The bronchial arteries and their anastomoses in the human lung

Bronchial artery embolization using small particles is safe and effective: a single center 12-year experience

BACKGROUND

Bronchial artery embolization (BAE) using particles is an established treatment for hemoptysis. The use of polyvinyl alcohol (PVA) with a particle size of 300 µm or larger is thought to reduce the risk of non-target embolization but may result in more proximal vessel occlusion than is ideal, resulting in a high rate of early recurrent hemorrhage.

OBJECTIVE

This study evaluates the safety and efficacy of BAE using PVA particles with a size of less than 300 µm.

METHODS

All patients who underwent BAE between 2010 and 2022 at a tertiary center were included. Demographic data, etiology and volume of hemoptysis, technical and clinical success, procedure-related complications, and follow-up information were collected from patients' electronic records. 150-250 µm PVA particles were used to commence embolization in all patients with the subsequent use of larger-sized particles in some individuals. The Kaplan-Meier method was used to estimate recurrence and survival rates.

RESULTS

One hundred forty-four patients underwent 189 embolization procedures between 2010 and 2022 and were followed up for a median of 35 months [IQR 19-89]. 150 µm to 250 µm PVA particles were used as the sole embolic agent in 137 cases. Hemoptysis recurred within 30 days in 7%. The median time to repeat intervention was 144 days [IQR 42-441]. Seventeen out of 144 patients had a pulmonary artery branch pseudoaneurysm. The rate of major complications was 1% with no instances of stroke or spinal artery ischemia. Thirty-day mortality was 2% (4/189).

CONCLUSION

BAE using 150-250 µm PVA particles is safe and effective with few complications and low rates of early hemoptysis recurrence.

CLINICAL RELEVANCE STATEMENT

BAE using small particles is likely to improve outcomes, particularly the rate of early recurrence, in patients with hemoptysis, without an increase in procedural complications.

KEY POINTS

BAE is a safe and effective treatment for patients with hemoptysis. Using small PVA particles in BAE has few complications and low rates of early recurrence. Pulmonary artery pseudoaneurysms should be actively sought in those with hemoptysis undergoing BAE.

Clinical outcomes and factors associated with pulmonary infarction following acute pulmonary embolism: a retrospective observational study at a US academic centre

OBJECTIVE

Pulmonary infarction is a common clinical and radiographic finding in acute pulmonary embolism (PE), yet the clinical relevance and prognostic significance of pulmonary infarction remain unclear. The study aims to investigate the clinical features, radiographic characteristics, impact of reperfusion therapy and outcomes of patients with pulmonary infarction.

DESIGN, SETTING AND PARTICIPANTS

A retrospective cohort study of 496 adult patients (≥18 years of age) diagnosed with PE who were evaluated by the PE response team at a tertiary academic referral centre in the USA. We collected baseline characteristics, laboratory, radiographic and outcome data. Statistical analysis was performed by Student's t-test, Mann-Whitney U test, Fischer's exact or χ² test where appropriate. Multivariate logistic regression was used to evaluate potential risk factors for pulmonary infarction.

RESULTS

We identified 143 (29%) cases of pulmonary infarction in 496 patients with PE. Patients with infarction were significantly younger (52±15.9 vs 61±16.6 years, p<0.001) and with fewer comorbidities. Most infarctions occurred in the lower lobes (60%) and involved a single lobe (64%). The presence of right ventricular (RV) strain on CT imaging was significantly more common in patients with infarction (21% vs 14%, p=0.031). There was no significant difference in advanced reperfusion therapy, in-hospital mortality, length of stay and readmissions between groups. In multivariate analysis, age and evidence of RV strain on CT and haemoptysis increased the risk of infarction.

CONCLUSIONS

Radiographic evidence of pulmonary infarction was demonstrated in nearly one-third of patients with acute PE. There was no difference in the rate of reperfusion therapies and the presence of infarction did not correlate with poorer outcomes.

Haemoptysis in Pulmonary Arterial Hypertension Associated with Congenital Heart Disease: Insights on Pathophysiology, Diagnosis and Management

Haemoptysis represents one of the most severe major bleeding manifestations in the clinical course of pulmonary arterial hypertension (PAH) associated with congenital heart disease (CHD). Accumulating evidence indicates that dysfunction of the pulmonary vascular bed in the setting of PAH predisposes patients to increased hemorrhagic diathesis, resulting in mild to massive and life-threatening episodes of haemoptysis. Despite major advances in PAH targeted treatment strategies, haemoptysis is still correlated with substantial morbidity and impaired quality of life, requiring a multidisciplinary approach by adult CHD experts in tertiary centres. Technological innovations in the field of diagnostic and interventional radiology enabled the application of bronchial artery embolization (BAE), a valuable tool to efficiently control haemoptysis in modern clinical practice. However, bleeding recurrences are still prevalent, implying that the optimum management of haemoptysis and its implications remain obscure. Moreover, regarding the use of oral anticoagulation in patients with haemoptysis, current guidelines do not provide a clear therapeutic strategy due to the lack of evidence. This review aims to discuss the main pathophysiological mechanisms of haemoptysis in PAH-CHD, present the clinical spectrum and the available diagnostic tools, summarize current therapeutic challenges, and propose directions for future research in this group of patients.

Pulmonary vasculitis in Hughes-Stovin syndrome (HSS): a reference atlas and computed tomography pulmonary angiography guide-a report by the HSS International Study Group

Introduction

Hughes-Stovin syndrome (HSS) is a systemic vasculitis characterized by widespread venous/arterial thrombosis and pulmonary artery aneurysms (PAAs), which is associated with serious morbidity and mortality. All fatalities reported in HSS resulted from unpredictable fatal suffocating hemoptysis. Therefore, it is necessary to recognize pulmonary complications at an early stage of the disease.

Objectives

The aims of this study are to develop a reference atlas of images depicting the characteristic features of HSS by computed tomography pulmonary angiography (CTPA). To make a guide for physicians by developing a classification of PAAs according to the severity and risk of complications associated with each distinct lesion type.

Methods

The Members of the HSS International Study Group (HSSISG) collected 42 cases, with high-quality CTPA images in one radiology station and made reconstructions from the source images. These detailed CTPA studies were reviewed for final image selection and approved by HSSISG board members. We classified these findings according to the clinical course of the patients.

Results

This atlas describes the CTPA images that best define the wide spectrum of pulmonary vasculitis observed in HSS. Pulmonary aneurysms were classified into six radiographic patterns: from true stable PAA with adherent in-situ thrombosis to unstable leaking PAA, BAA and/or PAP with loss of aneurysmal wall definition (most prone to rupture), also CTPA images demonstrating right ventricular strain and intracardiac thrombosis.

Conclusion

The HSSISG reference atlas is a guide for physicians regarding the CTPA radiological findings, essential for early diagnosis and management of HSS-related pulmonary vasculitis.

Key Points • The Hughes-Stovin syndrome (HSS) is a systemic vasculitis characterized by extensive vascular thrombosis and pulmonary artery aneurysms (PAAs) that can lead to significant morbidity and mortality. • All fatalities reported in HSS were related to unpredictable massive hemoptysis; therefore, it is critical to recognize pulmonary complications at an early stage of the disease. • The HSS International Study Group reference atlas  classifies pulmonary vasculitis in HSS at 6 different stages of the disease process and defines the different radiological patterns of pulmonary vasculitis notably pulmonary artery aneurysms, as detected by computed tomography pulmonary angiography (CTPA). • The main aim of the classification is to make a guide for physicians about this rare syndrome. Such a scheme has never been reached before since the first description of the syndrome by Hughes and Stovin since 1959. This classification will form the basis for future recommendations regarding diagnosis and treatment of this syndrome.

CT for Evaluation of Hemoptysis

Hemoptysis, which is defined as expectoration of blood from the alveoli or airways of the lower respiratory tract, is an alarming clinical symptom with an extensive differential diagnosis. CT has emerged as an important noninvasive tool in the evaluation of patients with hemoptysis, and the authors present a systematic but flexible approach to CT interpretation. The first step in this approach involves identifying findings of parenchymal and airway hemorrhage. The second step is aimed at determining the mechanism of hemoptysis and whether a specific vascular supply can be implicated. Hemoptysis can have primary vascular and secondary vascular causes. Primary vascular mechanisms include chronic systemic vascular hypertrophy, focally damaged vessels, a dysplastic lung parenchyma with systemic arterial supply, arteriovenous malformations and fistulas, and bleeding at the capillary level. Evaluating vascular mechanisms of hemoptysis at CT also entails determining if a specific vascular source can be implicated. Although the bronchial arteries are responsible for most cases of hemoptysis, nonbronchial systemic arteries and the pulmonary arteries are important potential sources of hemoptysis that must be recognized. Secondary vascular mechanisms of hemoptysis include processes that directly destroy the lung parenchyma and processes that directly invade the airway. Understanding and employing this approach allow the diagnostic radiologist to interpret CT examinations accurately in patients with hemoptysis and provide information that is best suited to directing subsequent treatment. ^©RSNA, 2021.

Transpleural systemic artery-to-pulmonary artery communications in the absence of chronic inflammatory lung disease. A case series and review of the literature

AIM

To describe the causes and computed tomography (CT) and angiographic appearances of transpleural systemic artery-to-pulmonary artery shunts in patients without chronic inflammatory lung disease and determine their best management.

MATERIALS AND METHODS

All patients referred to a tertiary referral unit between January 2009 and January 2020 in whom a diagnosis of a systemic-to-pulmonary artery communication without underlying chronic inflammatory lung disease was subsequently made have been included in this report. Medical records and imaging findings were reviewed retrospectively.

RESULTS

Ten patients (male: female ratio = 7:3; median age 42 years [range 22-70 years]) with systemic artery-to-pulmonary artery shunts without chronic inflammatory lung disease were identified. Five were misdiagnosed as having a pulmonary arteriovenous malformation and had been referred for embolisation. In six patients, there was either a history of accidental or iatrogenic thoracic trauma or of inflammatory disease involving the pleura, and in two patients, in whom a previous medical history could not be obtained, there were CT features suggesting previous pleural inflammatory disease. Two shunts were thought to be congenital. All individuals were asymptomatic other than one with localised thoracic discomfort that dated from the time of surgery. All patients were managed conservatively and have remained well with a median follow-up of 4.5 years (range 1-11.3 years).

CONCLUSIONS

Localised transpleural systemic artery-to-pulmonary artery shunts in the absence of chronic inflammatory lung disease are usually related to previous thoracic trauma/intervention or abdominal or pulmonary sepsis involving a pleural or diaphragmatic surface. Congenital shunts are rare. The present study and much of the literature supports conservative management.

Pulmonary infarction in acute pulmonary embolism

Pulmonary infarction results from occlusion of the distal pulmonary arteries leading to ischemia, hemorrhage and ultimately necrosis of the lung parenchyma. It is most commonly caused by acute pulmonary embolism (PE), with a reported incidence of around 30%. Following an occlusion of the pulmonary artery, the bronchial arteries are recruited as primary source of perfusion of the pulmonary capillaries. The relatively higher blood pressure in the bronchial circulation causes an increase in the capillary blood flow, leading to extravasation of erythrocytes (i.e. alveolar hemorrhage). If this hemorrhage cannot be resorbed, it results in tissue necrosis and infarction. Different definitions of pulmonary infarction are used in literature (clinical, radiological and histological), although the diagnosis is nowadays mostly based on radiological characteristics. Notably, the infarcted area is only replaced by a fibrotic scar over a period of months. Hence and formally, the diagnosis of pulmonary infarction cannot be confirmed upon diagnosis of acute PE. Little is known of the impact and relevance of pulmonary infarction in acute PE, and whether specific management strategies should be applied to prevent and/or treat complications such as pain, pneumonia or post-PE syndrome. In this review we will summarize current knowledge on the pathophysiology, epidemiology, diagnosis and prognosis of pulmonary infarction in the setting of acute PE. We highlight the need for dedicated studies to overcome the current knowledge gaps.

Hyperbaric oxygen therapy to prevent central airway stenosis after lung transplantation

BACKGROUND

Central airway stenosis (CAS) is a severe airway complication after lung transplantation associated with bronchial ischemia and necrosis. We sought to determine whether hyperbaric oxygen therapy (HBOT), an established treatment for tissue ischemia, attenuates post-transplant bronchial injury.

METHODS

We performed a randomized, controlled trial comparing usual care with HBOT (2 atm absolute for 2 hours × 20 sessions) in subjects with extensive airway necrosis 4 weeks after transplantation. Endobronchial biopsies were collected at 4, 7, and 10 weeks after transplantation for a quantitative polymerase chain reaction. Coprimary outcomes were incidence of airway stenting and acute cellular rejection (ACR) at 1 year.

RESULTS

The trial was stopped after enrolling 20 subjects (n = 10 per group) after a pre-planned interim analysis showed no difference between usual care and HBOT groups in stenting (both 40%), ACR (70% and 40%, respectively), or CAS (40% and 60%, respectively). Time to first stent placement (median [interquartile range]) was significantly shorter in the HBOT group (150 [73-150] vs 186 [167-206] days, p < 0.05). HIF gene expression was significantly increased in donor tissues at 4, 7, and 10 weeks after transplantation but was not altered by HBOT. Subjects who developed CAS or required stenting had significantly higher HMOX1 and VEGFA expression at 4 weeks (both p < 0.05). Subjects who developed ACR had significant FLT1, TIE2, and KDR expression at 4 weeks (all p < 0.05).

CONCLUSIONS

Incidence of CAS is high after severe, established airway necrosis after transplantation. HBOT does not reduce CAS severity or stenting. Elevated HMOX1 and VEGFA expressions appear to associate with airway complications.

Non-bronchial causes of haemoptysis: imaging and interventions

Purpose

To describe non-bronchial causes of haemoptysis on imaging and the role of interventional radiology in their management from cases of haemoptysis archived from our database at a tertiary care, federally funded institution.

Material and methods

Retrospective analysis of cases that presented with haemoptysis in our institution from 2008 to 2013 was done, and details of cases in which the bleeding was from a non-bronchial source were archived and details of imaging and treatment were recorded.

Results

Retrospective analysis of patients presenting with haemoptysis yielded 24 (n = 24) patients having haemoptysis from non-bronchial sources. Causes of haemoptysis were: Rasmussen aneurysms (n = 12/24), costocervical trunk pseudoaneurysm (n = 1/24), left internal mammillary artery pseudoaneurysm (n = 1/24), left ventricular aneurysms (n = 3/24), pulmonary arteriovenous malformations (AVMs) (n = 5/24), and proximal interruption of pulmonary artery (n = 2/24). Imaging and interventional radiology management are described in detail.

Conclusions

Haemoptysis can be from non-bronchial sources, which may be either from systemic or pulmonary arteries or cardio-pulmonary fistulas. Bronchial computed tomography angiography (CTBA), if feasible, must always be considered before bronchial artery embolisation because it precisely identifies the source of haemorrhage and vascular anatomy that helps the interventional radiologist in pre-procedural planning. This circumvents chances of re-bleed if standard bronchial artery embolisation is done without CTBA.

Synchrotron-based phase-contrast micro-CT as a tool for understanding pulmonary vascular pathobiology and the 3-D microanatomy of alveolar capillary dysplasia

This study aimed to explore the value of synchrotron-based phase-contrast microcomputed tomography (micro-CT) in pulmonary vascular pathobiology. The microanatomy of the lung is complex with intricate branching patterns. Tissue sections are therefore difficult to interpret. Recruited intrapulmonary bronchopulmonary anastomoses (IBAs) have been described in several forms of pulmonary hypertension, including alveolar capillary dysplasia with misaligned pulmonary veins (ACD/MPV). Here, we examine paraffin-embedded tissue using this nondestructive method for high-resolution three-dimensional imaging. Blocks of healthy and ACD/MPV lung tissue were used. Pulmonary and bronchial arteries in the ACD/MPV block had been preinjected with dye. One section per block was stained, and areas of interest were marked to allow precise beam-alignment during image acquisition at the X02DA TOMCAT beamline (Swiss Light Source). A ×4 magnifying objective coupled to a 20-µm thick scintillating material and a sCMOS detector yielded the best trade-off between spatial resolution and field-of-view. A phase retrieval algorithm was applied and virtual tomographic slices and video clips of the imaged volumes were produced. Dye injections generated a distinct attenuation difference between vessels and surrounding tissue, facilitating segmentation and three-dimensional rendering. Histology and immunohistochemistry post-imaging offered complementary information. IBAs were confirmed in ACD/MPV, and the MPVs were positioned like bronchial veins/venules. We demonstrate the advantages of using synchrotron-based phase-contrast micro-CT for three-dimensional characterization of pulmonary microvascular anatomy in paraffin-embedded tissue. Vascular dye injections add additional value. We confirm intrapulmonary shunting in ACD/MPV and provide support for the hypothesis that MPVs are dilated bronchial veins/venules.

Non-aortic vascular findings on chest CT angiogram: including arch vessels and bronchial arteries

CT angiogram (CTA) has become the modality of choice for imaging of thoracic vascular pathologies, involving the aorta and the pulmonary arteries. Apart from showing exquisite details of these large arteries, pathologies and anatomic variants of their branches can also be studied to a great extent. The major branches of aortic arch can be affected by a wide variety of pathologies ranging from atherosclerosis to trauma and vasculitis. Bronchial arteries in spite of supplying only 1% of lung parenchyma can become hypertrophied in various congenital and acquired conditions, becoming an important source of collateral circulation as well as a source for life threatening hemoptysis. CT also plays an important role in diagnosis of vascular compression at the thoracic outlet. With advances in CT technology, the acquisition, interpretation and clinical applications of CT angiography will continue to grow in the years to come.

A literature review of systemic to pulmonary collaterals in preterm infants to emphasise their existence and clinical importance

AIM

Cardiorespiratory physiology plays an important role in neonatal care with increasing utility of point-of-care ultrasound. This review is to bring to light the importance of systemic to pulmonary collaterals (SPCs) in the preterm population without congenital heart disease (CHD) and provide a useful diagnostic tool to the neonatologist performing a cardiac ultrasound.

METHODS

Medline, PubMed, EMBASE and the Internet were searched up to November 2017 for articles in English which included SPCs in preterm infants without CHD. This comprised title, abstract and full-text screening of relevant data.

RESULTS

A total of 10 studies which included case reports, retrospective observational studies and one small prospective cohort study were identified and analysed in detail. The studies had varying focus such as variable incidence, clinical presentation, association with chronic lung disease, pathophysiology and clinical importance of SPCs. SPCs were overall thought to be prevalent, underdiagnosed and of clinical significance in preterm infants.

CONCLUSION

Systemic to pulmonary collaterals are a potential left-to-right shunt in preterm infants and may contribute to worsening chronic lung disease (CLD) or heart failure. They should be carefully looked for when performing bedside cardiac ultrasound as the findings can mimic those seen in patent ductus arteriosus (PDA).

An Interventionalist's Guide to Hemoptysis in Cystic Fibrosis

Massive hemoptysis occurs in a minority of patients with cystic fibrosis, with an annual incidence of 1%. Although rare, massive hemoptysis can be a severe and potentially fatal complication of this disease. Beyond the acute life-threatening event, hemoptysis in patients with cystic fibrosis has been associated with faster decline in lung function, accelerated need for lung transplant, and increased mortality. The bronchial arteries are the culprit vessels in over 90% of cases of hemoptysis. This normally quiescent vascular system undergoes remarkable hypertrophy, collateralization, and angiogenesis before the onset of hemoptysis, introducing numerous pitfalls for the interventionalist. However, in experienced hands, bronchial artery embolization is a safe and potentially lifesaving therapy. Preprocedural noninvasive imaging, specifically computed tomographic angiography, has been repeatedly validated for helping to localize the likely site of bleeding, characterizing pertinent arterial anatomy, and promoting efficient and effective intervention; it has been recommended for all stable patients with hemoptysis. Success in the angiographic suite requires a thorough understanding of normal and variant bronchial arterial anatomy, appropriate patient selection, and a meticulous embolization technique. A meticulous approach to imaging and intervention, conscientious of both visualized and nonvisualized collateral pathways and nontarget vessels, can minimize potentially devastating complications. This review summarizes the current literature, modern procedural techniques, and emerging controversies, serving to guide an evolving approach to management of patients with cystic fibrosis and hemoptysis. ^©RSNA, 2018.

Bronchial Artery Embolization with Large Sized (700-900 µm) Tris-acryl Microspheres (Embosphere) for Massive Hemoptysis: Long-Term Results (Clinical Research)

PURPOSE

To investigate the safety, efficacy and long-term results of bronchial artery embolization with microsphere particles (Embosphere^® Microspheres, BioSphere Medical, Rockland, MA) 700-900 µm in size for massive hemoptysis.

METHODS

One hundred and seventy-four patients (94 female, 80 male; mean age 39.4 ± 5.7) who had bronchial artery embolization for massive hemoptysis between January 2010 and October 2015 were incorporated in the study. Patients had hemoptysis with a mean volume of 525 ± 150 mL (median 500 mL, range 300-1200 mL) over a 24-h period. Underlying pathologies included bronchial artery hypertrophy due to bronchiectasis (56.3% [98/174]), lung cancer (29.9% [52/174]), tuberculosis (10.3% [18/174]) and the rest remained idiopathic (3.4% [6/174]). Mean bronchial artery diameter before the intervention was 3.8 ± 1.5 mm (median 4 mm, range 3.1-7.5 mm). Median follow-up period was 56 months (range 10-82 months). Primary objectives were the technical and clinical success.

RESULTS

Technical success was 100%. Clinical success for preventing massive hemoptysis was 91.9% (160/174). There was no procedure-related mortality or morbidities. Minor complications such as chest pain were observed in nine patients (5.0%). Recurrent hemoptysis (8.1%) was observed within 6 months in 14 patients, ten of whom were treated with a second embolization session and the remaining four with a total of three embolization sessions.

CONCLUSION

Bronchial artery embolization for massive hemoptysis with Embosphere particles 700-900 µm in size is a safe and effective method with high technical and clinical success rates. Long-term results are excellent.

Bronchial arteries: anatomy, function, hypertrophy, and anomalies

The two main sources of blood supply to the lungs and their supporting structures are the pulmonary and bronchial arteries. The bronchial arteries account for 1% of the cardiac output but can be recruited to provide additional systemic circulation to the lungs in various acquired and congenital thoracic disorders. An understanding of bronchial artery anatomy and function is important in the identification of bronchial artery dilatation and anomalies and the formulation of an appropriate differential diagnosis. Visualization of dilated bronchial arteries at imaging should alert the radiologist to obstructive disorders that affect the pulmonary circulation and prompt the exclusion of diseases that produce or are associated with pulmonary artery obstruction, including chronic infectious and/or inflammatory processes, chronic thromboembolic disease, and congenital anomalies of the thorax (eg, proximal interruption of the pulmonary artery). Conotruncal abnormalities, such as pulmonary atresia with ventricular septal defect, are associated with systemic pulmonary supply provided by aortic branches known as major aortopulmonary collaterals, which originate in the region of the bronchial arteries. Bronchial artery malformation is a rare left-to-right or left-to-left shunt characterized by an anomalous connection between a bronchial artery and a pulmonary artery or a pulmonary vein, respectively. Bronchial artery interventions can be used successfully in the treatment of hemoptysis, with a low risk of adverse events. Multidetector computed tomography helps provide a vascular road map for the interventional radiologist before bronchial artery embolization.

Diagnosis and management of hemoptysis

Hemoptysis is the expectoration of blood that originates from the lower respiratory tract. It is usually a self-limiting event but in fewer than 5% of cases it may be massive, representing a life-threatening condition that warrants urgent investigations and treatment. This article aims to provide a comprehensive literature review on hemoptysis, analyzing its causes and pathophysiologic mechanisms, and providing details about anatomy and imaging of systemic bronchial and nonbronchial arteries responsible for hemoptysis. Strengths and limits of chest radiography, bronchoscopy, multidetector computed tomography (MDCT), MDCT angiography and digital subtraction angiography to assess the cause and lead the treatment of hemoptysis were reported, with particular emphasis on MDCT angiography. Treatment options for recurrent or massive hemoptysis were summarized, highlighting the predominant role of bronchial artery embolization. Finally, a guide was proposed for managing massive and nonmassive hemoptysis, according to the most recent medical literature.

A Surgical Case of Bronchial Artery Aneurysm Directory Connecting with Pulmonary Artery

We present a surgical case of bronchial artery aneurysm (BAA) connecting pulmonary artery accompanied with racemose hemangioma. This is a third surgical case report of BAA directly connecting pulmonary artery in the English literature. A 63-year-old female was found a BAA, 2 cm in diameter, connecting right A4 pulmonary artery. The patient underwent two attempts for embolization. However, due to extensive collaterals, there was persistent flow in the aneurysm. Standard lateral thoracotomy was performed. A BAA was located between A4 and A5 PA. A small branch of A4 PA was separated, and the small vessel connecting to the BAA could be ligated. A5 PA was separated similarly, however BAA was ruptured not to identify the other small vessel connecting to the BAA. After a clamp of the BAA, middle lobe lobectomy was performed. We removed the aneurysm with dilated bronchial artery connecting to the aneurysm. The postoperative course was uneventful.

Experimental studies in the bronchial circulation. Which is the ideal animal model?

BACKGROUND

The importance of the role of bronchial arteries is notable in modern days thoracic surgery. The significance of their anastomoses with adjusted structures has not yet been sufficiently rated, especially in cases of haemoptysis, heart-lung transplantations and treatment of aneurysms of the thoracic aorta. The need of a thorough study is more relevant than ever and appropriate laboratory animals are required.

METHODS

We review the literature in order to highlight the ideal experimental animal for the implementation of pilot programs relative to the bronchial circulation. A comparative analysis of the anatomy of the bronchial arterial system in humans along with these of pigs, dogs, rats, and birds, as being the most commonly used laboratory animals, is presented in details.

RESULTS

The pig has the advantage that the broncho-oesophageal artery usually originates from the aorta as a single vessel, which makes the recognition and dissection of the artery easy to perform. In dogs, there is significant anatomical variation of the origin of the bronchial arteries. In rats, bronchial artery coming from the aorta is a rare event while in birds the pattern of the bronchial artery tree is clearly different from the human analog.

CONCLUSIONS

The pig is anatomically and physiologically suited for experimental studies on the bronchial circulation. The suitable bronchial anatomy and physiology along with the undeniable usefulness of the pig in experimental research and the low maintenance cost make the pig the ideal model for experiments in bronchial circulation.

Imaging evaluation of hemoptysis in children

Hemoptysis is an uncommon but distressing symptom in children. It poses a diagnostic challenge as it is difficult to elicit a clear history and perform thorough physical examination in a child. The cause of hemoptysis in children can vary with the child's age. It can range from infection, milk protein allergy and congenital heart disease in early childhood, to vasculitis, bronchial tumor and bronchiectasis in older children. Acute lower respiratory tract infections are the most common cause of pediatric hemoptysis. The objective of imaging is to identify the source of bleeding, underlying primary cause, and serve as a roadmap for invasive procedures. Hemoptysis originates primarily from the bronchial arteries. The imaging modalities available for the diagnostic evaluation of hemoptysis include chest radiography, multi-detector computed tomography (MDCT), magnetic resonance imaging (MRI) and catheter angiography. Chest radiography is the initial screening tool. It can help in lateralizing the bleeding with high degree of accuracy and can detect several parenchymal and pleural abnormalities. However, it may be normal in up to 30% cases. MDCT is a rapid, non-invasive multiplanar imaging modality. It aids in evaluation of hemoptysis by depiction of underlying disease, assessment of consequences of hemorrhage and provides panoramic view of the thoracic vasculature. The various structures which need to be assessed carefully include the pulmonary parenchyma, tracheobronchial tree, pulmonary arteries, bronchial arteries and non-bronchial systemic arteries. Since the use of MDCT entails radiation exposure, optimal low dose protocols should be used so as to keep radiation dose as low as reasonably achievable. MRI and catheter angiography have limited application.

Safety of bronchial arterial embolization with n-butyl cyanoacrylate in a swine model

AIM: To compare the efficacy and safety of bronchial artery embolization (BAE) with n-butyl cyanoacrylate (NBCA) and gelatin sponge particles (GSPs).

METHODS: Six healthy female swine were divided into two groups to be treated with BAE using NBCA-lipiodol (NBCA-Lp) and using GSPs. The occlusive durability, the presence of embolic materials, the response of the vessel wall, and damage to the bronchial wall and pulmonary parenchyma were compared.

RESULTS: No animals experienced any major complication. Two days later, no recanalization of the bronchial artery was observed in the NBCA-Lp group, while partial recanalization was seen in the GSP group. Embolic materials were not found in the pulmonary artery or pulmonary vein. NBCA-Lp was present as a bubble-like space in bronchial branch arteries of 127-1240 μm, and GSPs as reticular amorphous substance of 107-853 μm. These arteries were in the adventitia outside the bronchial cartilage but not in the fine vessels inside the bronchial cartilage. No damage to the bronchial wall and pulmonary parenchyma was found in either group. Red cell thrombus, stripping of endothelial cells, and infiltration of inflammatory cells was observed in vessels embolized with NBCA-Lp or GSP.

CONCLUSION: NBCA embolization is more potent than GSP with regard to bronchial artery occlusion, and both materials were present in bronchial branch arteries ≥ 100 μm diameter.

Multi-detector row CT of hemoptysis

Hemoptysis is symptomatic of a potentially life-threatening condition and warrants urgent and comprehensive evaluation of the lung parenchyma, airways, and thoracic vasculature. Multi-detector row computed tomographic (CT) angiography is a very useful noninvasive imaging modality for initial assessment of hemoptysis. The combined use of thin-section axial scans and more complex reformatted images allows clear depiction of the origins and trajectories of abnormally dilated systemic arteries that may be the source of hemorrhage and that may require embolization. Conditions such as bronchiectasis, chronic bronchitis, lung malignancy, tuberculosis, and chronic fungal infection are some of the most common underlying causes of hemoptysis and are easily detected with CT. "Cryptogenic" hemoptysis is common among smokers and warrants subsequent follow-up imaging to exclude possible underlying malignancy. The bronchial arteries are the source of bleeding in most cases of hemoptysis. Contributions from the non-bronchial systemic arterial system represent an important cause of recurrent hemoptysis following apparently successful bronchial artery embolization. Vascular anomalies such as pulmonary arteriovenous malformations and bronchial artery aneurysms are other important causes of hemoptysis. Multi-detector row CT angiography permits noninvasive, rapid, and accurate assessment of the cause and consequences of hemorrhage into the airways and helps guide subsequent management.

Pulmonary neovascularity: a distinctive radiographic finding in Eisenmenger syndrome

BACKGROUND

We sought to characterize the distinctive pulmonary vascular abnormalities seen on chest radiographs and computed tomography (CT) scans in Eisenmenger syndrome.

METHODS AND RESULTS

Thoracic CT scans, chest radiographs, and clinical data were reviewed for 24 Eisenmenger syndrome patients subdivided into those with interatrial (pretricuspid) versus interventricular or great arterial (posttricuspid) communications and in 14 acyanotic patients with pulmonary arterial hypertension (PAH) and no congenital heart disease. CT scans were scored blindly by 2 thoracic radiologists for the presence and severity of small, tortuous, intrapulmonary vessels, termed "neovascularity," lobular ground-glass opacification, and systemic perihilar and intercostal vessels. Histopathologic lung sections from 5 patients with Eisenmenger syndrome and from 3 patients with acyanotic PAH were reviewed. Associations between clinical and imaging features were tested by ANOVA and chi2 tests. Kendall's rank-order coefficient and the Kruskal-Wallis test were used to test for significant differences in imaging features between Eisenmenger syndrome and acyanotic PAH. Neovascularity on chest radiographs was more common in Eisenmenger syndrome than acyanotic PAH, but differences were not significant. On CT, neovascularity, lobular ground-glass opacification, and hilar and intercostal systemic collaterals were more prevalent in Eisenmenger syndrome, with severity greater in posttricuspid communications. Three previously undescribed vascular lesions were identified histologically in Eisenmenger syndrome: malformed, dilated, muscular arteries within alveolar septa; congested capillaries within alveolar walls; and congested capillaries within the walls of medium-size, muscular pulmonary arteries. These lesions may correspond to the distinctive vascular abnormalities observed on chest radiographs and CT scans.

CONCLUSIONS

Distinctive vascular lesions on chest radiographs and CT scans in Eisenmenger syndrome appear to be correlated histologically with collateral vessels that develop more extensively with posttricuspid communications.

Effect of bronchial artery blood flow on cardiopulmonary bypass-induced lung injury

Cardiovascular surgery requiring cardiopulmonary bypass (CPB) is frequently complicated by postoperative lung injury. Bronchial artery (BA) blood flow has been hypothesized to attenuate this injury. The purpose of the present study was to determine the effect of BA blood flow on CPB-induced lung injury in anesthetized pigs. In eight pigs (BA ligated) the BA was ligated, whereas in six pigs (BA patent) the BA was identified but left intact. Warm (37°C) CPB was then performed in all pigs with complete occlusion of the pulmonary artery and deflated lungs to maximize lung injury. BA ligation significantly exacerbated nearly all aspects of pulmonary function beginning at 5 min post-CPB. At 25 min, BA-ligated pigs had a lower arterial Po2at a fraction of inspired oxygen of 1.0 (52 ± 5 vs. 312 ± 58 mmHg) and greater peak tracheal pressure (39 ± 6 vs. 15 ± 4 mmHg), pulmonary vascular resistance (11 ± 1 vs. 6 ± 1 mmHg·l–1·min), plasma TNF-α (1.2 ± 0.60 vs. 0.59 ± 0.092 ng/ml), extravascular lung water (11.7 ± 1.2 vs. 7.7 ± 0.5 ml/g blood-free dry weight), and pulmonary vascular protein permeability, as assessed by a decreased reflection coefficient for albumin (σalb; 0.53 ± 0.1 vs. 0.82 ± 0.05). There was a negative correlation ( R = 0.95, P < 0.001) between σalband the 25-min plasma TNF-α concentration. These results suggest that a severe decrease in BA blood flow during and after warm CPB causes increased pulmonary vascular permeability, edema formation, cytokine production, and severe arterial hypoxemia secondary to intrapulmonary shunt.

Development of systemic to pulmonary collateral arteries in premature infants

Infants with congenital heart disease and chronic lung disease are at risk for development of systemic-to-pulmonary collateral arteries (SPCA). This study characterizes associated clinical findings in 20 premature infants without CHD who were diagnosed as having SPCA with echocardiography. SPCA can occur in premature infants without chronic lung disease and may represent a transient phenomenon.

Development of the pharyngeal arch system related to the pulmonary and bronchial vessels in the avian embryo. With a concept on systemic-pulmonary collateral artery formation

BACKGROUND

The literature is ambiguous as to the question of the developmental background of systemic-pulmonary collateral arteries. These are found in combination with various congenital heart malformations such as pulmonary atresia. From a clinical point of view, it is of interest to know whether we are dealing with the persistence of transient embryological vessels such as ventral segmental arteries or parts of pharyngeal arch arteries or with the prenatal or postnatal recruitment of the bronchial vasculature that normally supplies the lung. This study of the embryology of the extrapulmonary and intrapulmonary vasculature aims at a better understanding of the variations in origin, course, branching pattern, and histology of collateral arteries.

METHODS AND RESULTS

Serial sections of quail embryos ranging between stage HH11 and stage HH28 were incubated with a monoclonal antibody (alpha MB1) against endothelial cells and their precursors. Additional series of chick embryos were injected with india ink to study the lumenized vascular patterns. A splanchnic plexus consisting of endothelial cells and precursors is present around the foregut before the lung buds develop. This plexus expands and gives rise to the pharyngeal arch arteries, the ventral pharyngeal veins, the pulmonary vessels, and the bronchial vessels, including the intrapulmonary vessel network. During two subsequent periods, the splanchnic plexus is transiently connected to the systemic arteries and veins. The bronchial arteries and veins develop in the second period from these transient vessels. The expansion and extension of the splanchnic plexus to many organs during the formation of the bronchial vessels explains the varying course and branching pattern of the bronchial vasculature.

CONCLUSIONS

These results show that we are not dealing with two or more individual vascular systems that contribute to the developing vessels of the lungs but with one vascular plexus that normally gives rise to the pulmonary and bronchial vasculature but has the potential to give rise to other systemic-pulmonary connections.

Endobronchial changes in chronic pulmonary venous hypertension

The bronchial venous system closely communicates with the pulmonary circulation. To assess the changes in the bronchial circulation in chronic pulmonary venous hypertension, fiberoptic bronchoscopy and right heart catheterization were performed in 31 patients with mitral stenosis. Nonpulsatile submucosal vessel dilatation, consistently seen in all patients and called the vessel dilatation score, was assessed visually by three independent bronchoscopists. The vessel dilatation score was correlated more closely with pulmonary artery wedge pressure (r = 0.687) (p less than 0.001) than to mean pulmonary artery pressure (r = 0.531) (p less than 0.01) and right atrial pressure (r = 0.178) (NS). The vessel dilatation score decreased after reduction of the left atrial load by surgery. These results suggest that the dilated vessels observed in patients with mitral stenosis are bronchial veins that are engorged secondary to increased blood flow via bronchopulmonary anastomoses.

Bronchopulmonary anastomotic and noncoronary collateral blood flow in humans during cardiopulmonary bypass

The sole source of blood returning to the left atrium during cardiopulmonary bypass, while the aorta is cross-clamped, is the bronchopulmonary anastomotic blood flow. In addition, there is noncoronary collateral blood flow which returns to the right atrium. Routinely, the bronchopulmonary anastomotic flow is drained from the left ventricle by a cannula and returned to the main circuitry via a cardiotomy reservoir. The noncoronary collateral flow may be vented similarly by introducing a cannula into the right atrium. Both the anastomotic and the noncoronary collateral flow can be measured with no further surgical intervention. We measured bronchopulmonary anastomotic flow in 40 patients undergoing coronary artery bypass surgery and the noncoronary collateral blood flow in 27 of these patients. Results from this study show that the bronchopulmonary anastomotic flow for the 40 patients was 140 +/- 182 ml/min (range 8 to 1,043 ml/min), representing 3.23 +/- 4.15 percent of the pump flow (equivalent to the cardiac output), and the noncoronary collateral flow in the 27 patients was 48 +/- 74 ml/min (range 0 to 261 ml/min), representing 1.11 +/- 1.67 percent of the pump flow.

Lung lipid metabolism and surface tension phenomena following pulmonary embolism

Images