The patient was diagnosed with an atrial septal defect measuring 2.7 cm. 

Embryological development of the heart begins during week five of gestational development of the fetus. There are various types of ASD determined by the defect during embryo development.  The physiologic picture of ASD will determine the clinical progression of the patient. The high-pressure system of the left side of the heart causes blood to flow through the ASD into the right atrium during atrial systole (left to right shunt, non-cyanotic). Gradually, the excess blood volume will cause tension on the pulmonary artery resulting in pulmonary vascular injury and hypertrophy to compensate. As pressure within the right heart continues to increase, blood within the heart will begin to shunt from right to left (cyanotic). The oxygen saturation of our patient at the time of presentation was 94%, confirming that he remains non-cyanotic. Eisenmenger syndrome is a complication of ASD and is established when the patient develops cyanosis and pulmonary arterial disease as a result of communication between the systemic and pulmonary systems.

Right ventricular hypertrophy is defined on echo by wall thickness greater than 5 mm. If the mean pulmonary artery pressure exceeds 25 mm Hg at rest, the patient is considered to have pulmonary hypertension. In our patient, echo reveals severe pulmonary hypertension is noted with right ventricular systolic pressure is calculated at 120 mmHg. When an ASD is diagnosed, about 10% of patients will have existing pulmonary hypertension.