Many agree that the Blalock-Taussig shunt (BT shunt) was one of the most important developments in the history of pediatric cardiology and cardiothoracic surgery. It is a palliative surgery that creates a connection between the pulmonary artery and a systemic artery like the carotid, or more commonly the subclavian artery. Alternately, a connection is created directly between the aortic and pulmonary arteries.
The first Blalock-Taussig shunt was performed in 1945 and represents the combined efforts of Drs. Alfred Blalock and Helen Thomas, and surgical technician, Vivien Thomas. The BT shunt was meant to address severe cyanosis or blue baby syndrome in young patients who had no surgical repair options. Presently the surgery is used in a similar manner, though it is not used as often to treat Tetralogy of Fallot (ToF) today, as was the case with the first and many subsequent BT shunt surgeries.
The principle behind the Blalock-Taussig shunt is that when inadequate oxygenation of blood is occurring, creating a connection between the pulmonary artery and another artery with oxygenated blood will reduce cyanosis through blood mixing, and better oxygenate the body’s tissues. In 1945, there was no other way to deal with heart defects that caused cyanosis, and they usually resulted in suffering and slow death. The surgery had its limitations because it could not address the underlying defects even if it solved some of their problems. It wasn’t curative; it was palliative. Numerous years passed before a true repair to ToF existed.
The development of ToF repair didn’t render the Blalock-Taussig shunt obsolete. It is still often used as a first step to palliate cyanosis in babies so they can grow before having more complex heart surgery. The BT shunt was also found to be useful for a number of different heart defects. It became standard to use the surgery with a series of staged surgeries to palliate conditions like tricuspid atresia, Epstein’s anomaly of the tricuspid valve, hypoplastic right heart, and pulmonary atresia. Some surgeons preferred and still prefer using a BT shunt as the first stage of ToF repair, especially if it presents with pulmonary atresia.
The way the BT shunt is performed has changed over time. Initially the two arteries used were connected directly together through anastomosis. Today, this method is seldom used, and connection between the two arteries is created with a gore-tex® shunt. The shunt is tiny, and, especially in newborns, it is only sufficient in size to last for three to six months before other repairs are made.
Most often, the Blalock-Taussig shunt is performed very early in life, frequently within the first few days of life. The surgery is typically quick and successful, though all cyanotic newborns and young children are at risk for complications. After surgery, babies usually need to be on blood-thinners, typically aspirin, to prevent blood clotting in the shunt. As stated before, this surgery doesn’t cure; it buys time for babies to grow so they are strong enough to undergo more complex surgeries.