Modified Blalock-Taussig Shunt


Modified Blalock-Taussig (mBT) shunt is indicated in the case of cyanosis and of heart defects that cannot be corrected by an operation on the newborn (e.g. functional univentricular heart) and when later complex biventricular correction (e.g. Senning, Rastelli or Nikaidoh operation) is planned that would carry elevated morbidity if performed in the newborn child or in early infancy. It is also indicated in the case of ductus-dependent pulmonary circulation and high-grade pulmonary stenosis/atresia with functionally single ventricle. In the case of pulmonary atresia and ventricular septal defect with adequate pulmonary vessel bed we prefer primary correction (even in newborns). In the absence of cyanosis: to promote growth of the hypoplastic native pulmonary vessel bed (e.g. with large aortopulmonary collaterals, MAPCA) or following unifocalizati


  • by transthoracic echocardiography: clarification of possible biventricular correction (e.g. Fallot, PA VSD), anatomy of the heart defect, coronary anomalies, diameter of the right and left pulmonary artery, LPA coarctation at the opening of the persistent ductus, major aortopulmonary collaterals (MAPCA), interatrial septum.
  • by heart catheterization: pulmonary artery anatomy (in particular central pulmonary arteries), origin and course of MAPCAs.


The heart-lung machine is used and the operation is performed with the heart beating. The ascending aorta or the brachiocephalic trunk (innominate artery)is clamped and a GORE-TEX® tube (3.5 mm in diameter) is anastomosed. Next, either the pulmonary main stem or the right pulmonary artery is clamped so that the distal anastomosis can be created.

Recommendations for Further Treatment

Following the BT shunt operation the patient is dependent on the shunt. If there are signs of insufficiency of the shunt, such as a sustained fall in the oxygen saturation to below 70% at rest or failure to thrive (weight increase <50g/week suggesting volume strain due to pulmonary overcirculation), the patient should be presented again in our department. The parents are given a pulse oximeter for home monitoring of the oxygen saturation, which should  be measured twice a day.

The treatment with Aspirin 2 mg/kg/day to prevent shunt occlusion and Carvedilol 0.5 -1.2 mg/kg/day in the presence of heart failure symptoms should be dose-adjusted to the increasing weight of the child.

In the further course a heart catheter examination is planned for age 3-4 months to evaluate whether the preconditions for a bidirectional cavopulmonary anastomosis are given (sufficient development of the pulmonary vessel bed, good function of the singular ventricle). For the age of 4-6 months the bidirectional cavopulmonary anastomosis is then planned. If the chhild reaches a body weight of 5 kg before this time the heart catheter examination should be performed earlier to prevent the child “outgrowing” the shunt and developing cyanosis.

We also recommend fortnightly blood tests to measure the hemoglobin (Hb) value. If the Hb falls below 14 g/dl we recommend a blood transfusion, with values of 14-16 g/dl administration of erythropoetin (1000 IU/kg/week in three doses (for example Monday, Wednesday and Friday) and with  Hb over 16g/dl continuing fortnightly checks.

Antibiotics should be given prophylactically for the known indications. Seasonal treatment with Palivizumab (Synagis®), monthly intramuscular dose of 15 mg/kg) is also necessary.
Definitive palliation (total cavopulmonary anastomosis with an extracardiac conduit) is performed when the patient is 2-3 years old (weight 12-15 kg).