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Year : 2020  |  Volume : 8  |  Issue : 1  |  Page : 26-29

Comparison of morphologic profile of congenital heart defects associated with right isomerism and left isomerism in Western Indian population

1 Department of Pediatric Cardiology, U. N. Mehta Institute of Cardiology and Research Centre, Ahmedabad, Gujarat, India
2 Department of Pediatric Cardiology, Choithram Hospital and Research Centre, Indore, Madhya Pradesh, India
3 Department of Research, U. N. Mehta Institute of Cardiology and Research Centre, Ahmedabad, Gujarat, India

Date of Submission22-Aug-2019
Date of Decision11-Sep-2019
Date of Acceptance18-Jan-2020
Date of Web Publication03-Apr-2020

Correspondence Address:
Dr. Prashant Agrawal
Department of Pediatric Cardiology, Choithram Hospital and Research Centre, Indore - 452 014, Madhya Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/heartindia.heartindia_39_19

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Context: Heterotaxy syndrome is a disorder that involves abnormal lateralization of the abdominal viscera, thoracic organs, and cardiac atria. The objective was to compare the frequency of morphologic profile of congenital heart defects associated with right isomerism and left isomerism in the Western Indian population.
Materials and Methods: This cross-sectional observational study was conducted by the Department of Pediatric Cardiology, U N Mehta Institute of Cardiology and Research Centre, Ahmedabad, Gujarat, India, from January 2016 to April 2018. All children presenting to the hospital with suspected congenital heart defect were included in the study. Echocardiography-based sequential segmental analysis was used; various cardiac defects were noted for patients with right isomerism (RAI) and left isomerism (LAI).
Results: Occurrence of heterotaxy in our screening population is 0.12%. A total of 93 children had atrial heterotaxy (M: F; 1.06:1), with 65 (69.89%) having RAI and 28 (30.11%) having LAI. Most common lesions associated with RAI included complete atrioventricular septal defect (n = 43, 66.2%), and pulmonary outflow tract obstruction (n = 35, 53.84%). LAI was associated with atrial septal defect (n = 24, 85.7%) ventricular septal defect (n = 23, 82.1%).
Conclusion: Heterotaxy encompasses a wide spectrum of congenital cardiac defects. The frequency of various defects associated with RAI and LAI in Western India is compared here to those as reported in the Western world.

Keywords: Congenital heart defect, heterotaxy, segmental sequential analysis

How to cite this article:
Champaneri B, Agrawal P, Jain M, Parmar T, Patel K. Comparison of morphologic profile of congenital heart defects associated with right isomerism and left isomerism in Western Indian population. Heart India 2020;8:26-9

How to cite this URL:
Champaneri B, Agrawal P, Jain M, Parmar T, Patel K. Comparison of morphologic profile of congenital heart defects associated with right isomerism and left isomerism in Western Indian population. Heart India [serial online] 2020 [cited 2023 Mar 27];8:26-9. Available from: https://www.heartindia.net/text.asp?2020/8/1/26/281880

  Introduction Top

In the normal body, the internal organs are arranged in typical patterns on the right and left sides and are not mirror images of each other. Asymmetry of the thoracic and abdominal organs is the usual or normal situation. The syndrome of visceral heterotaxy includes patients with an unusual degree of symmetry of some of the thoracic and abdominal organs and the atrial appendages within the heart. This broad term includes patients with a wide variety of very complex cardiac lesions. Patients with heterotaxy can be stratified into the subsets of asplenia syndrome and polysplenia syndrome, or the subsets of heterotaxy with isomerism of the right atrial appendages and heterotaxy with isomerism of the left atrial appendages.[1],[2] Heterotaxy is also associated with immune deficiency syndromes due to ineffective splenic function. The long-term outcome is often poor due to overwhelming infection. The heterotaxy syndrome (HS) has an estimated incidence of 1 in 6000–1 in 20,000 live births, or about 1% of all congenital heart defects.[3],[4],[5] However, if abortions and stillbirths are included, HS is found more frequently (0.03%–1.1% of fetuses).[6],[7] Interestingly, Asians show a higher prevalence of HS compared to westerners.[8] The segmental sequential analysis used for systematic evaluation of congenital cardiac defect on the basis of echocardiographic study, provides a valuable insight into individual segmental arrangement and anomalies associated with atrial heterotaxy.[8] In this study, the aim was to determine the distribution of cardiac lesions in patients with heterotaxy presenting to the tertiary care center, Ahmedabad, by analyzing and evaluating the comparison in associated cardiac anomalies with LAI and RAI conditions.

  Materials and Methods Top

All children presenting to the department with suspicion of congenital cardiac defect were evaluated from January 2016 to April 2018, following an informed consent from the parents. Those found to have heterotaxy were finally evaluated. The demographic profile and age at presentation were recorded. Echocardiography was performed by two experienced consultant pediatric cardiologists.

Atrial heterotaxy was labeled when both the atria showed similar morphology instead of usual asymmetry. LAI and RAI were differentiated on the basis of atrial appendage morphology supported by juxtaposed position of the abdominal aorta and inferior vena cava (IVC), bilateral bronchi anatomy on the chest radiograph, or abnormal P-wave vector on electrocardiogram where evident.

Statistical analysis

All statistical analysis was performed using SPSS version 20.0 (Chicago, IL, USA). Frequencies and percentages were calculated for qualitative variables, including gender, type of isomerism, and all segmental variables. Mean value and standard deviation were calculated for quantitative data. Independent t-test was used to find any significant difference in various subgroups after confirming normal distribution. Chi-square test was used as a test of significance, taking P < 0.05 as statistically significant while comparing gender, age, and various segmental anomalies in patients with LAI and RAI.

  Results Top

A total of 72,197 children were screened from January 2016 to April 2018. The age of the patients ranged from newborns to 16 years. Heterotaxy was detected in 93 patients. The diagrammatic presentation of left and right isomerism was shown in [Figure 1]. RAI was much more common 65 (69.89%) in patients with heterotaxy as compared to LAI 28 (39.11%). Heterotaxy was more common in boys (n = 48) than girls (n = 45, M: F =1.06:1). RAI was also more common in boys 37 (56.92%) than girls 28 (43.07%), while LAI was more common in girls 17 (60.71%) compared to boys 11 (39.28%). [Table 1] shows the frequency of various congenital heart defects detected in children with heterotaxy. Interrupted suprarenal IVC was not detected in any patient with LAI (P = 0.11). Various other differences in the distribution of congenital defect between LAI and RAI are presented in [Table 2]. Cardiac computed tomography image of the left isomerism and right isomerism was showed in [Figure 2] and [Figure 3]. Right-sided obstructive lesions including pulmonary stenosis (PS) or pulmonary atresia (PA), though present in both forms of heterotaxy, were significantly more common in RAI (35/65, 53.84% vs. 8/28, 28.6%; P = 0.005). The most common congenital heart disease in RAI was complete atrioventricular canal defect (AVCD) 43 (66.2%), while LAI was associated with atrial septal defect 24 (85.7%), ventricular septal defect 23 (82.1%), and univentricular heart 10 (35.7%). Left-sided obstructive lesion and hypoplastic arch were rare in both forms of heterotaxy.
Figure 1: Diagrammatic presentation of right and left isomerism. SVC: Superior vena cava, IVC: Inferior vena cava, PA: Pulmonary artery, RA: Right atrium

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Table 1: Frequency of various cardiac defects in patients with heterotaxy on segmental sequential analysis (n=93)

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Table 2: Comparison of cardiac defects in left isomerism and RAI on segmental sequential analysis

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Figure 2: Cardiac computed tomography image of classic left isomerism. (a) Interrupted inferior vena cava with hemiazygos continuation, (b) Polysplenia, (c) Ipsilateral drainage of pulmonary veins into respective atria, and (d) Hyparterial bronchus. IVC: Inferior vena cava, RSVC: Right superior vena cava, RPV: Right-sided pulmonary veins, LPV: Left-sided pulmonary veins, AS: Atrial septum, RV: Right ventricle, LV: Left ventricle, Des Ao: Descending aorta

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Figure 3: Cardiac computed tomography of classic right isomerism. (a) Absent spleen, (b) Eparterial bronchus, (c) Supracardiac total anomalous pulmonary venous connection, (d) Dextrocardia. SVC: Superior vena cava, RA: Right atrium, RPV: Right-sided pulmonary veins, LPV: Left-sided pulmonary veins, TAPVC: Total anomalous pulmonary venous connection

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  Discussion Top

Children with right atrial isomerism condition have multiple heart defects. They may have septal defects and problems with heart valves, particularly the pulmonary valve. LAI children may have septal defects as well as problems with heart valves and the heart's electrical system. RAI (69.89%) was much more common than LAI (30.11%) in the present study. The study from Taiwan and Singapore reported a similar frequency of RAI.[9],[10] Most Western and Far Eastern studies showed a high frequency of LAI in patients with heterotaxy.[11],[12],[13],[14],[15],[16] We observe male predominance for heterotaxy and right isomerism while female predominance for the left isomerism, but exact gender distribution can be made out only by including those of aborted and stillbirth fetuses. Therefore, gender cannot be used reliably to predict cardiac or splenic state in infants with suspected isomerism. LAI is usually associated with less severe cardiac defects and can occur in isolation. LAI may not come into notice until being screened for visceral abnormalities. There was no significant regional difference in our population when compared with Western literature. Interrupted suprarenal IVC was only found in patients with RAI in contrast to the previous studies.[13],[14] SVC arrangement was not significantly associated with any typical form of heterotaxy. Supracardiac total anomalous pulmonary venous connection (TAPVC) was found in 12 (18.5%) patients in RAI while none in LAI. In most children, the TAPVC was at cardiac level with pulmonary veins draining directly into RA when associated with heterotaxy; it may be due to maligned interatrial septum. This finding was in contrast with previous literature, where extracardiac TAPVC and obstructed pulmonary veins were frequently associated with atrial heterotaxy.[2],[10],[12] Interatrial septum was defective or absent in almost all cases with RAI. Ventricular septal defect was common in both forms of atrial heterotaxy. RAI mostly presented with right-sided obstructed lesions. Complete atrioventricular septal defect (66.2% vs. 32.1%) (AVSD), double-outlet right ventricle (13.8% vs. 3.6%), transposition of great arteries (TGA) with PS, or (53.84% vs. 28.6%) PA were the most common lesions in patients with RAI. This finding was in accordance with previous studies showing a high frequency of AVSD, TGA, PS, or PA associated with RAI. Left-sided obstructive lesions, though less frequent in atrial heterotaxy, are associated with poor outcome.[2]

  Conclusion Top

Atrial heterotaxy in Asian Indians is associated with a wide range of cardiac defects and can involve all segments of the heart. Asian Indians differ from caucasians in TAPVC being intracardiac in nature when associated with heterotaxy. RAI in Asian Indians is more common with AVCD and PA/stenosis, while LAI was more often associated with univentricular heart. There is a fair degree of overlap between defects associated with right and left atrial isomerism. The other association of heterotaxy data in Asian Indians shows similarities with the spectrum of congenital heart defect reported in the Western population emphasize the involvement of genetic mutations rather than regional or environmental variation resulting in defects.


The authors are grateful to the Director, Dr. R.K. Patel, and other interventional cardiologists for their valuable support in the completion of this project.

Financial support and sponsorship

This work was supported by the U N Mehta Institute of Cardiology and Research Centre itself and received no specific grant from any funding agency, commercial, or not for profit sectors.

Conflicts of interest

There are no conflicts of interest.

  References Top

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Qureshi AU, Kazmi U, Kazmi T, Sadiq M. Congenital heart defects associated with atrial heterotaxy. J Coll Physicians Surg Pak 2012;22:549-52.  Back to cited text no. 2
Moller JH, Nakib A, Anderson RC, Edwards JE. Congenital cardiac disease associated with polysplenia. A developmental complex of bilateral “left-sidedness”. Circulation 1967;36:789-99.  Back to cited text no. 3
Mierop VM, Gessner IH, Schiebler GL. Asplenia and polysplenia syndromes. Birth Defects Orig Artic Ser 1972;8:36-44.  Back to cited text no. 4
Bartram U, Wirbelauer J, Speer CP. Heterotaxy syndrome – Asplenia and polysplenia as indicators of visceral malposition and complex congenital heart disease. Biol Neonate 2005;88:278-90.  Back to cited text no. 5
Atkinson DE, Drant S. Diagnosis of heterotaxy syndrome by fetal echocardiography. Am J Cardiol 1998;82:1147-9, A10.  Back to cited text no. 6
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Kim SJ, Kim WH, Lim HG, Lee JY. Outcome of 200 patients after an extracardiac Fontan procedure. J Thorac Cardiovasc Surg 2008;136:108-16.  Back to cited text no. 8
Yan YL, Tan KB, Yeo GS. Right atrial isomerism: Preponderance in Asian fetuses. Using the stomach-distance ratio as a possible diagnostic tool for prediction of right atrial isomerism. Ann Acad Med Singapore 2008;37:906-12.  Back to cited text no. 9
Lin JH, Chang CI, Wang JK, Wu MH, Shyu MK, Lee CN, et al. Intrauterine diagnosis of heterotaxy syndrome. Am Heart J 2002;143:1002-8.  Back to cited text no. 10
Yildirim SV, Tokel K, Varan B, Aslamaci S, Ekici E. Clinical investigations over 13 years to establish the nature of the cardiac defects in patients having abnormalities of lateralization. Cardiol Young 2007;17:275-82.  Back to cited text no. 11
Hashmi A, Abu-Sulaiman R, McCrindle BW, Smallhorn JF, Williams WG, Freedom RM. Management and outcomes of right atrial isomerism: A 26-year experience. J Am Coll Cardiol 1998;31:1120-6.  Back to cited text no. 12
Ho SY, Cook A, Anderson RH, Allan LD, Fagg N. Isomerism of the atrial appendages in the fetus. Pediatr Pathol 1991;11:589-608.  Back to cited text no. 13
Sharland G, Cook A. Heterotaxy syndromes/isomerism of the atrial appendages. In: Textbook of Fetal Cardiology. London: Greenwich Medical Media; 2000. p. 335-46.  Back to cited text no. 14
Berg C, Geipel A, Smrcek J, Krapp M, Germer U, Kohl T, et al. Prenatal diagnosis of cardiosplenic syndromes: A 10-year experience. Ultrasound Obstet Gynecol 2003;22:451-9.  Back to cited text no. 15
Berg C, Geipel A, Kamil D, Knüppel M, Breuer J, Krapp M, et al. The syndrome of left isomerism: Sonographic findings and outcome in prenatally diagnosed cases. J Ultrasound Med 2005;24:921-31.  Back to cited text no. 16


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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