An infant with truncus arteriosus with situs inversus with single atrium: A case report

Abstract

Truncus arteriosus is a rare heart defect comprising <1% of congenital cyanotic heart disease. Rarely it may be associated with single ventricle, but association with single atrium is very rare. We report a case of truncus arteriosus (Van Praag type A2) with single atrium and single ventricle.

<Learning objective: In our case truncus arteriosus was associated with single atrium, single ventricle, and situs inversus which is rare and has not been reported in the literature.>

Introduction

Truncus arteriosus is a rare heart defect comprising <1% of congenital cyanotic heart disease. Rarely it may be associated with single ventricle, but association with single atrium is very rare. We report a case of truncus arteriosus (Van Praag type A2) with single atrium and single ventricle.

Case report

A 6-month-old boy was referred to our hospital for further evaluation of breathing difficulty and poor weight gain. On clinical examination cyanosis was present; chest was hyperkinetic with a loud second heart sound. An ejection systolic murmur grade III/VI was present in the pulmonary area with a grade II/IV early diastolic murmur in the same region.

Electrocardiography revealed sinus rhythm, tall R wave in lead V1–V4 with tall, narrow base T waves in V1–V4 (Fig. 1A).

Fig. 1.

(A) Electrocardiogram showing ectopic atrial rhythm, tall R wave in lead V1–V4 with tall, narrow base T waves in V1–V4. (B) Modified apical 4 chamber view showing single ventricle (SV) with single atrium (SA). (C) Short-axis view showing right pulmonary artery (RPA) arising from truncus arteriosus (TA). (D) Suprasternal view showing left pulmonary artery (LPA) arising from TA. Ao, aorta.

Chest X-ray revealed dextrocardia, cardiomegaly, with pulmonary plethora (Fig. 1B).

Echocardiography revealed that dextrocardia with situs inversus and a large truncus arteriosus arising from single functionally right ventricle and right and left pulmonary arteries were arising from posterior aspect of truncus separately (Van Praag type 2). Functional right ventricle was connected with an outlet chamber through a ventricular septal defect. The patient had single atrium and single atrioventricular valve with complete atrioventricular canal defect and trileaflet truncal valve with mild regurgitation (Fig. 1B–D).

Multidetector computed tomography (MDCT) revealed 24 mm × 22 mm truncus arteriosus arising from single functionally right ventricle and left and right pulmonary artery was arising closely but separately from posterior aspect of truncus, 17 mm from truncal valve. MDCT also revealed right sided aortic arch, left sided inferior vena cava, normal systemic and pulmonary venous drainage (Fig. 2B–D).

Fig. 2.

(A) Chest X-ray showing dextrocardia, cardiomegaly, and pulmonary plethora. (B) Multidetector computed tomography (MDCT) sagittal section showing origin of right pulmonary artery (RPA) from truncus (Tr). (C) MDCT transverse section RPA and left pulmonary artery (LPA) arising from posterior aspect of Tr. (D) Volume rendering reconstruction of MDCT images showing origin of RPA and LPA from posterior aspect of Tr and Tr continuing as aorta (Ao).

There were no associated extracardiac defects.

Discussion

Truncus arteriosus is a rare congenital heart disease (CHD) with an incidence of 0.03–0.056/1000 live births [1]. In truncus arteriosus a single common artery arises from the heart by means of a single semi lunar truncal valve and supplies the systemic, pulmonary, and coronary circulations. Pulmonary arteries originate from the common arterial trunk distal to the coronary arteries and proximal to the first brachiocephalic branch of the aortic arch [2].

Etiology of truncus arteriosus is mostly genetic, but other causes are maternal exposure to alcohol during first trimester, maternal gestational diabetes mellitus, and exposure to teratogens such as retinoic acid and bisdiamine [1]. The genetic cause is a micro deletion of 22q11.2, which occurs in 30–40% of cases [1].

Truncus arteriosus is frequently associated with other cardiac and great vessel anomalies which are present in 34.8% of cases [3], such as right aortic arch (25–30% of cases), interrupted aortic arch, aberrant right subclavian artery, abnormal coronary arteries, atrial septal defect, tricuspid atresia, and double aortic arch.

Two classifications have been proposed for truncus arteriosus. Collett and Edward's (1948) classified truncus arteriosus into 4 types [3]. Van Praagh (1965) classified truncus arteriosus into 2 types based on the presence (type A) or absence (type B) of a ventricular septal defect (VSD) with the latter type being rare [1]. Type A was reclassified into 4 types. In type 1, main pulmonary artery is arising from common trunk and aortopulmonary septum is partially formed. Aortopulmonary septum is completely absent in type A2 and right and left pulmonary arteries directly forming from truncus. In Type A3 one pulmonary artery is absent and that lung is supplied by collateral vessels (e.g. bronchial arteries) or a pulmonary artery from a patent ductus arteriosus or major aorto-pulmonary collateral arteries from the descending aorta. Type A4 is defined not by the pattern of origin of the pulmonary arteries but by the coexistence of hypoplasia, coarctation, atresia, or absence of the aortic arch [1].

Truncus arteriosus associated with single ventricle has also been reported in the literature [4]. But in our case truncus arteriosus was associated with single atrium, single ventricle, and situs inversus which is rare and has not been reported in the literature.

Conflict of interest statement

We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.