Congenitally corrected transposition of great arteries

Pruthvishree¹, Vetri Karunakaran²

¹Third year Emergency medicine resident, Kauvery Hospital, Alwarpet, Chennai

²Consultant, Department of Emergency medicine, Kauvery Hospital, Alwarpet, Chennai

Abstract

Congenitally corrected transposition of the great arteries (CCTGA) is rare form of congenital heart disease. It may be present with or without associated anomalies. Patients with CCTGA are usually diagnosed at early stages of life due to associated anomalies, but they may even remain asymptomatic till later decades of their life. We report a 59 year gentleman who presented to our emergency department with upper abdominal discomfort and breathing difficulty for 1 week, in whom isolated CCTGA was discovered incidentally. Further investigation revealed right ventricular hypertrophy, moderate left and right AV valve regurgitation, third-degree heart block and AV dissociation.

Background

Congenitally corrected transposition of the great arteries (CCTGA) is characterized by transposed great arteries and inversion of ventricles, atrioventricular valves, and conduction system but normal atrial situs. It is a rare abnormality, occurring in approximately 0.5 to 1.4% of all congenital heart diseases. Merely 10% of the patients with CCTGA do not have any associated anomalies like ventricular septal defect, pulmonary artery stenosis, tricuspid valve abnormalities, and mitral valve abnormalities.

The patients without any associated anomalies, that is, isolated CCTGA, remain asymptomatic for many years and are usually diagnosed in later decades of life due to abnormal ECG, cardiomegaly on chest X-ray, or murmur. Echocardiography, cardiac computed tomography, and cardiac magnetic resonance imaging, and electrocardiography are very useful towards meticulous diagnosis.

However, these patients may not be free of complications. They often present with life threatening complications like systemic ventricular dysfunction, tricuspid regurgitation, heart block, and ventricular arrhythmia. These lead to increased morbidity and mortality in such patients. By and large, the patients without associated anomalies have a normal life expectancy, but their lifespan markedly depends on the systemic ventricular function

Case presentation

A 42-year aged man, with history of diabetes, presented to emergency department with complaint of upper abdomen discomfort, belching and breathing difficulty for 2 weeks.

On examination

Airway – patent and self-maintained
Breathing – B/L Air entry was equal; B/L Fine basal crepitations were present
SpO2: 99%RA, RR: 20/min
Circulation – CVS: S1S2 was heard , Tricuspid regurgitant murmur was heard, JVP – normal
BP: 160/90, HR: 64/min
PA: soft, non-tender, no organomegaly, bowel sounds were present
Disability – GCS- E4V5M6, Moving all 4 limbs
Exposure – Temp: 98.2 F, no other external injuries.

Initial evaluation in ER

ECG: Heart rate – 66/min, 3^rd degree Heart block
Trop I: 0.01 (Negative)
Chem – 8: Na- 133; K- 4.2, Cl- 98; BUN- 6; Creatinine – 0.6; Glucose – 360; Hb – 13.9; Hct – 41%.
Echo: CCTGA, AV-VA discordance, Aorta arises from Right ventricle, Pulmonary artery arises from Left ventricle, Moderate right and left AV valve regurgitation, No Pulmonary stenosis, Adequate biventricular function.

Normal echo findings: LA (left atrium), RA (right atrium), IAS (interatrial septum), MV (mitral valve), TV (tricuspid valve), MVAL (mitral valve anterior leaflet), MVPL (mitral valve, posterior leaflet), LV (left ventricle), IVS (interventricular septum), TVAL (tricuspid valve anterior leaflet) TVSL (tricuspid valve septal leaflet) RSPV (right superior pulmonic vein) LIPV (left inferior pulmonic vein).

CCTGA Echo findings: Echocardiogram revealed that the position of the two ventricles was reversed so that the right atrium (RA) connected to the left ventricle (LV). In normal heart, we display an LV in the opposite side to echo marker. In this image, the LV is in the same side as that of echo marker. So, transposition (being corrected) of both ventricles is seen. The left atrium (LA) connects to the right ventricle (RV); also, the aorta arises from the right ventricle and supplies the systemic circulation; the pulmonary artery arises from the left ventricle and supplies the pulmonary circulation. Arrowhead is the pacing electrode in the left ventricle (AoV, aortic valve; PV, pulmonic valve)

Discussion

Congenitally corrected transposition of great vessels (CCTGA) is a rare congenital heart defect and constitutes less than 1% of all congenital heart disease. The two fundamental anatomic abnormalities in CCTGA consist of transposition of the ascending aorta and pulmonary trunk, as well as inversion of ventricles. This arrangement results in desaturated systemic venous blood passing from the right atrium through the mitral valve to the left ventricle and into the pulmonary trunk, whereas oxygenated pulmonary venous blood flows from the left atrium through the tricuspid valve to the right ventricle and into the aorta. Thus the circulation corrected functionally. The clinical presentation, course and prognosis of patients with CCTGA vary depending on the nature & severity of any complicating intracardiac anomalies, as well as development of dysfunction of the systemic subaortic right ventricle. Cardiac deaths have been attributed to the development of complete atrioventricular block, systemic ventricular dysfunction or systemic AV valve incompetence.1-4 Very rarely in patients of CCTGA, ventricular tachycardia has been attributed to the cause of sudden cardiac death. Furthermore, fatal arrhythmia is very rare in the absence of systemic ventricular dysfunction.

In about 20–50% of CCTGA patients, Tricuspid regurgitation occurs in varying degrees ensuing substantial morbidity and mortality. It has also been implicated as a cause of ventricular dysfunction. Usually with increasing age, these patients present with atrial fibrillation and flutter, but in our case the patient presented with non specific complaints. Every year around 2% of patients with CCTGA acquire complete AV block. Displacement of AV node and abnormal course of conduction tissue put the patient at risk of developing AV block.

Patients with relatively complicated CCTGA eventually require cardiac transplantation; while some patients can be managed with pacemaker implantation. More often than not, pacemaker implantations in such settings have been technically challenging because of the complex heart anatomy. Moreover, pacemaker implantation in such patients might lead to worsening of systemic ventricular function and atrioventricular valve regurgitation. The reason behind this is probably the modification in position of ventricular septum that induces a septal shift and failure of tricuspid valve cooptation. Since our patient did not require any pacing or surgical intervention at this point, he was admitted in cardiac unit for observation and was managed symptomatically and discharged home with no complications.

Conclusion

Due to the different clinical presentations and confusion with the appearance of “non-compaction” of the right systemic ventricle, the diagnosis of ccTGA remains challenging. From the ER point of view careful interpretation of the ECG and bedside echocardiogram help is diagnosis and in initiating the required investigations that guide management.

Reference

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Kaya, I. H. Tanboga, M. Kurt et al., “Corrected transposition of the great arteries with previously unreported cardiac anomalies,” Cardiovascular Journal of Africa, vol. 23, no. 5, pp. e5–e7, 2012.
Zimmermann, J. R. Altman, and D. S. Gantt, “Acute myocardial infarction with isolated congenitally corrected transposition of the great arteries,” Proceedings (Baylor University. Medical Center), vol. 29, no. 2, pp. 168–170, 2016.
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Dr. Vetri Karunakaran
Consultant – Emergency Physician

Congenitally corrected transposition of great arteries