We present a rare case of two chambered heart (common atrium with common ventricle) in situs ambiguous in a 2-month-old
male child. In view of dyspnea, fatigue, and central cyanosis, the patient was referred to us with a provisional diagnosis of
congenital cyanotic heart disease. The baby had a body weight of 3.0 kg and an oxygen saturation of 80% at room air. The
auscultatory findings included a single first and second heart sound and soft Grade II/VI ejection systolic murmur. Plain
radiograph of the chest in posterior-anterior view revealed the cardiac silhouette on the midline of the thorax with base
to apex axis to left suggestive of mesocardia. Trachea bifurcating into morphologically similar bronchi (bronchi are long
and more vertical? Right sided), liver is transverse with absent fundic bubble shadow on the left side. Chest radiograph
goes in favor of right isomerism. Echocardiogram revealed inferior vena cava (IVC) on left and aorta on right, a common
atrium, single ventricle of left ventricular morphology, common atrioventricular valve with moderate regurgitation, IVC
opening into right side of common atrium, aorta on left and anterior, pulmonary atresia, left-sided aortic arch with large
patent ductus arteriosus. Again, these anomalies are commonly associated with right isomerism. Ultrasonography of the
abdomen showed absence of spleen with midline liver and IVC and aorta on the same side of spine favourig right isomerism.
The patient was posted for a palliative BlalockTaussig shunt surgery but died suddenly.
Key words: Cyanotic heart disease, heterotaxy, mesocardia, right isomerism, situs ambiguous