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Cardiac imaging in common arterial trunk
Progress in Pediatric Cardiology 15 (2002) 41–51
Cardiac imaging in common arterial trunk Shi-Joon Yooa,*, Yang Min Kima, Eun Jung Baeb, Seong Ho Kimb, Jung Yeon Choic, In Sook Parkd, Heung Jae Leee a
Department of Radiology, Sejong Heart Institute, Puchon, South Korea Department of Pediatrics, Sejong Heart Institute, Puchon, South Korea c Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, South Korea d Department of Pediatrics, Asan Medical Center, University of Ulsan, Seoul, South Korea e Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University, Seoul, South Korea b
Abstract The diagnosis of common arterial trunk (truncus arteriosus communis) is suspected when the chest radiogram shows a combination of cardiomegaly with oval configuration, increased pulmonary vascularity, narrow superior mediastinum, concave pulmonary arterial segment and right aortic arch in a patient with cyanosis and cardiac murmur. In most cases, echocardiography can provide complete morphological information of common arterial trunk and its associated lesions, although magnetic resonance imaging can provide more objective images with clearer visualization of the adjacent mediastinal structures including thymus. Cardiac catheterization for calculation of pulmonary vascular resistance should be performed for patients older than 3 months. When catheterization is performed, angiograms are obtained for a better understanding of the pathology. The ventricular septal defect and overriding common arterial trunk are best shown in long axis view. The dominant vessel arising from the common arterial trunk is the aorta in the majority of cases. When the ascending aorta is smaller than the pulmonary artery, associated interruption of the aortic arch should be suspected. The origin of the pulmonary artery from the common arterial trunk can be seen in right and left anterior oblique views. Preferred echocardiographic views for evaluation of the pulmonary arterial anatomy are high-parasternal and suprasternal views. Truncus arteriosus can be diagnosed in the fetus by using high-resolution sonography. For fetal screening of common arterial trunk, a three-vessel view is very helpful. It is an orthogonal transverse view of the fetal upper mediastinum where the main pulmonary artery, ascending aorta and superior vena cava are arranged in a line. When there are only two vessels in the three-vessel view, common arterial trunk is suspected. Once the diagnosis of common arterial trunk is made in the fetus, fluorescent in situ hybridization (FISH) should be performed to exclude del 22(q11) or CATCH 22 syndrome. 䊚 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Common arterial trunk; Truncus arteriosus; Chest radiography; Echocardiography; Angiography; Magnetic resonance imaging
1. Introduction Common arterial trunk, which is also called truncus arteriosus, persistent truncus arteriosus or truncus arteriosus communis, refers to a condition in which a single arterial trunk arises from the heart through a single arterial valve and gives rise to the aorta, one or both pulmonary arteries, and coronary arteries w1–5x. When a single arterial trunk arises from the heart, but the pulmonary arteries to both lungs arise from the descend*Corresponding author. Department of Diagnostic Imaging, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada. Tel.: q1-416-813-6037; fax: q1-416-813-7591. E-mail address: [email protected] (S.-J. Yoo).
ing aorta or the branches of the aortic arch (Collett and Edwards Type IV truncus w2x), it is usually considered as a variant of tetralogy of Fallot with pulmonary atresia w3–5x. By using this definition, the hemitruncus in which one pulmonary artery arises from the ascending aorta and the other from the main pulmonary artery, is a misnomer because two discrete arterial trunks arise from the heart through two separate arterial valves. Various clinical and pathological features are described in the other papers in this issue. In this paper, we will discuss how the patients with common arterial trunk present themselves in their initial chest radiograms, and how their pathological features of clinical and surgical importance should be analyzed using echocardiography, magnetic resonance imaging and angiography.
1058-9813/02/$ - see front matter 䊚 2002 Elsevier Science Ireland Ltd. All rights reserved. PII: S 1 0 5 8 - 9 8 1 3 Ž 0 2 . 0 0 0 0 7 - 3
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2. Chest radiography
Fig. 1. Frontal chest radiogram from a cyanotic newborn shows marked cardiomegaly with a biventricular enlargement pattern and increased pulmonary vascularity.
As in other cardiac problems, the initial approach to the diagnosis of common arterial trunk includes taking chest radiograms as well as assessment of the patient’s symptoms and signs. The diagnosis of common arterial trunk is suspected when the chest radiogram shows cardiomegaly and increased vascularity in a patient with cyanosis and cardiac murmur (Figs. 1–3) w6x. The combination of cyanosis, cardiomegaly and increased pulmonary vascularity is also seen in patients with total anomalous pulmonary venous connection, tetralogy of Fallot with pulmonary atresia and large aortopulmonary collateral arteries, complete or corrected transposition of the great arteries or its variants without pulmonary stenosis, and various forms of univentricular atrioventricular connections without pulmonary stenosis. In common arterial trunk, cardiomegaly is usually due to biventricular and left atrial enlargement w6–9x. The cardiac configuration is commonly oval as in complete transposition of the great arteries and pulmonary atresia with intact ventricular septum (Figs. 2 and 3). The oval cardiac configuration in these conditions is produced by combination of biventricular enlargement, and absence
Fig. 2. (a) Frontal chest radiogram from a cyanotic newborn with hypocalcemia shows moderate cardiomegaly with oval configuration and increased pulmonary vascularity. The pulmonary conus is not prominent, but the right hilum is rather high. The superior mediastinum is narrow due to thymic hypoplasia. (b) and (c). Coronal and axial T1-weighted magnetic resonance images show a hypoplastic thymus (T). The main pulmonary artery (P) arises from the left wall of the common arterial trunk (Tr). Asascending aorta.
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Fig. 3. (a) Frontal chest radiogram shows moderate cardiomegaly and increased pulmonary vascularity. Note some bulging of left upper mediastinum (arrows) and straight left upper heart border (arrowheads). (b) Coronal T1-weighted magnetic resonance image shows that the thymus (T) forms the left upper mediastinal border masking the narrow vascular pedicle.
or hypoplasia of the right ventricular outflow tract that forms a bulk in the left upper corner of the ventricular mass below the left atrial appendage in normal individuals. In the common arterial trunk, the left upper heart border tends to be straight (Fig. 3) w7–9x. The heart may also show a right ventricular enlargement pattern in some cases. The superior mediastinum tends to be narrow, especially when the right and left pulmonary arteries arise directly from the posterior wall of the common arterial trunk without intervening main pul-
monary artery. Narrow superior mediastinum may be also due to regression of thymus due to a stressful patient’s condition, or due to actual hypoplasia or aplasia in association with DiGeorge syndrome (Fig. 2). The pulmonary arterial segment of the left heart border is usually concave as in tetralogy of Fallot with or without pulmonary atresia. When the main pulmonary artery arises from the left wall of the common arterial trunk (Collett and Edwards Type I truncus), however, the pulmonary arterial segment may be convex (Fig. 4).
Fig. 4. (a) Scout cineradiogram for truncal angiography in (b) shows that the superior mediastinum is wide and the pulmonary conus segment is full. (b) Truncal angiogram in frontal projection shows that the left pulmonary artery (LPA) arising from the main pulmonary arterial segment is responsible for fullness of the left upper mediastinum. Asascending aorta.
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Fig. 5. Frontal chest radiogram shows moderate cardiomegaly. There is a right aortic arch forming a vertical paravertebral shadow (arrows) on the right side.
Either or both of the left or right pulmonary arteries may arise at a higher level than normal and can be seen as a discrete structure (Fig. 2). The aortic arch is commonly high-arched and rather prominent. Right aortic arch is present in 25–50% (Fig. 5) w3–11x. The pulmonary vascularity is markedly increased in most cases (Figs. 1–3). The hypervascular lungs are commonly associated with segmental atelectasis, hyper-
Fig. 7. Left ventriculogram in long axial oblique view shows a large ventricular septal defect (D). A single arterial trunk (Tr) arises from both ventricles and bifurcates into the aorta (A) and the pulmonary artery (P). LVsleft ventricle, RVsright ventricle.
aeration and pneumonia (Fig. 6). Paradoxically, when the pulmonary vascularity is normal or only slightly increased and the lungs are clear, development of significant pulmonary vascular obstructive disease should be suspected, especially when the patient is old. Rarely, the pulmonary vascularity is decreased because of underdevelopment of the pulmonary trunk and branch pulmonary arteries. The pulmonary vascularity of the right and left lungs as well as the lung volume may not be equal when a pulmonary artery is hypoplastic or absent w9 x . To summarize the chest radiographic findings, a combination of cardiomegaly with oval configuration, increased pulmonary vascularity, narrow upper mediastinum, concave pulmonary arterial segment and right aortic arch in a cyanotic patient strongly suggests the diagnosis of common arterial trunk. 3. Echocardiography, magnetic resonance imaging and angiography
Fig. 6. Frontal chest radiogram shows marked cardiomegaly and increased pulmonary vascularity. Pneumonia with air-bronchograms is evident in the right upper lung. Multiple areas of segmental atelectasis are seen in both lungs.
Echocardiography can provide complete morphological information of common arterial trunk and its associated lesions in most cases, although magnetic resonance imaging can provide objective images with clearer visualization of the adjacent mediastinal structures w7,12–15x. Magnetic resonance imaging is useful when the overinflated lungs interfere with the echocardiographic evaluation w7,15x. When DiGeorge syndrome
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Fig. 8. (a) T1-weighted magnetic resonance image in long axis view shows a large ventricular septal defect (D). A single arterial trunk (Tr) arises from both ventricles and bifurcates into the aorta (A) and the pulmonary artery (P). (b) Subcostal long axis echocardiogram shows a lumpy and dysplastic truncal valve (arrows). The valve was both stenotic and regurgitant. (c) Right ventriculogram in left anterior oblique view shows crossed pulmonary artery (arrows). Because of crossing of pulmonary arteries, the right pulmonary artery (R) is seen below the left pulmonary artery (L) in long-axis magnetic resonance image shown in (a). LVsleft ventricle, RVsright ventricle.
is suspected, magnetic resonance imaging may be particularly useful as it clearly defines the status of the thymus (Fig. 2). Cardiac catheterization should be performed for calculation of pulmonary vascular resistance in patients older than 3 months. When catheterization is performed, angiograms are also obtained as they provide a better overview of the pathology and can sometimes demonstrate unexpected associated lesions w7,9,16–19x. However, angiography should not be performed when significant pulmonary vascular obstructive disease is suspected. Whatever the imaging modality is, the basic pathological features of the common arterial trunk can be best shown in the long axis images. The ventricular septal defect is typically large and occupies the region immediately below the overriding common arterial valve in
the majority of cases (Figs. 7 and 8a and Fig. 9). The findings seen in the long axis images are similar to those seen in patients of tetralogy of Fallot with or without pulmonary atresia. More frequently, the lower border of the ventricular septal defect is not in direct contact with the membranous septum, the truncal valve being separated from the tricuspid valve by an intervening muscular rim w4,9,16,18x. This muscular rim is formed by fusion of the ventriculo-infundibular fold and the posterior limb of the trabecula septomarginalis. It can be well outlined by right ventriculography in right anterior oblique view or sectional imaging in an equivalent view (Fig. 10). Less frequently, the lower border of the defect is in direct contact with the membranous septum, and thus the defect is a perimembranous type. In this occasion,
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Fig. 9. Parasternal long axis echocardiogram shows a ventricular septal defect (D) below the common arterial trunk (Tr). LVsleft ventricle, RVsright ventricle.
the truncal valve is in direct continuity with the tricuspid valve (Fig. 11). Rarely, the ventricular septal defect is restrictive or not present w3,5,20–23x. In most cases, the truncal valve is in fibrous continuity with the mitral valve w9x. The common arterial trunk usually arises from both ventricles through an overriding truncal valve (Figs. 7 and 8a). It often arises predominantly or exclusively
Fig. 11. So-called en-face magnetic resonance image shows a cutthrough section of the ventricular septum containing the defect (D). Notice that the truncal valve is in direct contact (arrow) with the tricuspid valve without intervening muscular rim. Thus, the defect is a perimembranous type. Trscommon arterial trunk.
from the right and less frequently from the left ventricle (Fig. 12) w10x. The number of truncal valve cusps can be best assessed by echocardiography in the short axis plane of the valve. The truncal valve is frequently
Fig. 10. (a) Right ventriculogram in elongated right anterior oblique view shows that the truncal valve is separated from the tricuspid valve by an intervening muscular rim (asterisks). It indicates that the ventricular septal defect is a non-perimembranous type. The right (R) and left (L) pulmonary arteries arise directly from the common arterial trunk (Tr). (b) Cine magnetic resonance image in semicoronal view shows comparable but clearer anatomy of pulmonary arterial origins. Asascending aorta, RAsright atrium, and RVsright ventricle.
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Fig. 12. (a) T1-weighted magnetic resonance image in four-chamber view shows a large perimembranous ventricular septal defect (D) in the inlet septum. (b) Magnetic resonance image in steep left anterior oblique view shows that the common arterial trunk (Tr) arises completely from the right ventricle with a long muscular conus. The truncal valve is remote from the ventricular septal defect. Asaorta, LAsleft atrium, LVs left ventricle, Pspulmonary artery, RAsright atrium, and RVsright ventricle.
thickened or dysplastic w10x. It is often regurgitant and occasionally stenotic (Fig. 8b) w9x. The morphology and function of the truncal valve can be assessed by twodimensional and Doppler echocardiography, as well as by angiography in long axis view.
The dominant vessel arising from the common arterial trunk is the aorta in the majority of cases. However, the ascending aorta is smaller than the pulmonary artery when there is interruption of the aortic arch (Fig. 13) w9,16,17,19,24x. This condition may be potentially con-
Fig. 13. (a) Trucal angiogram in left anterior oblique view shows that the common arterial trunk (Tr) bifurcates into the large main pulmonary artery (P) and the small ascending aorta (A). The pulmonary artery is continuous with the descending aorta (a) through a narrow ductus arteriosus (pda). (b) Late frame of truncal angiogram in frontal view shows that the aortic arch is interrupted between the origins of the left common carotid (LCA) and left subclavian (LSA) arteries. RIAsright innominate artery.
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Fig. 14. Suprasternal short axis echocardiogram shows the origins of the right (R) and left (L) pulmonary arteries from the posterior wall of the common arterial trunk (Tr) without intervening main pulmonary arterial segment.
Fig. 16. Truncal angiogram in lateral view shows that the origin of the left pulmonary artery (L) from the common arterial trunk (Tr) is much higher than that of the right (R).
fused with an aortopulmonary septal defect w17,24x. When there is interrupted aortic arch, the common arterial trunk tends to arise predominantly from the right ventricle w4,10x.
Fig. 15. Truncal angiogram in frontal view shows that both right (R) and left (L) pulmonary arteries arise more distally from the common arterial trunk (Tr).
Fig. 17. Aortogram in frontal view shows so-called Collett–Edwards type IV truncus. Each lung is supplied by a branch from the descending aorta. This condition is now considered a variant of tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral arteries. In most cases with pulmonary atresia, each lung is supplied by more than one collateral arteries.
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Fig. 18. Normal three-vessel view at fetal echocardiography. It is an orthogonal transverse view of the upper mediastinum. Oblique section of the main pulmonary artery (P), and cross-sections of the ascending aorta (A) and superior vena cava (V) are aligned in a straight line and sized in decreasing order. This view facilitates the diagnosis of a common arterial trunk as well as the anomalies of the ventricular outflow tracts, great arteries and superior vena cava in the fetus: as descending aorta; dsductus arteriosus; ltsleft; rtsright; Ssspine; and Tstrachea.
The origin of the pulmonary artery from the common arterial trunk can be seen in the right and left anterior oblique angiograms, or equivalent sectional images. When there is a main pulmonary arterial segment, it usually arises from the left wall of the common trunk (Fig. 2b and Fig. 4b). When there is no main pulmonary arterial segment, the right and left pulmonary arteries
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usually arise from the posterior wall of the common trunk (Figs. 10 and 14). In rare occasions, they may arise more distally from the common arterial trunk (Fig. 15), or one pulmonary artery may have more distal origin from the common arterial trunk than the other (Fig. 16) w18x. The length of the main pulmonary artery when present can be best defined by sectional imaging in the sagittal plane or angiography in left anterior oblique view with some cranial angulation w17x. Preferred echocardiographic views for the evaluation of the pulmonary arterial anatomy are high-parasternal and suprasternal views (Fig. 14) w12,14x. Magnetic resonance images can be obtained along the long axis of the pulmonary artery, facilitating clear delineation of the surgical anatomy (Fig. 10b). Rarely, the right and left pulmonary arteries cross each other especially when there is interruption of the aortic arch (Fig. 8) w10,25,26x. Crossed pulmonary artery should be suspected by echocardiography when normal bifurcation of the branch pulmonary arteries is not recognized and an anomalous pulmonary artery, which is the right pulmonary artery is seen beneath the left pulmonary artery (Fig. 8a,c) w26x. Rarely, the right or left pulmonary artery is absent or interrupted. On this occasion, pulmonary vein wedge angiography or preferentially white blood pool magnetic resonance imaging should be performed. Collett and Edwards Type IV truncus is usually considered as a variant of pulmonary atresia with ventricular septal defect, in which each lung is almost always supplied by multiple branches from the descending aorta or the branches of the aortic arch with few exceptions (Fig. 17) w3–5x. The pulmonary arteries are usually engorged and frequently tortuous. When the pulmonary vascular obstructive disease develops, the pulmonary arteries
Fig. 19. (a) Three-vessel view from a fetus with common arterial trunk shows only two vessels, the common arterial trunk (Tr) and superior vena cava (V). A similar three-vessel view may be seen in the tetralogy of Fallot with pulmonary atresia. (b) Oblique view of the common arterial trunk shows that it bifurcates into the ascending aorta (A) and the main pulmonary artery (P). asdescending aorta; Lsleft pulmonary artery; ltsleft; Rsright pulmonary artery; RAsright atrium; rtsright; RVsright ventricle; and Ssspine.
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Fig. 20. (a) Three-vessel view from another fetus shows only two vessels. The main pulmonary artery (P) arises from the left lateral wall of the common arterial trunk (Tr). The descending aorta (a) is seen on the right anterior aspect of the spine (S) as there was a right aortic arch. (b) Ventricular outflow tract view shows a large ventricular septal defect (D). The common arterial trunk arises exclusively from the left ventricle (LV), which is rare. LsIeft pulmonary artery, LTsleft, Rsright pulmonary artery, RTsright, and RVsright ventricle.
taper down abruptly, and the peripheral branches become obliterated, giving rise to an appearance of a pruned tree. With advanced disease, the background haze of capillary staining on pulmonary arterial wedge injection is reduced and inhomogeneous. The pulmonary circulation time tends to be prolonged. The aortic arch is often high-arched. As discussed, right aortic arch is common (Fig. 5) w3–11x. When there is a right aortic arch, the branching pattern is usually mirror-imaged. Anomalous origin of the right or left subclavian artery may be associated in a minority of cases w11,16x. Very rarely, the aorta is double-arched. The aortic arch is interrupted in up to 20% of cases w3,5,10,11,24x. When interrupted, it is usually after the origin of the left common carotid artery. This is in contrast to an aortopulmonary septal defect that is found usually with interruption distal to the origin of the left subclavian artery w24x. The ductus arteriosus is an essential pathway when the aortic arch or proximal left pulmonary artery is interrupted, while the ductus is usually absent when the aortic arch is patent (Fig. 13) w3,5,11,27x. There is considerable variation in the origins of the coronary arteries w4,9,10,28,29x. High take-off of one or both coronary arteries from the truncus or pulmonary artery is common. A single coronary artery is also common. Usually, the sinus located posteriorly or right laterally does not give rise to a coronary artery.
depend much on a so-called ‘three-vessel view’ for the diagnosis of congenital heart diseases affecting the ventricular outflow tracts andyor great arteries (Fig. 18) w30,31x. A three-vessel view is an orthogonal transverse view of the fetal upper mediastinum, in which the oblique section of the main pulmonary artery and the cross-sections of the ascending aorta and superior vena cava are arranged in a straight line and sized in decreasing order. It may be obtained simply by moving the sonographic transducer cranially along the fetal long axis from the well-known four-chamber plane. The diagnosis of a common arterial trunk is suspected when only two vessels are identified in the three-vessel view, although pulmonary atresia with absent or diminutive main pulmonary artery should be included in the differential diagnosis (Figs. 19 and 20). The diagnosis of a common arterial trunk may be entertained when the ventricular outflow tract view demonstrates a ventricular septal defect and single arterial trunk, which gives rise to the pulmonary artery or arteries and continues as the aortic arch. Once the diagnosis of common arterial trunk is made by fetal echocardiography, chromosomal study with fluorescent in situ hybridization (FISH) analysis should be performed to exclude deletion of 22(q11) or CATCH 22 syndrome w32x. The status of thymus can also be evaluated using ultrasound. The prenatal diagnosis of common arterial trunk enables initiation of appropriate treatment immediately after birth when the parents continue their pregnancy.
4. Fetal echocardiography References Typical anatomical features of common arterial trunk can be demonstrated by using high-resolution sonography. However, it is often difficult to reliably demonstrate the small pulmonary arteries arising from the common arterial trunk, especially in early gestational period. We
w1x Lev M, Saphir O. Truncus arteriosus communis persistens. J Pediatr 1942;20:74 –88. w2x Collett RW, Edwards JE. Persistent truncus arteriosus: a classification according to anatomic types. Surg Clin North Am 1949;29:1245 –1270.
S.-J. Yoo et al. / Progress in Pediatric Cardiology 15 (2002) 41–51 w3x Van Praagh R, Van Praagh S. The anatomy of common aorticopulmonary trunk (truncus arteriosus communis) and its embryologi implications: a study of 57 necropsy cases. Am J Cardiol 1965;16:406 –425. w4x Crupi G-C, Macartney FJ, Anderson RH. Persistent truncus arteriosus. A study of 66 autopsy cases with special reference to definition and morphogenesis. Am J Cardiol 1977;40:569 – 578. w5x Van Praagh R. Truncus arteriosus: what is it really and how should it be classified. Eur J Cardio-Thorac Surg 1987;1:65 – 70. w6x Swischuk LE, Sapire DW. Basic imaging in congenital heart disease. Baltimore: Williams and Wilkins; 1986. p. 115 –139. w7x Elliott LP, Jaffe RB, White RD. Truncus arteriosus. In: Elliott LP, editor. Cardiac imaging in infants, children and adults. Philadelphia: JB Lippincott Co; 1991. p. 693 –706. w8x Victoria BE, Elliott LP. The roentgenologic findings and approach to persistent truncus arteriosus in infancy. Am J Roentgenol 1968;104:440 –451. w9x Calder L, Van Praagh R, Van Praagh S, et al. Truncus arteriosus communis. Clinical, angiocardiographic, and pathologic findings in 100 patients. Am Heart J 1976;92:23 –38. w10x Butto F, Lucas RV, Edwards JE. Persistent truncus arteriosus: pathologic anatomy in 54 cases. Pediatr Cardiol 1986;7:95 – 101. w11x Gerlis LM, MacGregor CCd’A, Ho SY. An anatomical study of 110 cases with deficiency of the aorticopulmonary septum with emphasis on the role of the arterial duct. Cardiol Young 1992;2:342 –352. w12x Hagler DJ, Tajik AJ, Seward JB, Mair DD, Ritter DG. Wideangle two-dimensional echocardiographic profiles of conotruncal abnormalities. Mayo Clin Proc 1980;55:73 –82. w13x Houston AB, Gregory NL, Murtogh E, Coleman EN. Twodimensional echocardiography in infants with persistent truncus arteriosus. Br Heart J 1981;46:492 –497. w14x Rice MJ, Seward JB, Hagler DJ, Mair DD, Tajik AL. Definitive diagnosis of truncus arteriosus by two-dimensional echocardiography. Mayo Clin Proc 1982;57:476 –481. w15x Donnelly LF, Higgins CB. MR imaging of conotruncal abnormalities. Am J Roentgenol 1996;166:925 –928. w16x Ceballos R, Soto B, Kirklin JW, Bargeron LM. Truncus arteriosus. An anatomical-angiographic study. Br Heart J 1983;49:589 –599. w17x Yoshizato T, Julstrud PR. Truncus arteriosus revisited: an angiographic demonstration. Pediatr Cardiol 1990;11:36 –40. w18x Yoo S-J, Choi Y-H. Truncus arteriosus. Angiocardiograms in congenital heart disease. New York: Oxford University Press; 1991. p. 55 –62. w19x Freedom RM, Mawson JB, Yoo S-J, Benson LN. Truncus carteriosus or common arterial trunk. Congenital heart disease.
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Textbook of angiocardiography. New York: Futura Publishing Co; 1997. p. 219 –242. Carr I, Bharati S, Kusnoor VS, Lev M. Truncus arteriosus communis with intact ventricular septum. Br Heart J 1979;42:97 –102. Murdison KA, McLean DA, Carpenter B, Duncan WJ. Truncus arteriosus communis associated with mitral valve and left ventricular hypoplasia without ventricular septal defect: unique combination. Pediatr Cardiol 1996;17:322 –326. McElhinney DB, Reddy M, Brook MM, Hanley FL. Repair of truncus arteriosus with intact ventricular septum (Van Praagh type B2) in a neonate. J Thorac Cardiovascul Surg 1997;114:134 –138. Rosenquist GC, Bharati S, McAllister HA, Lev M. Truncus arteriosus communis: truncal valve anomalies associated with small conal or truncal septal defects. Am J Cardiol 1976;37:410 –412. Moss CAF, Freedom RM. Aortic arch interruption with truncus arteriosus or aorticopulmonary septal defect. Am J Roentgenol 1980;135:1011 –1016. Becker AE, Becker MJ, Edwards JE. Malposition of pulmonary arteries (crossed pulmonary arteries) in persistent truncus arteriosus. Am J Roentgenol 1970;110:509 –514. Wolf WJ, Casta A, Nichols M. Anomalous origin and malposition of the pulmonary arteries (crisscross pulmonary arteries) associated with complex heart disease. Pediatr Cardiol 1986;6:287 –291. Mello DM, McElhinney DB, Party AJ, Silverman NH, Hanley FL. Truncus arteriosus with patent ductus arteriosus and normal aortic arch. Ann Thorac Surg 1997;64:1808 –1810. Anderson KR, McGoon DC, Lie JT. Surgical significance of the coronary arterial anatomy in truncus arteriosus communis. Am J Cardiol 1978;41:76 –81. Suzuki A, Ho SY, Anderson RH, Deanfield JE. Coronary arterial and sinusal anatomy in hearts with common arterial trunk. Ann Thorac Surg 1989;48:792 –797. Yoo SJ, Lee Y-H, Kim ES, et al. Three-vessel view of the fetal upper mediastinum: an easy means of detecting abnormalities of the ventricular outflow tracts and great arteries during obstetric screening. Ultraound Obstet Gynecol 1997;9:173 – 182. Yoo S-J, Lee Y-H, Cho KS. Abnormal three-vessel view at sonography: a clue to the diagnosis of congenital heart disease in the fetus. Am J Roentgenol 1999;172:825 –830. Driscoll DA, Goldmuntz E, Emanuel BS. Detection of 22q11 deletions in patients with conotruncal cardiac malformations, DeGeorge, velocardiofacial, and conotruncal anomaly face syndromes. In: Clark EB, Markwald RR, Takao A, editors. Developmental mechanisms of heart disease. New York: Futura Publishing Co; 1992. p. 569 –575.
Cardiac imaging in common arterial trunk Shi-Joon Yooa,*, Yang Min Kima, Eun Jung Baeb, Seong Ho Kimb, Jung Yeon Choic, In Sook Parkd, Heung Jae Leee a
Department of Radiology, Sejong Heart Institute, Puchon, South Korea Department of Pediatrics, Sejong Heart Institute, Puchon, South Korea c Department of Pediatrics, Seoul National University Children’s Hospital, Seoul, South Korea d Department of Pediatrics, Asan Medical Center, University of Ulsan, Seoul, South Korea e Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University, Seoul, South Korea b
Abstract The diagnosis of common arterial trunk (truncus arteriosus communis) is suspected when the chest radiogram shows a combination of cardiomegaly with oval configuration, increased pulmonary vascularity, narrow superior mediastinum, concave pulmonary arterial segment and right aortic arch in a patient with cyanosis and cardiac murmur. In most cases, echocardiography can provide complete morphological information of common arterial trunk and its associated lesions, although magnetic resonance imaging can provide more objective images with clearer visualization of the adjacent mediastinal structures including thymus. Cardiac catheterization for calculation of pulmonary vascular resistance should be performed for patients older than 3 months. When catheterization is performed, angiograms are obtained for a better understanding of the pathology. The ventricular septal defect and overriding common arterial trunk are best shown in long axis view. The dominant vessel arising from the common arterial trunk is the aorta in the majority of cases. When the ascending aorta is smaller than the pulmonary artery, associated interruption of the aortic arch should be suspected. The origin of the pulmonary artery from the common arterial trunk can be seen in right and left anterior oblique views. Preferred echocardiographic views for evaluation of the pulmonary arterial anatomy are high-parasternal and suprasternal views. Truncus arteriosus can be diagnosed in the fetus by using high-resolution sonography. For fetal screening of common arterial trunk, a three-vessel view is very helpful. It is an orthogonal transverse view of the fetal upper mediastinum where the main pulmonary artery, ascending aorta and superior vena cava are arranged in a line. When there are only two vessels in the three-vessel view, common arterial trunk is suspected. Once the diagnosis of common arterial trunk is made in the fetus, fluorescent in situ hybridization (FISH) should be performed to exclude del 22(q11) or CATCH 22 syndrome. 䊚 2002 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Common arterial trunk; Truncus arteriosus; Chest radiography; Echocardiography; Angiography; Magnetic resonance imaging
1. Introduction Common arterial trunk, which is also called truncus arteriosus, persistent truncus arteriosus or truncus arteriosus communis, refers to a condition in which a single arterial trunk arises from the heart through a single arterial valve and gives rise to the aorta, one or both pulmonary arteries, and coronary arteries w1–5x. When a single arterial trunk arises from the heart, but the pulmonary arteries to both lungs arise from the descend*Corresponding author. Department of Diagnostic Imaging, Hospital for Sick Children, University of Toronto, 555 University Avenue, Toronto, Ontario, M5G 1X8, Canada. Tel.: q1-416-813-6037; fax: q1-416-813-7591. E-mail address: [email protected] (S.-J. Yoo).
ing aorta or the branches of the aortic arch (Collett and Edwards Type IV truncus w2x), it is usually considered as a variant of tetralogy of Fallot with pulmonary atresia w3–5x. By using this definition, the hemitruncus in which one pulmonary artery arises from the ascending aorta and the other from the main pulmonary artery, is a misnomer because two discrete arterial trunks arise from the heart through two separate arterial valves. Various clinical and pathological features are described in the other papers in this issue. In this paper, we will discuss how the patients with common arterial trunk present themselves in their initial chest radiograms, and how their pathological features of clinical and surgical importance should be analyzed using echocardiography, magnetic resonance imaging and angiography.
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2. Chest radiography
Fig. 1. Frontal chest radiogram from a cyanotic newborn shows marked cardiomegaly with a biventricular enlargement pattern and increased pulmonary vascularity.
As in other cardiac problems, the initial approach to the diagnosis of common arterial trunk includes taking chest radiograms as well as assessment of the patient’s symptoms and signs. The diagnosis of common arterial trunk is suspected when the chest radiogram shows cardiomegaly and increased vascularity in a patient with cyanosis and cardiac murmur (Figs. 1–3) w6x. The combination of cyanosis, cardiomegaly and increased pulmonary vascularity is also seen in patients with total anomalous pulmonary venous connection, tetralogy of Fallot with pulmonary atresia and large aortopulmonary collateral arteries, complete or corrected transposition of the great arteries or its variants without pulmonary stenosis, and various forms of univentricular atrioventricular connections without pulmonary stenosis. In common arterial trunk, cardiomegaly is usually due to biventricular and left atrial enlargement w6–9x. The cardiac configuration is commonly oval as in complete transposition of the great arteries and pulmonary atresia with intact ventricular septum (Figs. 2 and 3). The oval cardiac configuration in these conditions is produced by combination of biventricular enlargement, and absence
Fig. 2. (a) Frontal chest radiogram from a cyanotic newborn with hypocalcemia shows moderate cardiomegaly with oval configuration and increased pulmonary vascularity. The pulmonary conus is not prominent, but the right hilum is rather high. The superior mediastinum is narrow due to thymic hypoplasia. (b) and (c). Coronal and axial T1-weighted magnetic resonance images show a hypoplastic thymus (T). The main pulmonary artery (P) arises from the left wall of the common arterial trunk (Tr). Asascending aorta.
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Fig. 3. (a) Frontal chest radiogram shows moderate cardiomegaly and increased pulmonary vascularity. Note some bulging of left upper mediastinum (arrows) and straight left upper heart border (arrowheads). (b) Coronal T1-weighted magnetic resonance image shows that the thymus (T) forms the left upper mediastinal border masking the narrow vascular pedicle.
or hypoplasia of the right ventricular outflow tract that forms a bulk in the left upper corner of the ventricular mass below the left atrial appendage in normal individuals. In the common arterial trunk, the left upper heart border tends to be straight (Fig. 3) w7–9x. The heart may also show a right ventricular enlargement pattern in some cases. The superior mediastinum tends to be narrow, especially when the right and left pulmonary arteries arise directly from the posterior wall of the common arterial trunk without intervening main pul-
monary artery. Narrow superior mediastinum may be also due to regression of thymus due to a stressful patient’s condition, or due to actual hypoplasia or aplasia in association with DiGeorge syndrome (Fig. 2). The pulmonary arterial segment of the left heart border is usually concave as in tetralogy of Fallot with or without pulmonary atresia. When the main pulmonary artery arises from the left wall of the common arterial trunk (Collett and Edwards Type I truncus), however, the pulmonary arterial segment may be convex (Fig. 4).
Fig. 4. (a) Scout cineradiogram for truncal angiography in (b) shows that the superior mediastinum is wide and the pulmonary conus segment is full. (b) Truncal angiogram in frontal projection shows that the left pulmonary artery (LPA) arising from the main pulmonary arterial segment is responsible for fullness of the left upper mediastinum. Asascending aorta.
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Fig. 5. Frontal chest radiogram shows moderate cardiomegaly. There is a right aortic arch forming a vertical paravertebral shadow (arrows) on the right side.
Either or both of the left or right pulmonary arteries may arise at a higher level than normal and can be seen as a discrete structure (Fig. 2). The aortic arch is commonly high-arched and rather prominent. Right aortic arch is present in 25–50% (Fig. 5) w3–11x. The pulmonary vascularity is markedly increased in most cases (Figs. 1–3). The hypervascular lungs are commonly associated with segmental atelectasis, hyper-
Fig. 7. Left ventriculogram in long axial oblique view shows a large ventricular septal defect (D). A single arterial trunk (Tr) arises from both ventricles and bifurcates into the aorta (A) and the pulmonary artery (P). LVsleft ventricle, RVsright ventricle.
aeration and pneumonia (Fig. 6). Paradoxically, when the pulmonary vascularity is normal or only slightly increased and the lungs are clear, development of significant pulmonary vascular obstructive disease should be suspected, especially when the patient is old. Rarely, the pulmonary vascularity is decreased because of underdevelopment of the pulmonary trunk and branch pulmonary arteries. The pulmonary vascularity of the right and left lungs as well as the lung volume may not be equal when a pulmonary artery is hypoplastic or absent w9 x . To summarize the chest radiographic findings, a combination of cardiomegaly with oval configuration, increased pulmonary vascularity, narrow upper mediastinum, concave pulmonary arterial segment and right aortic arch in a cyanotic patient strongly suggests the diagnosis of common arterial trunk. 3. Echocardiography, magnetic resonance imaging and angiography
Fig. 6. Frontal chest radiogram shows marked cardiomegaly and increased pulmonary vascularity. Pneumonia with air-bronchograms is evident in the right upper lung. Multiple areas of segmental atelectasis are seen in both lungs.
Echocardiography can provide complete morphological information of common arterial trunk and its associated lesions in most cases, although magnetic resonance imaging can provide objective images with clearer visualization of the adjacent mediastinal structures w7,12–15x. Magnetic resonance imaging is useful when the overinflated lungs interfere with the echocardiographic evaluation w7,15x. When DiGeorge syndrome
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Fig. 8. (a) T1-weighted magnetic resonance image in long axis view shows a large ventricular septal defect (D). A single arterial trunk (Tr) arises from both ventricles and bifurcates into the aorta (A) and the pulmonary artery (P). (b) Subcostal long axis echocardiogram shows a lumpy and dysplastic truncal valve (arrows). The valve was both stenotic and regurgitant. (c) Right ventriculogram in left anterior oblique view shows crossed pulmonary artery (arrows). Because of crossing of pulmonary arteries, the right pulmonary artery (R) is seen below the left pulmonary artery (L) in long-axis magnetic resonance image shown in (a). LVsleft ventricle, RVsright ventricle.
is suspected, magnetic resonance imaging may be particularly useful as it clearly defines the status of the thymus (Fig. 2). Cardiac catheterization should be performed for calculation of pulmonary vascular resistance in patients older than 3 months. When catheterization is performed, angiograms are also obtained as they provide a better overview of the pathology and can sometimes demonstrate unexpected associated lesions w7,9,16–19x. However, angiography should not be performed when significant pulmonary vascular obstructive disease is suspected. Whatever the imaging modality is, the basic pathological features of the common arterial trunk can be best shown in the long axis images. The ventricular septal defect is typically large and occupies the region immediately below the overriding common arterial valve in
the majority of cases (Figs. 7 and 8a and Fig. 9). The findings seen in the long axis images are similar to those seen in patients of tetralogy of Fallot with or without pulmonary atresia. More frequently, the lower border of the ventricular septal defect is not in direct contact with the membranous septum, the truncal valve being separated from the tricuspid valve by an intervening muscular rim w4,9,16,18x. This muscular rim is formed by fusion of the ventriculo-infundibular fold and the posterior limb of the trabecula septomarginalis. It can be well outlined by right ventriculography in right anterior oblique view or sectional imaging in an equivalent view (Fig. 10). Less frequently, the lower border of the defect is in direct contact with the membranous septum, and thus the defect is a perimembranous type. In this occasion,
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Fig. 9. Parasternal long axis echocardiogram shows a ventricular septal defect (D) below the common arterial trunk (Tr). LVsleft ventricle, RVsright ventricle.
the truncal valve is in direct continuity with the tricuspid valve (Fig. 11). Rarely, the ventricular septal defect is restrictive or not present w3,5,20–23x. In most cases, the truncal valve is in fibrous continuity with the mitral valve w9x. The common arterial trunk usually arises from both ventricles through an overriding truncal valve (Figs. 7 and 8a). It often arises predominantly or exclusively
Fig. 11. So-called en-face magnetic resonance image shows a cutthrough section of the ventricular septum containing the defect (D). Notice that the truncal valve is in direct contact (arrow) with the tricuspid valve without intervening muscular rim. Thus, the defect is a perimembranous type. Trscommon arterial trunk.
from the right and less frequently from the left ventricle (Fig. 12) w10x. The number of truncal valve cusps can be best assessed by echocardiography in the short axis plane of the valve. The truncal valve is frequently
Fig. 10. (a) Right ventriculogram in elongated right anterior oblique view shows that the truncal valve is separated from the tricuspid valve by an intervening muscular rim (asterisks). It indicates that the ventricular septal defect is a non-perimembranous type. The right (R) and left (L) pulmonary arteries arise directly from the common arterial trunk (Tr). (b) Cine magnetic resonance image in semicoronal view shows comparable but clearer anatomy of pulmonary arterial origins. Asascending aorta, RAsright atrium, and RVsright ventricle.
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Fig. 12. (a) T1-weighted magnetic resonance image in four-chamber view shows a large perimembranous ventricular septal defect (D) in the inlet septum. (b) Magnetic resonance image in steep left anterior oblique view shows that the common arterial trunk (Tr) arises completely from the right ventricle with a long muscular conus. The truncal valve is remote from the ventricular septal defect. Asaorta, LAsleft atrium, LVs left ventricle, Pspulmonary artery, RAsright atrium, and RVsright ventricle.
thickened or dysplastic w10x. It is often regurgitant and occasionally stenotic (Fig. 8b) w9x. The morphology and function of the truncal valve can be assessed by twodimensional and Doppler echocardiography, as well as by angiography in long axis view.
The dominant vessel arising from the common arterial trunk is the aorta in the majority of cases. However, the ascending aorta is smaller than the pulmonary artery when there is interruption of the aortic arch (Fig. 13) w9,16,17,19,24x. This condition may be potentially con-
Fig. 13. (a) Trucal angiogram in left anterior oblique view shows that the common arterial trunk (Tr) bifurcates into the large main pulmonary artery (P) and the small ascending aorta (A). The pulmonary artery is continuous with the descending aorta (a) through a narrow ductus arteriosus (pda). (b) Late frame of truncal angiogram in frontal view shows that the aortic arch is interrupted between the origins of the left common carotid (LCA) and left subclavian (LSA) arteries. RIAsright innominate artery.
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Fig. 14. Suprasternal short axis echocardiogram shows the origins of the right (R) and left (L) pulmonary arteries from the posterior wall of the common arterial trunk (Tr) without intervening main pulmonary arterial segment.
Fig. 16. Truncal angiogram in lateral view shows that the origin of the left pulmonary artery (L) from the common arterial trunk (Tr) is much higher than that of the right (R).
fused with an aortopulmonary septal defect w17,24x. When there is interrupted aortic arch, the common arterial trunk tends to arise predominantly from the right ventricle w4,10x.
Fig. 15. Truncal angiogram in frontal view shows that both right (R) and left (L) pulmonary arteries arise more distally from the common arterial trunk (Tr).
Fig. 17. Aortogram in frontal view shows so-called Collett–Edwards type IV truncus. Each lung is supplied by a branch from the descending aorta. This condition is now considered a variant of tetralogy of Fallot with pulmonary atresia and major aortopulmonary collateral arteries. In most cases with pulmonary atresia, each lung is supplied by more than one collateral arteries.
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Fig. 18. Normal three-vessel view at fetal echocardiography. It is an orthogonal transverse view of the upper mediastinum. Oblique section of the main pulmonary artery (P), and cross-sections of the ascending aorta (A) and superior vena cava (V) are aligned in a straight line and sized in decreasing order. This view facilitates the diagnosis of a common arterial trunk as well as the anomalies of the ventricular outflow tracts, great arteries and superior vena cava in the fetus: as descending aorta; dsductus arteriosus; ltsleft; rtsright; Ssspine; and Tstrachea.
The origin of the pulmonary artery from the common arterial trunk can be seen in the right and left anterior oblique angiograms, or equivalent sectional images. When there is a main pulmonary arterial segment, it usually arises from the left wall of the common trunk (Fig. 2b and Fig. 4b). When there is no main pulmonary arterial segment, the right and left pulmonary arteries
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usually arise from the posterior wall of the common trunk (Figs. 10 and 14). In rare occasions, they may arise more distally from the common arterial trunk (Fig. 15), or one pulmonary artery may have more distal origin from the common arterial trunk than the other (Fig. 16) w18x. The length of the main pulmonary artery when present can be best defined by sectional imaging in the sagittal plane or angiography in left anterior oblique view with some cranial angulation w17x. Preferred echocardiographic views for the evaluation of the pulmonary arterial anatomy are high-parasternal and suprasternal views (Fig. 14) w12,14x. Magnetic resonance images can be obtained along the long axis of the pulmonary artery, facilitating clear delineation of the surgical anatomy (Fig. 10b). Rarely, the right and left pulmonary arteries cross each other especially when there is interruption of the aortic arch (Fig. 8) w10,25,26x. Crossed pulmonary artery should be suspected by echocardiography when normal bifurcation of the branch pulmonary arteries is not recognized and an anomalous pulmonary artery, which is the right pulmonary artery is seen beneath the left pulmonary artery (Fig. 8a,c) w26x. Rarely, the right or left pulmonary artery is absent or interrupted. On this occasion, pulmonary vein wedge angiography or preferentially white blood pool magnetic resonance imaging should be performed. Collett and Edwards Type IV truncus is usually considered as a variant of pulmonary atresia with ventricular septal defect, in which each lung is almost always supplied by multiple branches from the descending aorta or the branches of the aortic arch with few exceptions (Fig. 17) w3–5x. The pulmonary arteries are usually engorged and frequently tortuous. When the pulmonary vascular obstructive disease develops, the pulmonary arteries
Fig. 19. (a) Three-vessel view from a fetus with common arterial trunk shows only two vessels, the common arterial trunk (Tr) and superior vena cava (V). A similar three-vessel view may be seen in the tetralogy of Fallot with pulmonary atresia. (b) Oblique view of the common arterial trunk shows that it bifurcates into the ascending aorta (A) and the main pulmonary artery (P). asdescending aorta; Lsleft pulmonary artery; ltsleft; Rsright pulmonary artery; RAsright atrium; rtsright; RVsright ventricle; and Ssspine.
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Fig. 20. (a) Three-vessel view from another fetus shows only two vessels. The main pulmonary artery (P) arises from the left lateral wall of the common arterial trunk (Tr). The descending aorta (a) is seen on the right anterior aspect of the spine (S) as there was a right aortic arch. (b) Ventricular outflow tract view shows a large ventricular septal defect (D). The common arterial trunk arises exclusively from the left ventricle (LV), which is rare. LsIeft pulmonary artery, LTsleft, Rsright pulmonary artery, RTsright, and RVsright ventricle.
taper down abruptly, and the peripheral branches become obliterated, giving rise to an appearance of a pruned tree. With advanced disease, the background haze of capillary staining on pulmonary arterial wedge injection is reduced and inhomogeneous. The pulmonary circulation time tends to be prolonged. The aortic arch is often high-arched. As discussed, right aortic arch is common (Fig. 5) w3–11x. When there is a right aortic arch, the branching pattern is usually mirror-imaged. Anomalous origin of the right or left subclavian artery may be associated in a minority of cases w11,16x. Very rarely, the aorta is double-arched. The aortic arch is interrupted in up to 20% of cases w3,5,10,11,24x. When interrupted, it is usually after the origin of the left common carotid artery. This is in contrast to an aortopulmonary septal defect that is found usually with interruption distal to the origin of the left subclavian artery w24x. The ductus arteriosus is an essential pathway when the aortic arch or proximal left pulmonary artery is interrupted, while the ductus is usually absent when the aortic arch is patent (Fig. 13) w3,5,11,27x. There is considerable variation in the origins of the coronary arteries w4,9,10,28,29x. High take-off of one or both coronary arteries from the truncus or pulmonary artery is common. A single coronary artery is also common. Usually, the sinus located posteriorly or right laterally does not give rise to a coronary artery.
depend much on a so-called ‘three-vessel view’ for the diagnosis of congenital heart diseases affecting the ventricular outflow tracts andyor great arteries (Fig. 18) w30,31x. A three-vessel view is an orthogonal transverse view of the fetal upper mediastinum, in which the oblique section of the main pulmonary artery and the cross-sections of the ascending aorta and superior vena cava are arranged in a straight line and sized in decreasing order. It may be obtained simply by moving the sonographic transducer cranially along the fetal long axis from the well-known four-chamber plane. The diagnosis of a common arterial trunk is suspected when only two vessels are identified in the three-vessel view, although pulmonary atresia with absent or diminutive main pulmonary artery should be included in the differential diagnosis (Figs. 19 and 20). The diagnosis of a common arterial trunk may be entertained when the ventricular outflow tract view demonstrates a ventricular septal defect and single arterial trunk, which gives rise to the pulmonary artery or arteries and continues as the aortic arch. Once the diagnosis of common arterial trunk is made by fetal echocardiography, chromosomal study with fluorescent in situ hybridization (FISH) analysis should be performed to exclude deletion of 22(q11) or CATCH 22 syndrome w32x. The status of thymus can also be evaluated using ultrasound. The prenatal diagnosis of common arterial trunk enables initiation of appropriate treatment immediately after birth when the parents continue their pregnancy.
4. Fetal echocardiography References Typical anatomical features of common arterial trunk can be demonstrated by using high-resolution sonography. However, it is often difficult to reliably demonstrate the small pulmonary arteries arising from the common arterial trunk, especially in early gestational period. We
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