Dextrocardia with corrected transposition in an adult - sequential segmental analysis by transthoracic echocardiography and cardiac CT

 Corresponding author: Akhil Mehrotra. Copyright © 2025 Author(s) retain the copyright of this article. This article is published under the terms of the Creative Commons Attribution Liscense 4.0. Dextrocardia with corrected transposition in an adult - sequential segmental analysis by transthoracic echocardiography and cardiac CT Akhil Mehrotra 1, *, Mohammad Shaban 2 and Faiz Illahi Siddiqui 2 1 Chief, Pediatric and Adult Cardiology, Prakash Heart Station, Nirala Nagar, Lucknow, UP, India. 2 Prakash Heart Station, Nirala Nagar, Lucknow, UP, India. World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 Publication history: Received on 29 January 2025; revised on 07 March 2025; accepted on 10 March 2025 Article DOI: https://doi.org/10.30574/wjbphs.2025.21.3.0269 Abstract Corrected transposition alongwith dextrocardia and situs inversus is a very rare entity. The hallmark of corrected transposition is discordance at atrio-ventricular and ventriculo-arterial level and that is defined as “double discordance”. This can occur as an isolated anomaly but more commonly has associated defects; most common being ventricular septal defect followed by tricuspid valve abnormalities. Other associated defects are pulmonary stenosis, systemic and pulmonary venous anomalies, univentricular physiology, ventricular dysfunction (morphological right ventricle facing systemic circulation) and association of conduction abnormalities. Dextrocardia with situs inversus, also known as mirror-image dextrocardia, accounts for nearly 40% of all dextrocardia cases and is characterized by heart chambers located exactly opposite to their normal positions. Congenitally corrected transposition of great arteries (CCTGA) may co-occur in nearly 8% of dextrocardia with situs inversus. Echocardiography and Cardiac CT play a pivotal role in defining the anatomy of such a complex association and planning the management.We report a case of a 29-year-old male who presented to our hospital with dyspnea on effort [New York Heart Association (NYHA) Functional Classification class II]. Transthoracic echocardiographic study disclosed dextrocardia, situs inversus, CCTGA, pulmonary valvular stenosis with left sided aortic arch. Cardiac CT additionally detected atrial septal defect (ASD) and sub-pulmonary stenosis. Keywords: CCTGA; Double Discordance; Echocardiography; Cardiac CT; Sequential Segmental Analysis; Dextrocardia; Situs Inversus 1. Introduction The normal anatomic position of the heart is on the thorax's left side, with the cardiac apex typically pointing to the left. Variations on the normal position of the heart and other viscera are fairly uncommon. The term “dextrocardia” specifically describes the rare congenital condition whereby the heart and apex are instead positioned on the thorax's right side. Dextrocardia has an estimated incidence of around 1 in 12,000 pregnancies [1] and may be associated with other cardiac anomalies. No predilection for race, ethnicity, or gender have been described for dextrocardia. CCTGA is a rare anomaly, with an incidence ranging from 0.03 per 1000 live births accounting for approximately 0.05% of congenital heart malformations [2]. Associated anomalies include tricuspid valve abnormalities (e.g., Ebstein's anomaly), VSD, subvalvular and valvular pulmonary stenosis, RV hypoplasia, dextrocardia, and conduction World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 275 abnormalities, including complete heart block [3]. Tricuspid regurgitation and atrioventricular conduction abnormalities are well known to progress and are significant risk factors for survival. Around the 4th or 5th decade, symptoms of exercise intolerance and dyspnoea often develop and are mainly attributable to systemic atrioventricular incompetence and/or systemic ventricular failure [4-6]. Situs inversus, identified by inverted atria, occur less frequently in these patients, representing only 34% [7, 8]. If no associated intra-cardic abnormalities coexist with CCTGA, these patients may go undiagnosed until adulthood [3]. Generally, by the fourth decade, systemic right ventricle (RV) dysfunction is clinically apparent [9]. Baron Von Rokitansky in 1875, first described CCTGA demonstrating the most unexpected combination of different cardiac segments [10]. The hallmark of this interesting malady is “double discordance” or a combination of atrioventricular and ventriculoarterial (VA) discordances in the presence of situs solitus or situs inversus [11]. Here, the right atrium (RA) is connected to morphological left ventricle (LV), which, in turn, gets discordantly connected to pulmonary artery (PA). The left atrium (LA) is similarly connected to morphological right ventricle (RV) and latter to aorta (Ao). Although anatomically discordant, the double discordances physiologically nullify each other and the circulatory pattern is similar to normal heart. Hence, it was named as “corrected TGA” [11]. It is the prototype model to analyse the segmental approach in congenital heart disease echocardiography [12]. We had a strong suspicion of CCTGA in our index patient, due to the presence of dextrocardia in an apparently healthylooking adult with mild cyanosis, hence we embarked on the sequential segmental approach to deliver a clinching anatomical diagnosis and we followed it up by Cardiac CT to confirm this complex conundrum of cyanotic congenital heart disease (Figure 1-3). (A) (B) Normal Heart Dextrocardia with corrected transposition Figure 1 Pictorial delineation of (A) Normal heart; (B) Dextrocardia with corrected transposition World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 276 Figure 2 Subcostal view. Dextrocardia, situs inversus with CCTGA. LA, left atrium; LV, left ventricle; RA, right atrium; and RV, right ventricle Figure 3 Cardiac CT in a patient of Dextrocardia with CCTGA. Volume-rendered image from anterior view provides 3D perspective of relationships of cardiac chambers and great vessels. Aortic valve is superior and to right of pulmonic valve. LA, left atrium; LV, left ventricle; RA, right atrium; and RV, right ventricle; P, pulmonary artery 2. Sequential Segmental approach to the diagnosis of congenital heart disease The segmental approach by echocardiography is very well known and has been practised effectively for last 3-4 decades [13-22]. 2.1. Sequential segmental analysis by Cardiac CT The introduction of newer technology of Cardiac CT and Cardiac MRI for analysis of cardiac segments, has made this approach simple and distinct. The strength of this approach lies in the fact that it can be used for cross-sectional imaging [23]. Segmental sequential approach by Cardiac CT consists of three stages as follows: (a) the anatomical description of each segment (viscero-atrial situs, the bulboventricular loop and the position of great vessels); (b) the relationship between each segment at the atrioventricular and ventriculoarterial levels; and (c) related intraand intersegmental abnormalities [23] (Figure 4). World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 277 (a) (b) (c) (d) (e) (f) Figure 4 Cardiac CT imaging - Sequential segmental approach for the diagnosis of dextrocardia, situs inversus, and congenitally corrected transposition of great arteries (TGA). (a) Axial image through upper abdomen shows liver on left and spleen and stomach (st) on right, consistent with situs inversus. (b) Dextrocardia, situs inversus, and congenitally corrected transposition of great arteries (TGA). Reformatted oblique coronal image through outflow tract of posterior ventricle shows muscular infundibulum (arrows) separating inflow and outflow regions and confirming that posterior ventricle is a morphologic right ventricle. Ventricle connects to aorta (A). (c) CT scan of the patient showing discordant positioning of LA and RV. (d) Enhanced sagittal chest CT indicate the discordance between the atrioventricular and ventriculoarterial connections. The right ventricle endocardium is crude and triangular in shape. (e) Axial image at level of cardiac chambers shows that morphologic left atrium (LA) is connected to a morphologic right ventricle (RV), distinguished by prominent trabeculations along its septal surface. Morphologic right atrium (RA) is connected to a morphologic left ventricle. (f) Shows that main pulmonary artery (P) is to right of ascending aorta (A), an inverted relationship, as is expected with situs inversus. PV, Pulmonary vein; LA, left atrium; RV, right ventricle. Ao, aorta; LV, left ventricle; PA, pulmonary artery World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 278 2.2. Case report A 29 year male suspected to be having congenital heart disease was referred to us for cardiac evaluation, comprehensive transthoracic echocardiography and advice regarding management. The patient presented with complaints of shortness of breath on modest effort, occasional chest heaviness and palpitation. The patient denied any history of loss of consciousness or swelling over feet. On clinical examination, the patient was healthy looking and of normal built (Figure 5). Figure 5 Facial appearance of our index patient There was mild bluish colouration of lips, tips of fingers and toes. Alongwith this there bilateral clubbing present (Figure 6). (A) (B) Figure 6 (A) Clubbing of fingers (B) clubbing of toes World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 279 The patient’s weight was 66 kg, height was 152 cm, pulse rate was 88/min, in the right arm BP was 120/80 mmHg, and SPO2 was 90 % at room air. All the peripheral pulses were normally palpable without any radio-femoral delay. On cardiovascular examination, there was presence of grade 3/6 ejection murmur in the right parasternal region. There was no clicks or gallop sound heard. Rest of the systemic examination was unremarkable. Xray chest PA view (Figure 7) was suggestive of dextrocardia with situs inversus, indicated by the presence of gastric bubble on the right side. Figure 7 Xray chest (PA view). The heart is on the right side of chest - Dextrocardia with right sided gastric bubble. The aortic knuckle is seen on the left side. Moreover, the pulmonary blood flow is decreased. On abdominal ultrasound there was left sided liver and right sided spleen (Figure 8). (A) (B) Figure 8 Situs Inversus - Ultrasound of abdomen. (A) Spleen on the right side; (B) Liver on the left side Resting ECG showed right-axis deviation of the P wave and QRS complex in lead (I) with a negative QRS complex and inverted P and T waves, a positive QRS complex in lead aVR, and absent R-wave progression in precordial leads (Figure 9). World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 280 Figure 9 Resting ECG demonstrating right-axis deviation of the P wave and QRS complex in lead (I) with a negative QRS complex and inverted P and T waves, a positive QRS complex in lead aVR, and absent R-wave progression in precordial leads 2.3. Transthoracic Echocardiography Transthoracic echocardiography (TTE) evaluations were performed by the author, using My Lab X7 4D XStrain echocardiography machine, Esaote, Italy. The images were acquired using an adult probe equipped with harmonic variable frequency electronic single crystal array transducer while the subject was lying in supine and left lateral decubitus positions. Conventional M-mode, two-dimensional and pulse wave doppler (PWD) and continuous wave doppler (CWD) echocardiography was performed in the classical subcostal, parasternal long axis (LX), parasternal short axis (SX), 4Chamber (4CH), 5-Chamber (5CH) and suprasternal views. Contemporary sequential segmental approach for echocardiographic analysis of our index patient was accomplished and the characteristic features were outlined (Figures 10-17). It is important to note that due to presence of dextrocardia TTE was performed from both left and right side of the chest. 3. 2-Dimensional Color Echocardiographysequential segmental approach Transthoracic color echocardiography exhibited multiple features as mentioned below (Figures 10-17): • Dextrocardia (Figure 10) • Situs inversus (Figure 10) • AV discordance: The morphological LA is connected to morphological RV and morphological RA is connected to morphological LV (Figure 10). Figure 10 Subcostal view - Atrio-ventricular discordance alongside dextrocardia with situs inversus. In the subcostal view, right sided LA is connected to morphological RV and left sided RA is connected to morphological LV. la, left atrium; ra, right atrium; lv, left ventricle; rv, right ventricle; mv, mitral valve; tv, tricuspid valve; vs, ventricular septum; as, atrial septum World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 281 ⚫ VA discordance: Aorta is arising from morphological RV and PA is arising from morphological LV (Figures 11, 12). (A) (B) Figure 11 Apical 5C view. Ventriculo-arterial discordance demonstrated by morphological RV is connected to aorta and morphological LV is connected to PA in (A) and (B). lv, left ventricle; RV, right ventricle; vs, ventricular septum; AO, aorta; pa, pulmonary artery; av, aortic valve Figure 12 Ventriculoarterial discordance is revealed in parasternal LX view. PA is arising from morphological LV. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; VS, ventricular septum; MV, mitral valve; PA, pulmonary artery; RT, right; LX, long axis ⚫ L-loop ventricles: Morphological LV is lying to the right of morphological RV (Figure 13). World Journal of Biology Pharmacy and Health Sciences, 2025, 21(03), 274-290 282 Figure 13 L-loop ventricle morphological LV is lying to the right of morphological RV. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; VS, ventricular septum; tv, tricuspid valve; as, atrial septum; laa, left atrial appendage • Confluent pulmonary arteries • L-transposition of great arteries : Aorta and PA are transposed, with the aorta lying anterior and to the left of PA (Figure 14). Figure 14 Parasternal SX view - L-transposition of great arteries alongwith dextrocardia: spatial relationship of great arteries. Aorta is lying anteriorly and to the left of Pulmonary artery; PA is lying posteriorly and to the right of AO. 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