Explain Arterial Switch Operation Surgery?
This is the operation of choice for simple transposition of the great arteries as it ensures anatomical correction. The approach is through midline incision and median sternotomy. It is usually done with a high ascending aortic cannula and direct cannulation of SVC and IVC. Patient is cooled down to 18 to 25°C and pel-fusion flow reduced. There is no need for resorting to circulatory arrest.
Alternately, the operation could be done with single light atrial cannula and resorting to brief period of circulatory arrest. Heart is arrested by cold cardioplegic solution administered ante-grade through the aortic root. It could also be supplemented by retrograde cardioplegia through the coronary sinus.
The ductus is suture ligated and divided. Mobilisation of ascending aorta, inain and branch pulmonary arteries are done before cardio-pulmonary bypass. Large piece of pericardium is harvested and preserved for reconstruction of the pulmonary artery. The aorta is transacted above the coronary ostia. Pulmonary artery is transacted proximal to bifurcation. Coronary buttons are raised from their respective sinuses. They are re-implanted into the neo aorta, which was the previous pulmonary artery. A Le Compte manoeuvre is done by taking the pulmonary artery bifurcation anterior to the aorta. Two ends of the aorta are anastornosed - proximal pulmonary artery (neo aorta) to distal aortic segment.
PFO or ASD present is closed. At this stage the baby is rewarmed and aortic clamp released and heart allowed to beat. Right atrium is closed. Pulmonary artery is reconstiucted using two pericardial patches to fill up the sinuses from where coronary buttons were raised. Left atrial pressure monitoring line is inserted either through the appendage or through right superior Pulmonary vein.
Atrial and ventricular pacing wires are inserted.
Tran oesophageal echocardiogram will help in deciding adequacy of coronary circulation by assessing global and regional wall motion. The success of arterial switch operation depends on coronary arterial button transfer; which in turn varies according to the type of origin of coronary arteries in transposition of the great arteries.