Right Ventricular Outflow Tract Stenting as an Option to Blalock-Taussig Shunt for Tetralogy of Fallot

Abstract

Tetralogy of Fallot (TOF) is a complex cardiac condition that includes a wide anatomical spectrum. Surgical repair may have an uneventful outcome between 6 months and the first year of life in most patients with favorable anatomy (e.g. adequate size of branch pulmonary arteries). However, management remains a challenge in symptomatic patients that present early in life, often due to a more severe involvement of right sided obstruction. In this setting, cyanosis becomes evident as a consequence of the progressive narrowing of the pulmonary infundibulum as well as an increased right ventricular stroke volume that faces a semi-fixed resistance and directs flow towards the systemic circulation. In addition, these patients often show underdevelopment of right-sided structures, including a smaller pulmonary annulus, a short and tapered main pulmonary artery, as well as variable degree of diffuse hypoplasia and/or stenosis of the pulmonary arteries. (1) Thus, it is not surprising that most of these children exhibit early progressive cyanosis and are at potential risk of “hypoxic spells” that require early medical stabilization with prostaglandin infusion to maintain arterial duct patency until a more definitive therapy can be established. Today, although some selected centers advocate for early surgical repair within the first 3 months of life (provided anatomical features are considered favorable), many countries (including Latin America) continue to support an initial palliative approach. Creation of a systemic-to-pulmonary shunt, usually a modified BlalockTaussig type (MBTS) followed by complete repair at a later stage is still the most adopted strategy in many centers around the world. Far from being considered an ideal palliative measure, a MBTS can result in disproportionate growth of the pulmonary arteries or stenosis of the involved pulmonary branch that may hinder results at the time of complete repair. (2, 3) Furthermore, according to a recent publication, shunt thrombosis or pulmonary