This is the left, right?

This is the left, right? Poster No.: C-1214 Congress: ECR 2013 Type: Educational Exhibit Authors: L.-L. Huang, L. Mitchell, S. Andronikou, F. Suleman, Z. I. Lockhat; Pretoria/ZA Keywords: Congenital, Diagnostic procedure, Ultrasound, Echocardiography, Conventional radiography, Paediatric, Abdomen, Cardiovascular system DOI: 10.1594/ecr2013/C-1214 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 24

Learning objectives To describe the morphological characteristics of heterotaxy and situs abnormalities, in particular left and right atrial isomerism. To suggest an approach in evaluating the spectrum of abnormalities associated with heterotaxy syndromes, using appropriate imaging modalities. Page 2 of 24

Background Heterotaxy is a spectrum of malformations involving abnormal right-left axis determination with an incidence of 1 in 10 000 births. Subdivision into right or left isomerism is according to the atrial appendage anatomy [1]. Thoracoabdominal visceral laterality is deranged, often accompanied by midline defects of the face and brain[2]. Studies suggest heterotaxy represents a spectrum of laterality defects with variable expression. Human genes associated with heterotaxy syndrome include ZIC3, NODAL, CFC1, ACVR2B, LEFTY2, CITED2 and GDF1 [1]. The common morphological characteristics are summarized in Table 1 [1]. Right isomerism Cardiovascular malformations Other malformations/ dysfunction Left isomerism Single atrium with bilateral right atrial appendages Mesocardia/ dextrocardia Single right ventricle Double-outlet right ventricle Atrioventricular discordance Right sided aortic arch Malposition of the great arteries Pulmonary stenosis/atresia Bilateral SVCs Bilateral rightsided lungs and bronchi: short bronchus, trilobed lungs Asplenia Symmetrical liver Bilateral left atrial appendages Unbalanced ventricles Partial anomalous pulmonary venous drainage Persistent left IVC draining into the left atrium Interrupted hepatic portion of IVC Bilateral leftsided lungs and bronchi: long bronchus, bilobed lungs Polysplenia Midline liver Page 3 of 24

Right-sided stomach Intestinal malrotation Extra-hepatic biliary atresia/ hypoplasia Extra-hepatic portal vein atresia Table 1: Common morphological characteristics of right and left isomerism in heterotaxy Patients may present incidentally when chest radiograph shows dextrocardia or a right sided stomach bubble, or with symptoms associated with cardiac defects, intestinal obstruction or immune deficiencies. Thorough radiological examination of every organ system is needed to delineate all rotational abnormalities and their associated complications in order to plan optimal management [3]. Page 4 of 24

Imaging findings OR Procedure details The presence or absence of normal situs solitus can be determined on chest radiography. Situs solitus is inferred when the aortic arch, cardiac apex and stomach bubble are positioned on the left. In situs inversus, all these structures are present on the right. In any other presentation, heterotaxy is inferred [3]. Right isomerism chest radiograph may present with dextrocardia (fig.1) or mesocardia (fig. 2) with right sided stomach bubble and right sided aortic arch whereas left isomerism may present with levocardia, left sided stomach bubble (fig. 3) and midline liver (fig. 4). Right or left Isomerism is defined by the arrangement of the pectinate muscle in relation to the vestibules of the atrioventricular junctions. There are four possible atrial appendage arrangements (fig. 5) [4]. Echocardiography defines the intracardiac and cardiovascular anatomy [3]. Right isomerism (fig. 6) is characterized by bilateral pyramidal-shaped right atrial appendages whereas left isomerism (fig. 7) is identified by bilateral finger-like left atrial appendages [4]. Right isomerism can also be associated with atrioventricular septal defect (AVSD) (fig. 8) or double-outlet right ventricle (fig. 9). Bronchopulmonary anatomy is consistent with atrial appendage structures and reinforces the diagnosis of heterotaxy. Right isomerism is associated with tri-lobed lungs with eparterial bronchi (fig. 10) whereas left isomerism is associated with bi-lobed lungs with hyparterial bronchi (fig. 11) [4]. Major lung fissures can be identified on conventional CT as hypovascular lucent bands or on high-resolution CT as sharp lines [5]. Abdominal ultrasound is performed to determine the presence of the spleen, position of liver and gallbladder, and to determine the position of the aorta and IVC. Cardiac catheterization is necessary for delineation of aorta and IVC for surgical planning. Right isomerism is characterized by abdominal aorta and IVC positioned on the ipsilateral side of the midline (fig. 12) associated with bilateral SVC (fig. 13) and left-sided IVC (fig. 14). Typical left isomerism is characterized by IVC interruption at the suprarenal level with continuation as azygous or hemi-azygous vein with the abdominal aorta and IVC located on contra-lateral sides of the midline (fig. 15) [3]. Persistent left SVC draining into right atrium (RA) (fig. 16), bilateral left pulmonary artery configuration (fig. 17) and interrupted hepatic portion of the IVC are also associated findings in left isomerism (fig. 18,19, 20). Intestinal malrotation is more common with right then left isomerism. Barium meal with follow through can show the duodenal and jejunal locations, which do not cross the midline in heterotaxy [3]. CT and MRI may be necessary if further anatomical detail is required [3]. Page 5 of 24

Images for this section: Fig. 1: Frontal chest radiograph demonstrating dextrocardia with right-sided aortic arch and right-sided stomach bubble in right isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 6 of 24

Fig. 2: Frontal chest radiograph demonstrating mesocardia with right-sided stomach bubble with prominent pulmonary vasculature in right isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 7 of 24

Fig. 3: Frontal chest radiograph demonstrating cardiomegaly with left-sided stomach bubble in left isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 8 of 24

Fig. 4: Frontal chest radiograph demonstrating left cardiac apex and midline liver in left isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 9 of 24

Fig. 5: Illustration of four possible atrial appendages. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 10 of 24

Fig. 6: 2D echocardiogram 4 chamber view demonstrating pyramidal shaped bilateral right atrial appendages. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Page 11 of 24

Fig. 7: 2D echocardiogram 4 chamber view demonstrating bilateral finger-like atrial appendages in left isomerism. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Fig. 8: 2D echocardiogram 4 chamber view demonstrating large AVSD. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Page 12 of 24

Fig. 9: 2D echocardiograph colour Doppler 4 chamber view demonstrating classic double-outlet right ventricle. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Page 13 of 24

Fig. 10: Illustration of trilobed lungs with eparterial bronchus in right isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 14 of 24

Fig. 11: Illustration of bilobed lungs with hyparterial bronchus in left isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 15 of 24

Fig. 12: Illustration showing the position of the aorta and IVC in right isomerism. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 16 of 24

Fig. 13: Cardiac catheterization AP view demonstrating bilateral SVCs in right isomerism. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Fig. 14: Cardiac catheterization AP view demonstrating persistent left sided IVC in right isomerism. Page 17 of 24

Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Fig. 15: Illustration showing interrupted IVC continuing with azygous or hemiazygous vein. The aorta is located on the opposite side of the midline. Radiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ZA Page 18 of 24

Fig. 16: Cardiac catheterization AP view showing left SVC draining into RA in left isomerism. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Page 19 of 24

Fig. 17: Cardiac catheterization caudal view demonstraing bilateral left pulmonary artery configuration. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Page 20 of 24

Fig. 18: Cardiac catheterization AP view showing interrupted IVC in left isomerism. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Fig. 19: Cardiac catheterization lateral view showing interrupted IVC in left isomerism. Page 21 of 24

Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Fig. 20: Cardiac catheterization AP view showing interrupted IVC in left isomerism. Paediatric Cardiology, University of Pretoria, Steve Biko Academic Hospital - Pretoria/ ZA Page 22 of 24

Conclusion Heterotaxy syndrome is a serious form of congenital heart disease. Despite current advances in medical and surgical management, the long term prognosis remains guarded. Right isomerism has an overall 5 year survival of 30 to 74% whereas left isomerism, due to the less complex associated cardiac defects, fares better with survival between 65 to 84% [1]. Page 23 of 24

References 1. 2. 3. 4. 5. Shiraishi, I, Ichikawa H. Human Heterotaxy Syndrome - From Molecular Genetics to Clinical Features, Management and Prognosis. Circulation Journal. Vol 76, September 2012 Allen HD, Driscoll DJ, Feltes TF, Shaddy RE. Moss and Adams' Heart Disease in Infants, Children and Adolescents. Philadelphia: Lippincott Williams & Wilkins; 2008. p.454, 645. Applegate KE, Goske MJ, Pierce G, Murphy D. Situs revisited: Imaging of the heterotaxy syndrome. Radiographics 1999: 19:837-852 Jacobs JP, Anderson RH, Weinberg PM, Walters HL, Tchervenkov CI, Del Duca D, Franklin RCG et al. The nomenclature, definition and classification of cardiac structures in the setting of heterotaxy. Cardiology in the Young. 2007; 17 (Suppl.2) 1-28 Hayashi K, Aziz A, Ashizawa K, Hayashi H, Nagaoki K, Otsuji H. Radiographic and CT appearances of the major fissures. Radiographics 2001: 21:861-874 Page 24 of 24