Systemic collateral supply in patients with chronic thromboembolic and primary pulmonary hypertension: assessment with multi-detector row helical CT angiography

Inflammation and ischemia-induced lung angiogenesis

A role for inflammation in modulating the extent of angiogenesis has been shown for a number of organs. The present study was undertaken to evaluate the importance of leukocyte subpopulations for systemic angiogenesis of the lung after left pulmonary artery ligation (LPAL) in a mouse model of chronic pulmonary thromboembolism. Since we (24) previously showed that depletion of neutrophils did not alter the angiogenic outcome, we focused on the effects of dexamethasone pretreatment (general anti-inflammatory) and gadolinium chloride treatment (macrophage inactivator) and studied Rag-1(-/-) mice (T/B lymphocyte deficient). We measured inflammatory cells in bronchoalveolar lavage fluid and lung homogenate macrophage inflammatory protein-2 (MIP-2) and IL-6 protein levels within 24 h after LPAL and systemic blood flow to the lung 14 days after LPAL with labeled microspheres as a measure of angiogenesis. Blood flow to the left lung was significantly reduced after dexamethasone treatment compared with untreated control LPAL mice (66% decrease; P < 0.05) and significantly increased in T/B lymphocyte-deficient mice (88% increase; P < 0.05). Adoptive transfer of splenocytes (T/B lymphocytes) significantly reversed the degree of angiogenesis observed in the Rag-1(-/-) mice back to the level of control LPAL. Average number of lavaged macrophages for each group significantly correlated with average blood flow in the study groups (r(2) = 0.9181; P = 0.01 different from 0). Despite differences in angiogenesis, left lung homogenate MIP-2 and IL-6 did not differ among study groups. We conclude that inflammatory cells modulate the degree of angiogenesis in this lung model where lymphocytes appear to limit the degree of neovascularization, whereas monocytes/macrophages likely promote angiogenesis.

The role of CXCR2 in systemic neovascularization of the mouse lung

We previously showed increased expression of the ELR+, CXC chemokines in the lung after left pulmonary artery obstruction. These chemokines have been shown in other systems to bind their G protein-coupled receptor, CXCR2, and promote systemic endothelial cell proliferation, migration, and capillary tube formation. In the present study, we blocked CXCR2 in vivo using a neutralizing antibody and also studied mice that were homozygous null for CXCR2. To estimate the extent of neovascularization in this model, we measured systemic blood flow to the left lung 14 days after left pulmonary artery ligation (LPAL). We found blood flow significantly reduced (67% decrease) with neutralizing antibody treatment compared with controls. However, blood flow was not altered in the CXCR2-deficient mice compared with wild-type controls after LPAL. To test for ligand availability, we measured macrophage inflammatory protein (MIP)-2 in lung homogenates after LPAL, because this is the predominant CXC chemokine previously shown to be increased after LPAL ( 22 ). MIP-2 protein was two- to fourfold higher in the left lung relative to the right lung in all treatment groups 4 h after LPAL and this increase did not differ among groups. We speculate that the CXCR2-deficient mice have compensatory mechanisms that mitigate their lack of gene expression and conclude that CXCR2 contributes to chemokine-induced systemic angiogenesis after pulmonary artery obstruction.

Diagnosis of pulmonary arterial hypertension

Accurate diagnosis of pulmonary arterial hypertension is a challenging and complex process that requires a high index of clinical suspicion from even the most astute clinician. This article discusses the use of a variety of noninvasive tests that can help define the population of patients in whom invasive cardiac catheterization should be pursued. It points out the vagaries and limitations of electrocardiography and the radiographic and echocardiographic clues to the diagnosis. Ultimately, right- and, often, concomitant left-heart catheterization is required to establish the diagnosis and distinguish pulmonary arterial hypertension from pulmonary venous hypertension.

Hypertension pulmonaire postembolique

INTRODUCTION

Chronic thromboembolic pulmonary hypertension (CTEPH) is a rare disease characterized by the persistence of thromboemboli obstructing the pulmonary arteries as an organized tissue. The consequence is an increase in pulmonary vascular resistance resulting in pulmonary hypertension (PH) and progressive right heart failure.

BACKGROUND

It is difficult to recognize the postembolic nature of PH because there is no known history of thromboembolic disease in more than 50% of cases. Diagnosis is based on the presence of mismatched segmental defects in the ventilation-perfusion scanning. When CTEPH is suspected, pulmonary angiography and high-resolution CT scan are required to establish the diagnosis and to assess the operability. Pulmonary angiography is always performed in conjunction with a diagnostic right heart catheterization, which is required to confirm the diagnosis of PH and to determine the degree of hemodynamic impairement. If there is a good correlation between the pulmonary vascular resistance and the anatomical obstruction, pulmonary endarterectomy (PEA) must be proposed. Otherwise, vasodilator and antiproliferative treatments and lung transplantation represent interesting alternatives.

VIEWPOINT AND CONCLUSION

PEA remains the treatment of choice for eligible patients. Nevertheless, there is a need to conduct randomized trials to assess the efficacy of novel medical therapies in some situations: (1) in inoperable CTEPH due to distal lesions, (2) before PEA (therapeutic bridge) in patients who are considered "high risk" due to extremely poor hemodynamics, (3) in patients with persistent pulmonary hypertension after surgery.

Findings on Submillimeter MDCT Are Predictive of Operability in Chronic Thromboembolic Pulmonary Hypertension

OBJECTIVE

The purpose of this study was to investigate whether preoperative 16-MDCT at 0.7-mm collimation can be used to predict the presence of an endarterectomy plane by depicting abnormal thickening of the walls of central pulmonary arteries in patients with chronic thromboembolic pulmonary hypertension. MDCT scans of 40 patients were reviewed retrospectively by two radiologists who were blinded to surgical findings.

CONCLUSION

The sensitivity, specificity, and accuracy of MDCT in prediction of the presence of an endarterectomy plane were 99%, 80%, and 96%. Bilateral absence of an endarterectomy plane correlated with postoperative mortality according to Fisher's exact test results (p = 0.004). Submillimeter 16-MDCT therefore may be useful in predicting operability in chronic thromboembolic pulmonary hypertension.

Embolization for hemoptysis in chronic thromboembolic pulmonary hypertension: report of two cases and a review of the literature

Hemoptysis is a known complication in patients with bronchial artery hypertrophy due to a variety of chronic pulmonary disorders. Bronchial artery hypertrophy is observed in most patients with chronic thromboembolic pulmonary hypertension (CTEPH), but surprisingly little is known about the incidence of hemoptysis in these patients. In this paper, we report on 2 patients with CTEPH and recurrent severe hemoptysis, who were treated by bronchial artery embolization. One patient recovered and 1 patient died as a consequence of the bleeding. A systematic review revealed 21 studies on the underlying pathology in 1,844 patients with moderate to severe hemoptysis. CTEPH was reported to be the cause of bleeding in 0.1% (n = 2), pulmonary arterial hypertension without chronic thromboembolic disease in 0.2% (n = 4), and acute pulmonary embolism in 0.7% (n = 12) of the patients. In contrast to this, 5 patients (6%) in our own series of 79 CTEPH patients suffered from moderate to severe hemoptysis requiring medical intervention. Severe hemoptysis appears to be an uncommon, but possibly underreported, life-threatening complication in CTEPH patients. As most CTEPH patients require life-long anticoagulants a therapeutic dilemma may ensue. Therefore, we propose that even mild hemoptysis in CTEPH patients warrants prompt evaluation, and treatment by embolization should be offered as first choice in CTEPH patients.

Pulmonary Arteriovenous Malformation Treated with Embolotherapy: Systemic Collateral Supply at Multidetector CT Angiography after 2–20-year Follow-up

PURPOSE

To retrospectively evaluate frequency of systemic arterial collateral supply to treated pulmonary arteriovenous malformations (PAVMs) in long-term follow-up with multi-detector row helical computed tomography (CT).

MATERIALS AND METHODS

Institutional review board approval was obtained, with waiver of informed consent. Thirty-two patients (19 male, 13 female; mean age, 43 years) underwent follow-up multi-detector row helical CT angiography of the chest (collimation, 16x0.75 mm) 2 or more years after embolotherapy of PAVMs. The study group had a history of successful embolotherapy of 53 PAVMs and a mean of 9 years of follow-up (range, 2-20 years). A search for abnormal systemic arteries was based on analysis of thin-collimated contiguous transverse CT scans and two- and three-dimensional images including maximum intensity projections and volume-rendered images. Statistical comparison was performed with the Fisher exact test (categoric variables) and Wilcoxon rank sum test (continuous variables).

RESULTS

At CT, 13 patients (group 1) had abnormally enlarged systemic arteries and 19 patients (group 2) had no abnormal arteries. In group 1, 32 abnormally enlarged arteries were seen-five bronchial and 27 nonbronchial arteries (14 inferior phrenic, six musculophrenic, five internal mammary, two intercostal). The degree of enlargement was moderate for 26 arteries and marked for six. There were no significant differences between groups for (a) clinical characteristics of patients, including history of surgery before or after embolotherapy (P=.7); (b) anatomic structures of treated PAVMs; and (c) embolization procedures and their effectiveness. The number of patients with features suggestive of lung infarction in the days or months after embolotherapy was significantly higher in group 1 (P=.04). On CT angiograms, the number of patients with features suggestive of sequelae of lung infarction was significantly higher in group 1 (P=.02). There were no symptomatic differences attributable to systemic collateral supply between groups; in particular, there was no hemoptysis in group 1.

CONCLUSION

Abnormally enlarged systemic arteries were present in 13 of 32 patients, in whom there was a significantly higher frequency of clinical and/or radiographic features suggestive of lung infarction after embolotherapy.

Congenital and acquired pulmonary artery anomalies in the adult: radiologic overview

Various congenital and acquired anomalies may affect the pulmonary arteries in adult patients. Congenital anomalies (proximal interruption, anomalous origin of the left pulmonary artery [pulmonary artery sling], and idiopathic dilatation of the pulmonary trunk) are usually found incidentally at chest radiography or computed tomography (CT). Acquired anomalies include diffuse or focal enlargement of the arteries because of pulmonary hypertension, aneurysm, and intravascular pulmonary metastasis; decreased arterial diameter because of bronchial carcinoma, mediastinal fibrosis, and Takayasu arteritis; and intraluminal filling defects due to pulmonary thromboembolism and pulmonary artery sarcoma. An awareness of the radiologic manifestations of the disease entities and potential pulmonary artery complications secondary to infection or vasculitis may enable an early diagnosis. CT angiography is becoming the standard method for evaluating patients in whom the presence of pulmonary embolism is suspected. CT assessment of the extent of heart effects in patients with pulmonary hypertension and pulmonary embolism is particularly important because such effects largely determine the prognosis.

Chronic thromboembolic pulmonary hypertension — assessment by magnetic resonance imaging

Chronic thromboembolic pulmonary hypertension (CTEPH) is a severe disease that has been ignored for a long time. However, with the development of improved therapeutic modalities, cardiologists and thoracic surgeons have shown increasing interest in the diagnostic work-up of this entity. The diagnosis and management of chronic thromboembolic pulmonary hypertension require a multidisciplinary approach involving the specialties of pulmonary medicine, cardiology, radiology, anesthesiology and thoracic surgery. With this approach, pulmonary endarterectomy (PEA) can be performed with an acceptable mortality rate. This review article describes the developments in magnetic resonance (MR) imaging techniques for the diagnosis of chronic thromboembolic pulmonary hypertension. Techniques include contrast-enhanced MR angiography (ce-MRA), MR perfusion imaging, phase-contrast imaging of the great vessels, cine imaging of the heart and combined perfusion-ventilation MR imaging with hyperpolarized noble gases. It is anticipated that MR imaging will play a central role in the initial diagnosis and follow-up of patients with CTEPH.