D-Transposition of the Great Arteries

Treatment

As the openings between the heart’s left and right sides narrow, the oxygen delivered to the child’s body decreases. The first steps in treating the defect aim to stabilize the baby’s condition. These steps are designed to keep blood flowing through the openings:

• A medication called prostaglandin E1 (PGE) is given to keep the ductus arteriosus open.
• A balloon-tipped catheter (a long, thin tube) is guided through the child’s arteries to the natural hole between the left and right atria (the foramen ovale). Once appropriately positioned, the balloon is inflated to “tear” and enlarge the opening between the upper chambers of the heart. This enlargement promotes more mixing of blood between the two sides of the heart, thus increasing the amount of oxygen in the blood going out to the body.

These steps help increase the level of oxygen in the blood going out of the body, but it never reaches normal levels. After the baby’s condition is stabilized, surgical repair is performed within one to two weeks of age. In this open-heart procedure, a surgeon switches the two great vessels to their normal positions so that the aorta emerges from the left ventricle and the pulmonary artery from the right ventricle. The coronary arteries have to be switched as well so that they are connected to the aorta after surgery. In addition, the openings between the left and right sides of the heart are closed, and the patent ductus arteriosus is tied off and closed.

Follow-up care into adulthood

Later, narrowing (stenosis) at the arterial connections or within the branch pulmonary arteries may develop. Treatment, either with a balloon catheter and insertion of a metal, mesh cage (stent) or with surgery, may be needed to widen them. Patients are also usually watched for the rest of their lives to monitor for narrowing of the coronary arteries.

If you’ve had the Mustard or Senning procedure

These angiogram images are from a 25-year-old who had previously undergone a Mustard procedure.

All images also show a pacemaker generator (which houses the battery and the circuitry that creates the impulses that are sent to the heart), with pacing leads (wires that deliver electrical impulses to the heart muscle) implanted through the stented vein.

Over time, it became clear that patients who had undergone an older, formerly used corrective procedure, the Mustard or Senning procedure, developed problems later in life, despite an initial belief that the surgery had “cured” them. Rather than “switching” the vessels, the Mustard or Senning procedure had been used to redirect blood flow with a baffle, a surgically created structure that redirects the flow of blood within the heart or its major blood vessels. Even today, it’s common for patients who underwent the Mustard or Senning procedure to see a specialized cardiologist for the first time 20 years or more after the surgery.

Most of the problems related to the Mustard or Senning procedure result because the anatomic right ventricle of the heart was never meant to pump blood to the whole body. Patients undergoing the procedure often develop signs of heart failure or reduced function of the heart’s right pumping chamber. Reduced function, as well as leakiness of the valve between the heart’s upper and lower right chambers, often cause the right upper chamber (the atrium) to become enlarged.

Enlargement of the ventricle or the numerous suture lines in the atria can lead to various electrical rhythm problems, such as the heart intermittently beating much too fast or much too slowly, or a combination of both. Patients whose hearts develop electrical problems often require pacemakers (small, battery-powered devices that help keep the heart beating regularly) and sometimes electrical defibrillators (devices that monitor the heart rate and deliver a strong electrical shock to restore the heartbeat to normal). The risk of sudden cardiac death in patients who have undergone the Mustard or Senning procedure is about 100 times that of the general population.

In addition to these problems, the baffle used by the surgeons in the Mustard or Senning procedure to redirect blood flow frequently develops narrowing or leaks, resulting in further problems. Sometimes, pacemaker wires must be inserted through these reconstructed areas.

If you underwent the Mustard or the Senning procedure in the past, you need a follow-up by a cardiologist who specializes in the treatment of adults with congenital heart defects. You may require particular medicines to treat heart rhythm problems and to control signs and symptoms of heart failure, as well as a catheter procedure or pacemaker implantation. If your heart function deteriorates despite medical treatment, heart transplantation may need to be considered.

Even after a successful catheter procedure and pacemaker implantation (if needed), you’ll require lifelong follow-up with a specialized cardiologist, as problems can continue.