Objectives: To determine if the Blalock-Taussig-Thomas shunt (BTTS) causes sufficient growth of hypoplastic branch pulmonary arteries (BPAs) to facilitate total correction or definitive palliation of cardiac lesions. Methods: PUBMED (PM) and Google Scholar (GS) were systematically searched between January 1st 1966 and March 31st 2023. Search terms included: Blalock, Taussig, shunt, pulmonary artery and Tetralogy of Fallot. Only full-text papers that measured pre-BTTS and post-BTTS BPA sizes using the Nakata Index or z-scores were included. Results: Twenty full-text articles (718 patients) were included in this review. When the pre-BTTS right pulmonary artery (RPA) z- score that corresponds to the mean pre-BTTS NI was considered for each article, Nineteen out of 20 articles (717 patients) had normal sized RPAs (i.e. their z-scores fell within the normal distribution). Although BPAs were found to grow post BTTS, available evidence suggest that most of the growth (67%) was due to BPA distension. A longer duration of BTTS did not increase BPA growth. Conclusion: The evidence available suggests that the modified BTTS does not produce sufficient ‘catch-up’ growth of hypoplastic BPAs to facilitate total correction or definitive palliation via the Fontan pathway.

Keywords: Blalock Taussig Thomas shunt pulmonary artery growth