Findings: The radiograph demonstrates enlarged central pulmonary arteries compatible with pulmonary arterial hypertension. The central pulmonary arteries also have calcified walls. In addition, there is deformity of the left upper ribs compatible with a prior thoracotomy. The MR confirms the presence of enlarged central pulmonary arteries and decreased signal in the central branches suggesting slow flow from elevated resistance. There is also an anastomosis between the left pulmonary artery and the descending aorta.
A. Repair of D-transposition of the great arteries usually takes place through a median sternotomy not a posterior thoracotomy as this case. Transposition repair can be done by an atrial switch operation (Mustard, Senning) in which the systemic venous and pulmonary venous blood are re-routed appropriately, and more recently by the arterial switch or Jatene operation in which the great arteries themselves are relocated to their respective ventricles. The surgical connection between the descending aorta and pulmonary artery in the test case cannot be explained on the basis of any of these operations, therefore excluding transposition as an option.
B. Repair of a patent ductus arteriosus requires ligation of the ductus. This is done through a left thoracotomy. An anastomosis between the pulmonary artery and aorta is not required. Moreover, pulmonary hypertension is not expected after surgical repair. Thus, although the rib changes can be seen after PDA repair, the pulmonary artery to aorta conduit is not consistent with this type of repair.
C. Correct. Surgical palliation of TOF usually requires anastomosis between the obstructed right heart and systemic circulation before definitive repair is performed. The Potts-Smith operation was performed in this patient. In this palliative operation, the descending aorta and left pulmonary artery are anastomosed in a side- by-side fashion through a thoracotomy. Unfortunately, a common complication of this procedure is the development of pulmonary arterial hypertension because of increased blood flow to the lungs if the size of the anastomosis is not carefully constructed. The findings of pulmonary hypertension, a left thoracotomy and the surgical anastomosis between the systemic and pulmonary circulations support the diagnosis of tetralogy of Fallot. More recently, definitive repair of tetralogy of Fallot is performed early in life when feasible, thus obviating temporizing palliating procedures. The Potts-Smith operation has essentially been abandoned.
D. An aorto-pulmonary window is a congenital defect in which there is a broad-based connection between the proximal aorta and the pulmonary artery. This condition can result in pulmonary artery hypertension if surgical repair is not done. However, the increased pulmonary flow characteristic of this anomaly prior to surgery usually regresses completely or nearly so after surgery. Repair requires closing the abnormal communication generally through an sternal splitting anterior approach. In the test patient, the left posterior thoracotomy as well as the anastomosis between the descending aorta and pulmonary artery argue against the diagnosis of aorto-pulmonary window.
E. Prior to surgical repair, the shunt in truncus arteriosus is at the level of the ascending aorta and pulmonary artery. Repair requires separation of the pulmonary arteries from the aortic segment and then reconnection to the right ventricle, usually with an aortic homograft conduit. The conduit may eventually calcify. Normal vascularity is expected after surgery. In the test patient, the pulmonary hypertension and the shunt at the level of the descending, rather than the ascending, aorta make truncus arteriosus untenable. In addition, surgical repair of truncus is performed through a sternal splitting anterior approach, not through a thoracotomy.