Hemitruncus with ventricular septal defect in a 6-year-old child
A 6-year-old girl had presented with history of recurrent episodes of lower respiratory tract infection since 3 months of age and easy fatigability of 4 years duration. The frequency of chest infections had decreased during the last 2 years. There was no history of cyanosis. On examination the child was fairly built and nourished. Her pulse rate was 102/min, and blood pressure was 110/64 mm Hg. The apex beat was in the 6th intercostal space lateral to mid clavicular line. On auscultation thesecond heart sound was loud and single. A soft systolic murmur of grade 2/6 was heard in left 2nd/3rd intercostal space.\nChest roentgenogram [] showed cardiomegaly with a cardiothoracic ratio of 0.70 and left ventricular type of apex with dilatation of pulmonary trunk and proximal pulmonary arteries. Transthoracic echocardiography showed an enlarged left ventricle, a large malaligned sub aortic ventricular septal defect (VSD) with bidirectional shunt. There was evidence of severe pulmonary arterial hypertension. The pulmonary artery confluence was not clear. Cardiac catheterization revealed a systemic saturation of 93% and systemic pulmonary artery pressures. The left pulmonary artery (LPA) pressure and saturation was 106/46 and 83% respectively. The aortic pressures and saturation was 120/69 and 93% respectively. The superior vena cava saturation was 65%. Calculation of flows and resistances in this situation using Fick's principle has many fallacies. The relative contribution of the right lung in real oxygenation is likely to be small as the saturation at entry is 93%. The whole right sided cardiac output, in the absence of significant right-to-left shunt traverses the left lung. Based on these assumptions, the calculated PVRI for left lung was 8.9 Wood Units. Calculation of right sided PVRI may be impossible with conventional principles. The angiogram showed a large sub aortic VSD with aortic override of < 50%, and the RPA arising anomalously from the ascending aorta. The LPA was seen to be a continuation of the main pulmonary artery that was arising normally from the right ventricle. In this case, aortic saturation of 93%, wide pulse pressure and low left lung PVRI supported the clinical assessment of operability. CT angiogram [] showed the RPA (1.08 × 1 cm) was arising from aorta approximately 2 cm from aortic valve leaflet without ostial narrowing, and main pulmonary artery (1.6 × 1.5 cm) was continuous with the left pulmonary artery (1.1 × 1 cm). An echocardiogram was repeated that showed continuous flow signals into the RPA without ostial narrowing. There was no pulmonary regurgitation.\nSingle stage repair was planned. Through a standard median sternotomy approach, aorta, LPA, and RPA were dissected and mobilized. On cardiopulmonary bypass (CPB), the RPA was divided from the ascending aorta and its aortic end was sutured primarily. An arteriotomy was made in the MPA at the lateral aspect just opposite to MPA-LPA junction and RPA was anastomosed to MPA with a continuous 6-0 prolypropylene suture. The VSD was then closed through the right atrium using a patch; the surgically created 4mm atrial septal defect was left open. The saturation at the time of weaning from CPB was 88% on FiO2 of 100%. The measured pulmonary artery pressure was equal to the systemic arterial pressure. Transesophageal echocardiography revealed right-to-left shunting through the atrial septal defect. In the intensive care unit, elective nitric oxide was started in the usual doses in view of severe pulmonary arterial hypertension. Over the next 5 days the systemic oxygen saturations improved, the catecholamine support and nitric oxide were gradually withdrawn and she was removed from mechanical ventilator support on the 5th post-operative day. Oral medications consisted of a diuretics and sildenafil 10 mg thrice a day and she was discharged on day 9. Post operative chest X-ray [] showed normal lung vascularity on both the sides and a lung perfusion scan [] three weeks following surgery showed normal perfusion of both the lungs. At follow-up transthoracic echocardiogram, the estimated right ventricular systolic pressure was 60 mm Hg.