Modified Blalock – Taussig shunt

Modified Blalock – Taussig shunt

The original Blalock – Taussig (BT) shunt was designed by Helen B Taussig (physician) and Alfred Blalock (surgeon) at the John Hopkins Hospital. This was based on the observation by Helen B Taussig that infants with severe pulmonary stenosis or pulmonary atresia had worsening of cyanosis after spontaneous closure of ductus arteriosus. The BT shunt was an anastomosis between subclavian artery and pulmonary artery, to enhance pulmonary blood flow in those infants with severe cyanotic congenital heart disease with low pulmonary blood flow or tetralogy of Fallot like physiology.

Different techniques have been used to modify a BT shunt when it is not technically feasible to directly anastomose subclavian artery to pulmonary artery. Synthetic vascular prosthesis made of nylon, teflon and dacron have been tried. Other options were free left subclavian artery graft and interposition of azygos vein [1]. The commonly used method currently is to place a Gore-Tex graft between the right subclavian artery and the right pulmonary artery [2].

The purpose of doing a shunt is to increase pulmonary blood flow, reduce cyanosis and improve exercise tolerance. Excessive increase in pulmonary blood flow can lead to pulmonary hypertension, which used to occur with central aortopulmonary shunts. But it seldom occurs with a modified BT shunt. Obstruction of the shunt can lead to recurrence of cyanosis. Acute obstruction can occur due to shunt thrombosis [2].

Shunt take down is usually done at the time of corrective surgery [2]. It is also technically feasible to occlude the shunt by interventional procedure using an Amplatzer device [3].

References

1. Usha Kiran, Shivani Aggarwal, Arin Choudhary, B Uma, Poonam Malhotra Kapoor. The blalock and taussig shunt revisited. Ann Card Anaesth. Jul-Sep 2017;20(3):323-330.
2. Verena Dirks, René Prêtre, Walter Knirsch, Emanuela R Valsangiacomo Buechel, Burkhardt Seifert, Martin Schweiger, Michael Hübler, Hitendu Dave. Modified Blalock Taussig shunt: a not-so-simple palliative procedure. Eur J Cardiothorac Surg. 2013 Dec;44(6):1096-102.
3. Fernando Benito Bartolomé, Fredy Prada Martínez, Cristina Sánchez Fernández-Bernal. Closure of a Blalock-Taussig Shunt With an Amplatzer Device After the Fontan Operation. Rev Esp Cardiol. 2003 Aug;56(8):826-7.