About Systemic to pulmonary shunts

Dear Sir we have read with interest the article by Chittithavorn et al. [1], the issue concerning shunt thrombosis in low-weight new-borns is “a déjà vu”. This complication and the mortality linked to this event, was faced at the very early experience related to the Blalock-Taussig shunt. Because of this occurrence, a tubular prosthesis instead of native subclavian artery was employed. The rationale of this modified operation has been fading away over the years. In order to avoid shunt thrombosis, the main issue is not only the size of the tubular prosthesis employed (3, 3.5 and 4 mm of diameter) but mostly where the proximal anastomosis is made: that is either subclavian or innominate artery [2]. The main idea was to use a tubular prosthesis whose diameter is greater than the subclavian artery one [3]. In such a way, the blood flow limiting factor is due to the size of the subclavian artery and not the “big” prosthesis. This detail also avoids flooding of the lungs. In the Chittithavorn et al. report the correlation of the inflow site and the size of tubular prosthesis employed is lacking [1]. Is also missing the piece of information about the inflow of shunts made by sternotomy approach. In our surgical experience, as well as in RA Jonas’s personal communication, getting the proper site for the anastomosis on the subclavian artery could be cumbersome and tricky by means of a sternotomy approach [4]. In conclusion forsaking the past will force us to walk a perilous path. References. 1. Chittithavorn V, Duangpakdee P, Rergkliang C, Pruekprasert N. Risk factors for in-hospital shunt thrombosis and mortality in patients weighing less than 3kg with functionally univentricular heart undergoing a modified Blalock-Taussig shunt. Interact CardioVasc Thorac Surg 2017;25:407-13. 2. McKayR, deLeval MR, Rees P, Taylor JF, Macartney FJ, Stark J. Postoperative angiographic assessment of modified Blalock-Taussig shunts using expanded polytetrafluoroethylene (Gore-Tex). Ann Thorac Surg 1980;30:137-45. 3. de Leval MR. Systemic-to pulmonary shunts, in Surgery for Congenital Heart Defects, 3rd Ed., edited by Stark JF, de Leval MR, Tsang VT. J. Wiley & Sons Ed., Hoboken, NJ 2006. 4. Jonas RA. Coarctation: do we need to resect ductal tissue? Ann Thorac Surg 1991;52:604-7.