down's syndrome. Overall incidence of irreversible pulmonary vascular disease (grade 3 or more) under 1 year of age was 34.6%; grade 4 of pulmonary vascular disease was observed only in Down patients. In correlating pulmonary vascular resistance, measured during heart catheterization, with pulmonary vascular disease severity at histology, 6 out of 7 patients with pulmonary vascular resistance over 7 units per metre squared showed grade 4 of pulmonary vascular disease, and of these 4 were under 1 year of age. These findings suggest that a significant rate of pulmonary vascular disease occurs under 1 year of age, with most severe degrees in the time interval 7-12 months. They show that good correlation exists between pulmonary vascular resistance over 7 units per metre squared and grade 4 of pulmonary vascular disease. They demonstrate that the most severe pulmonary vascular disease is seen in Down's syndrome. Finally, they indicate that early surgical correction is mandatory and should be accomplished within 6 months of age.