Pulmonary Medicine

Congenital Pulmonary Syndromes (pulmonary artery anomalies, pulmonary artery sling, pulmonary artery agenesis, pulmonary artery hypogenesis, pulmonary artery supravalvular stenosis)

What every physician needs to know:

Congenital abnormalities of the pulmonary vasculature occur in both pulmonary arteries and veins. However, the pulmonary vasculature may be affected by other congenital thoracic vascular anomalies that primarily involve cardiac, aortic, or intrathoracic systemic venous structures, such as tetralogy of Fallot.

Many congenital abnormalities of pulmonary vasculature cause early symptoms during infancy and childhood, but others may not present until adulthood with delayed onset of symptoms or asymptomatic presentations as incidental findings on chest imaging studies.

The most common pulmonary arterial abnormalities are pulmonary artery sling and hypoplasia, agenesis, and stenosis of the supravalvular pulmonary artery. Childhood pulmonary artery anomalies often occur in association with other congenital defects or as defined syndromes, such as Williams, Alagille’s, Noonan’s, congenital rubella, cutis laxa, Ehlers-Danlos, and Silver’s. Isolated proximal obstruction of a pulmonary artery in an adult is a rare presentation de novo. Most patients are asymptomatic, but about 25 percent develop progressive dyspnea and pulmonary hypertension, which is often misdiagnosed as chronic thromboembolic disease.

Pulmonary venous abnormalities include total anomalous pulmonary venous return and partial anomalous pulmonary venous return, the latter of which includes four major categories (Type I, Type II, Type III, Mixed), depending on the point of drainage of anomalous veins.

Regarding pulmonary arterial anomalies, a pulmonary artery sling is a rare anomaly that develops when the left pulmonary artery derives from the right pulmonary artery and passes between the trachea and esophagus, causing compression of the trachea and/or esophagus. It most often presents in childhood but may rarely present as an isolated lesion in adults. Hypoplasia, agenesis, or stenosis of a pulmonary artery at the supravalvular level totally or partially obstruct blood flow to the affected lung, causing radiographic evidence of a small ipsilateral hilum with signs of hypertrophy of collateral circulation from bronchial arteries, intercostal arteries, coronary arteries, and/or a patent ductus arteriosus. These supravalvular abnormalities are rare conditions in the adult as de novo abnormalities so they are often unsuspected or misdiagnosed. Lesions may be diffuse and affect long segments of the artery or focal/multifocal with poststenotic dilatation. Symptomatic adults present with clinical features that simulate pulmonary hypertension or chronic pulmonary thromboembolic disease.

Anomalous pulmonary venous return is defined by the drainage of oxygenated blood from a pulmonary vein or veins that drain anomalously into the left brachiocephalic vein, the superior vena cava, the right atrium, the inferior vena cava, or the hepatic veins. If all four pulmonary veins drain aberrantly, the disorder, which is then called "total anomalous pulmonary venous return," results in a cyanotic condition with total mixing of systemic and venous blood and pulmonary venous blood at the level of the heart. Less than all four pulmonary veins with aberrant drainage is termed "partial anomalous pulmonary venous return" and is usually not a cyanotic condition. The anomalous drainage into the right heart or systemic circulation results in a left-to-right shunt that may or may not be hemodynamically significant, depending on the degree of aberrant blood flow.

Classification:

Pulmonary artery anomalies

Pulmonary artery sling

Pulmonary artery agenesis

Pulmonary artery hypogenesis

Pulmonary artery supravalvular stenosis

Some experts prefer the term “unilateral proximal interruption” of pulmonary arteries, rather than "agenesis" or "absence," because the portion of the vessel within the lung is usually present but is blocked from receiving flow because of proximal stenotic lesions.

Pulmonary venous anomalies

Total anomalous pulmonary venous return

Partial anomalous pulmonary venous return is divided into:

  • Type I (or Supracardiac), with blood draining into one of the innominate veins

  • Type II (or Intracardiac), with blood draining into the coronary sinus or directly into the right atrium

  • Type III (or Infracardiac/Infradiaphragmatic), with blood draining into portal or hepatic veins

  • Mixed, with a combination of sites for venous drainage

Are you sure your patient has a congenital pulmonary vascular anomaly?

Patients with congenital anomalies of the pulmonary vasculature present differently, depending on the nature of the underlying vascular abnormality.

Patients with pulmonary artery slings usually present in childhood with symptoms related to compression of the trachea and/or esophagus. Children with tracheal compression develop varying degrees of stridor, cough, or shortness of breath. The condition is frequently associated with coexisting central airway anomalies and acquired abnormalities that include tracheal rings, right upper lobe tracheal bronchus, and tracheomalacia. These abnormalities produce additional respiratory symptoms that can simulate recurrent bronchitis, pneumonia, aspiration, and tracheoesophageal fistula.

Patients who present in adulthood with pulmonary artery slings have an isolated vascular anomaly that may be noted on routine radiographic studies as a mediastinal mass, requiring further evaluation by CT or MRI imaging.

Patients with agenesis, hypogenesis, or stenosis of a pulmonary artery may present with respiratory and cardiac symptoms related to decreased blood flow to the lungs and right ventricular hypertrophy, or tricuspid regurgitation secondary to pulmonary hypertension and right heart failure. Isolated congenital pulmonary artery stenosis in children must be differentiated from other conditions associated with stenosis, which include congenital rubella, Williams syndrome, Noonan syndrome, Alagile syndrome, Ehlers-Danlos syndrome, LEOPARD syndrome, and cutis laxa.

In patients with pulmonary stenosis and increased right ventricular pressures, cardiac examination may demonstrate prominence of the jugular venous A wave, left para-sternal lift, prominent right ventricular systolic impulse, systolic ejection murmur loudest at the left upper sternal border, splitting of the second heart sound, right-sided fourth heart sound when right ventricular hypertrophy occurs, a decrescendo diastolic murmur if tricuspid insufficiency develops, and/or cyanosis if severe pulmonary hypertension activates a patent foramen ovale or atrial septal defect with a right-to-left shunt.

Total anomalous pulmonary venous return presents in infancy as a cyanotic heart disease because a patent foramen ovale or atrial septal defect with a right-to-left shunt must be present to allow systemic cardiac blood flow. In addition to cyanosis, tachypnea, and dyspnea, patients have physical findings of right ventricular heave, fixed splitting of S2, S3 gallop, systolic ejection murmur along the left upper sternal border, cardiomegaly, right axis deviation on ECG, Snowman sign (or “figure 8” configuration) on chest radiographs, and right ventricular hypertrophy.

Partial anomalous pulmonary venous return is usually well tolerated by children with minimal symptoms. Later in life, however, the mixing of oxygenated blood from the lungs with oxygen-poor blood from the systemic circulation reduces the effectiveness of cardiovascular performance and may eventually cause exertion-related dyspnea and/or atrial arrhythmias. If more than half of the pulmonary venous blood flow is drained anomalously, patients may develop right ventricular strain, pulmonary hypertension, and symptoms with abnormal physical findings similar to those observed in patients with total anomalous pulmonary venous return.

Beware: There are other diseases that can mimic congenital pulmonary vascular anomalies

Pulmonary arterial congenital abnormalities decrease blood flow to the lung and increase right ventricular afterload. Patients can develop right ventricular strain and simulate conditions associated with pulmonary hypertension, including acute and chronic pulmonary thromboembolic disease, idiopathic pulmonary arterial hypertension, and pulmonary hypertension associated with primary underlying conditions like collagen vascular diseases (e.g., scleroderma), valvular heart disease (e.g., mitral stenosis), left ventricular failure, pulmonary veno-occlusive disease, vasculitis (Behcet’s disease and Takayasu’s arteritis), mediastinal fibrosis, and congenital heart disease.

Pulmonary valvular and subvalvular stenosis may simulate supravalvular stenosis. Patients with post-stenotic dilatation that is due to supravalvular stenosis of the pulmonary artery resulting from pulmonary stenosis may simulate a hilar mass on chest radiographs. Pulmonary hypogenesis or agenesis creates the appearance of unilateral pulmonary oligemia, thereby simulating pulmonary embolism.

Partial anomalous pulmonary venous return often remains asymptomatic until adulthood, when symptoms of dyspnea on exertion and atrial fibrillation may simulate cardiac disease with congestive heart failure or acute coronary syndromes.

Why did the patient develop a congenital pulmonary vascular anomaly?

The congenital pulmonary vascular anomalies discussed in this chapter are defects that are inborn so they represent an abnormality in embryonic development rather than a true disease. They occur as a result of aberrant angiogenesis.

Patients who present in adulthood with isolated pulmonary artery anomalies have often had murmurs noted in childhood but only become symptomatic later in life. Therefore, it has been conjectured that small, asymptomatic stenotic lesions may progress slowly in a nonuniform pattern, causing areas of vascular obstruction.

Which individuals are at greatest risk of developing congenital pulmonary vascular abnormalities?

There are no risk profiles for patients who develop these congenital anomalies, although up to 2 percent of patients with pulmonary artery stenosis have family members with a similar abnormality.

What laboratory studies should you order to help make the diagnosis, and how should you interpret the results?

There are no laboratory tests to establish the diagnosis of a pulmonary vascular anomaly.

To exclude other conditions that mimic pulmonary artery anomalies presenting de novo in the adult, laboratory testing may be necessary to evaluate for vasculitis, thromboembolic disease, and collagen vascular diseases.

What imaging studies will be helpful in making or excluding the diagnosis of congenital pulmonary vascular anomalies?

Imaging studies are the cornerstone for evaluations of patients for pulmonary vascular anomalies and determining the specific lesion that is present.

Standard radiographs

In patients with pulmonary artery agenesis, hypogenesis, and severe stenosis, the ipsilateral lung and hilum appear smaller than normal with elevation of the diaphragm and shift of the mediastinum to the effected side. The contralateral lung is hyperinflated with evidence of herniation across the mediastinum to the smaller hemithorax. These abnormalities occur most commonly in the right lung as isolated abnormalities. Interruption of the left pulmonary artery is commonly associated with right aortic (tetralology of Falot) or cardiac anomalies, which are evident on the standard radiograph. Extensive collateral vessels that perfuse the lung from the bronchial arteries, intercostal arteries, internal mammary, subclavian, and /or coronary arteries may produce varied appearances of vascular densities, rib notching, and pleural thickening.

In asymptomatic adults with pulmonary artery slings, the chest radiograph may simulate a mediastinal mass, but the CT or MRI scans will confirm the presence of a vascular lesion and the correct diagnosis.

With pulmonary artery proximal interruption, however, the affected lung often remains as radiographically dense as the normal lung with evidence of peripheral pulmonary vasculature, which differentiates this condition from Swyer-James syndrome and other hypogenetic lung syndromes from pulmonary artery anomalies. In patients with hyperlucency of the affected lung, no air trapping occurs, which is a major discriminator from Swyer-James syndrome.

Most patients with pulmonary artery slings present in infancy because of associated tracheobronchial and cardiac abnormalities. In patients with isolated pulmonary vascular slings, very few will present as asymptomatic adults. The chest radiograph in these instances may demonstrate a mediastinal mass.

Patients with total anomalous pulmonary venous drainage have cardiomegaly that is due to right atrial and ventricular dilatation that occurs as a result of increased pulmonary vasculature resistance and increased cardiac blood flow. Pulmonary veins appear enlarged in the lung fields and close to the hilum. In patients with partial anomalous pulmonary venous return, who drain anomalous veins through a vertical vein into the left brachiocephalic vein, the vertical vein simulates a left-sided superior vena cava. Venous structures that drain into the innominate vein, combined with a persistent left superior vena cava, create a large supracardiac shadow that, combined with a normal cardiac shadow, produces a “snowman” appearance.

When the anomalous veins drain into the inferior vena cava, a “scimitar” sign appears with the anomalous vein, coursing along the right cardiac border in the right lower lung field. Patients with the “scimitar syndrome” do not have an associated atrial septal defect but often have an associated pulmonary sequestration and anomalous arterial supply to the lobe affected by the sequestration. If the anomalous pulmonary veins become obstructed, the chest radiograph may demonstrate radiographic evidence of pulmonary congestion.

What non-invasive pulmonary diagnostic studies will be helpful in making or excluding the diagnosis?

Echocardiography

For some patients with pulmonary arterial anomalies, two-dimensional and three-dimensional electrocardiography may allow narrowing of the pulmonary artery at the supravalvular level to be detected. It can also demonstrate right ventricular strain and hypertrophy patterns. Transesophageal echocardiography does not provide additional advantages.

For patients with anomalous pulmonary venous abnormalities, echochardiography can demonstrate an enlarged right ventricle and a small left atrium. In some patients it may also detect the abnormal venous vascular connections. Doppler evidence of pulmonary venous blood flow away from the heart establishes the presence of total anomalous pulmonary venous return. Doppler is also a sensitive technique for demonstrating a right-to-left shunt at the atrial level, which commonly occurs with pulmonary venous anomalies.

Electrocardiography

Depending on the extent of pulmonary vascular obstruction, patients with pulmonary artery anomalies may have varying degrees of electrocardiographic evidence of right ventricular hypertrophy or unusual electrical axes because of a shift of the mediastinum to the effected side.

The electrocardiogram in patients with anomalous pulmonary venous return who have increased right-sided cardiac pressures demonstrates right ventricular hypertrophy, usually characterized by a qR in V3, R, and V2. P waves are typically tall and peaked.

Magnetic resonance imaging and computerized tomography angiography

Multidetector row computerized tomography (MDCT) scanning provides clear imaging of pulmonary arteries to detect vascular anomalies, including supravalvular stenosis (Figure 1) (Figure 2) ( Figure 3). Advantages over pulmonary angiography include the ability to image the lung parenchyma, the airways, and the heart to detect associated abnormalities. The MDCT scan can demonstrate the mediastinal segment of a pulmonary artery that may be absent or that may terminate within 1 cm of its origin. Areas of stenosis or serrated thickening of a pulmonary branch may be detected, which represent anastomoses with collateral vessels. The bronchial branching pattern and pulmonary venous drainage remain normal in appearance. Trans-pleural collateral intercostal arteries, internal mammary arteries, subclavian arteries, and innominate arteries may cause peripheral parenchymal linear opacities perpendicular to the pleural surfaces.

Figure 1.

Supravalvular pulmonic stenosis. Narrowing of the pulmonary trunk (white arrows) and poststenotic dilatation of the left main pulmonary artery (LPA) are shown clearly in this sagittal maximum-intensity projection image. PA, pulmonary artery. (Image and legend reproduced with permission.)

Figure 2.

Supravalvular pulmonic stenosis. Narrowing of the pulmonary trunk (white arrows) and poststenotic dilatation of the left main pulmonary artery are shown clearly in this three-dimensional volume-rendered reconstruction from a frontal perspective. Ao, aorta; PA, pulmonary artery. (Image and legend reproduced with permission.)

Figure 3.

Supravalvular pulmonic stenosis. Narrowing of the pulmonary trunk and poststenotic dilatation of the left main pulmonary artery (LPA) are shown clearly in this three-dimensional volume-rendered reconstruction from a superior (C) perspective. Ao, aorta; PA, pulmonary artery. (Image and legend reproduced with permission.)

High-resolution two-dimensional and three-dimensional MR imaging with various modalities with or without contrast and angiographic techniques are all comprehensive multiprojection displays of anatomy for diagnosis and treatment planning.

MDCT readily identifies the vascular features of a pulmonary artery sling.

Both MRI and MDCT scanning are helpful in the assessment of patients with anomalous pulmonary venous return when echocardiographic views are limited technically (Figure 4) (Figure 5) ( Figure 6). Gradient-refocused gradient echo imaging (e.g., FIESTA) at the atrial level is especially useful for pulmonary venous return when used with MRI, and two-dimensional cine phase contrast can accurately identify and quantify shunt flow.

Figure 4.

Left upper lober partial anomalous pulmonary venous return. Axial maximum-intensity projection image shows an abnormal vessel to the left of the aortic arch - the vertical vein (arrow). Ao, aorta. (Image and legend reproduced with permission.)

Figure 5.

Left upper lober partial anomalous pulmonary venous return. An oblique axial maximum-intensity projection image shows the vertical vein (arrow) draining into the left brachiocephalic vein (asterisk). Asterisk indicates left brachiocephalic vein. (Image and legend reproduced with permission.)

Figure 6.

Left upper lober partial anomalous pulmonary venous return. Three-dimensional volume-rendered reconstruction depicts the left upper lobe pulmonary veins draining into the vertical vein (arrow) and depicts the entire course of the vertical vein. Asterisk indicates left brachiocephalic vein. Ao, aorta. (Image and legend reproduced with permission.)

What diagnostic procedures will be helpful in making or excluding the diagnosis?

Noninvasive studies often allow diagnosis of pulmonary artery anomalies in children. For adults who present de novo with isolated supravalvular pulmonary artery stenosis, cardiac angiography with measurements of cardiac and pulmonary hemodynamics is usually required to differentiate pulmonary stenosis from other conditions associated with pulmonary hypertension, such as chronic thromboembolic disease. Selective pulmonary angiography may demonstrate multiple areas of stenosis. If patients are considered for balloon angioplasty, intravascular ultrasound may allow characterization of the extent of luminal narrowing and the response to angioplasty.

In anomalous pulmonary vascular return, cardiac catheterization can demonstrate the presence of anomalous pulmonary veins during selective pulmonary arteriography or venography. For patients with total anomalous pulmonary venous return, demonstration at catheterization of similar levels of oxygen saturation of blood in both atria, both ventricles, and in the aorta establishes the presence of total blood mixing. A step up in oxygen saturation may be detected at the site of entry of anomalous pulmonary venous drainage.

What pathology/cytology/genetic studies will be helpful in making or excluding the diagnosis?

No pathology, cytology, or genetic studies are needed to make the diagnoses of pulmonary vascular anomalies.

If you decide the patient has congenital pulmonary vascular anomalies, how should the patient be managed?

Infants with pulmonary arterial slings undergo surgical correction early, which may be complicated by coexisting cardiac and tracheobronchial anomalies. Asymptomatic adults with slings noted on radiographs as incidental findings do not need surgical repair.

For adult patients with supravalvular pulmonary stenosis, various surgical procedures with patch techniques are available. Balloon angioplasty may provide a short-term decrease in right ventricular hypertension and relieve symptoms of dyspnea and fatigue. Some centers perform stenting for pulmonary artery stenosis. Various vascular surgical reconstruction and conduit placement procedures are also performed in selected patients. Adults with central pulmonary artery hypoplasia and patients with supravalvular pulmonary stenosis in association with other cardiac anomalies require careful assessment for management by an expert in congenital heart disease. Patients who do not respond to angioplasty may be considered for organ transplantation.

Children with total anomalous pulmonary venous return require surgical redirection within the first month of life. Partial pulmonary venous return may be asymptomatic, which allows expectant management. Various surgical procedures are available for patients with extensive anomalous partial pulmonary venous return, such as may occur in the scimitar syndrome in patients with significant left to right shunting and pulmonary hypertension.

What is the prognosis for patients managed in the recommended ways?

The prognosis of patients depends on the extent of the vascular abnormalities, the presence of associated congenital abnormalities, the development of right-to-left shunts, and the presence of pulmonary hypertension.

Adult patients with pulmonary artery anomalies may be asymptomatic if supravalvular stenosis is minimal (but present with dyspnea and evidence of pulmonary hypertension) if the stenosis is severe or progressive. Adults with pulmonary artery hypogenesis or agenesis may be asymptomatic and may not require therapy. For symptomatic patients with pulmonary artery stenosis, balloon angioplasty may produce symptomatic benefit, which is typically transient, eventually requiring other interventions. Surgical patch techniques usually provide good outcomes, although reoperation may be necessary, especially for patients who have associated pulmonary valvular stenosis.

Total anomalous pulmonary venous return requires surgical correction in childhood with a subsequent clinical course that is dependent on the success of the original procedure and the degree of associated cardiac congenital abnormalities. Patients with partial anomalous pulmonary venous return may remain asymptomatic unless aberrant pulmonary venous become obstructed, extensive left to right shunting develops, or pulmonary hypertension occurs, in which case dyspnea and hypoxia may occur. Patients who require surgical correction usually follow an excellent clinical course, although rare obstruction/stenosis of the reimplanted vein may occur. Pulmonary hypertension and arrhythmias may also occur, requiring patients to undergo follow-up by a cardiologist over the remainder of their lives. Children who require surgery for scimitar syndrome have a higher rate of postoperative pulmonary venous obstruction and abnormally diminished perfusion of the right lung.

What other considerations exist for patients with congenital pulmonary vascular anomalies?

Patients with congenital pulmonary vascular abnormalities remain at risk for endovascular infections. Patients with pulmonary artery abnormalities with extensive collateral vessel formation may develop hemoptysis if collateral vessels rupture. Patients with anomalous pulmonary venous return may develop dyspnea and hypoxia if vessels become thrombosed. During critical illness, patients may undergo placement of a central venous catheter, which may traverse the aberrant pulmonary veins, thereby confusing interpretation of data and risking vascular thrombosis.

What’s the evidence?

Mullen, JC, Waskiewich, K, Bhargava, R, Bentley, MJ. "Bilateral partial anomalous pulmonary venous return". Can J Cardiol. vol. 13. 1997. pp. 567-9.

The article presents two case reports of bilateral anomalous pulmonary venous return with illustrative imagine studies.

Broy, C, Bennett, S. "Partial anomalous pulmonary venous return". Mil Med. vol. 173. 2008. pp. 523-4.

This case report presents a unique manifestation of partial anomalaous pulmonary venous return that presented on chest radiographs as a pulmonary mass.

Ramseyer, L, Mansfield, W, Simon, W. "The scimitar syndrome: demonstration with magnetic resonance imaging". J Okla State Med Assoc. vol. 89. 1996. pp. 324-5.

The authors present a case of scimitar syndrome with characteristic MRI findings.

Tighe, DA, Thomas, NV, Hafer, JG. "Diagnosis of partial anomalous pulmonary venous connection with intact interatrial septum by echocardiography". Echocardiography. vol. 15. 1998. pp. 405-408.

This case study presents the complementary use of transthoracic echocardiography and transesophageal echocardiography in diagnosing partial anomalous pulmonary venous connections.

Kreutzer, J, Landzberg, MJ, Preminger, TJ. "Isolated peripheral pulmonary artery stenoses in the adult.". Circulation. vol. 93. 1996. pp. 1417-23.

The authors present a case of isolated peripheral pulmonary artery stenosis that simulated pulmonary thromobembolic disease.

Maldonado, JA, Henry, T, Gutierrez, FR. "Congenital thoracic vascular anomalies". Radiol Clin N Am. vol. 48. 2010. pp. 85-115.

A comprehensive review of imaging modalities for patients with thoracic vascular anomalies with superbly reproduced images.

Hellinger, JC, Daubert, M, Lee, EY. "Congenital thoracic vascular anomalies: evaluation with state-of-the-art MR imaging and MDCT.". Radiol Clin N Am. vol. 49. 2011. pp. 969-96.

Excellent review of imaging features using MR and MDCT for patients with a variety of congenital vascular abnormalities. The reproduced images are outstanding and state-of-the-art.

Alsoufi, B, Cai, S, Van Arsdell, GS. "Outcomes after surgical treatment of children with partial anomalous pulmonary venous connection.". An Thorac Surg. vol. 84. 2007. pp. 2020-6.

Review of the experience at the University of Toronto of surgical correction in children with partial anomalous pulmonary venous connections.

Korkmaz, AA, Yildiz, CE, Onan, B, Guden, M, Cetin, G, Babaoglu, K. "Scimitar syndrome: a complex form of anomalous pulmonary venous return". J Card Surg.. vol. 26. 2011. pp. 529-34.

The authors review the diagnostic features, clinical management, and surgical strategy for patients with scimitar syndrome.

Johri, S, Dunnington, GH. "A 61-year-old woman with exertional dyspnea and right-sided heart enlargement". Chest. vol. 139. 2011. pp. 702-3.

The authors present a teaching case of partial anomalous pulmonary venous connection and cover a broad range of issues.
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