D-Transposition of the Great Arteries
In D-transposition of the great arteries, the aorta arises from the right ventricle and the pulmonary artery from the left ventricle. Mixing of blood between the two sides of the heart is essential for survival. Emergency treatment with a "balloon septostomy" shortly after birth may be necessary to improve mixing of blood between the two sides of the heart before more definitive surgery is performed.
Definitive treatment of D-transposition of the great arteries for patients born during the 1960s and 1970s consisted of an atrial baffle procedure-- either a Mustard or a Senning repair. Both of these operations redirect unoxygenated blood through the left ventricle into the lungs while oxygenated blood is baffled through the right ventricle into the aorta to supply the systemic circulation.
Most of the long term problems with these operations relate to the use of the right ventricle as the systemic pumping chamber and the development of arrhythmias.
In particular, significant impairment of right ventricular function can lead to congestive heart failure. A rapid heart rhythm known as atrial flutter can develop and may require medications or an ablation procedure. Progressive slowing of the heart rate over time may require treatment with a pacemaker. Baffle obstruction or leak is more commonly seen in children but may also be noted in adults. Late sudden death also occurs in a small percentage of patients.
During the 1980s, the Mustard and Senning operations were replaced by a procedure known as the Arterial switch. This operation results in full anatomic correction of D-transposition. The aorta and pulmonary artery are reconnected to the correct anatomic chambers and the coronary arteries are reimplanted into the new aortic root.
After the arterial switch operation, the right and left ventricles are correctly restored to the pulmonary and systemic circuit, respectively. The atrial arrhythmias which are commonly seen after the Mustard and Senning operations are likely avoided. It is, however, important to recognize that the follow-up period after the arterial switch has been much shorter and very few of these patients have reached adulthood.