The real fate of pulmonary arteries after bidirectional superior cavopulmonary anastomosis: is there a need for concern?

Controversy remains about the growth of the pulmonary arteries following a bidirectional superior cavopulmonary anastomosis in children with complex c yanotic congenital cardiac malformations. This is partially due to the morp hological heterogeneity of the patients, and partially due to methodologica l differences in series published so far. It is further complicated by the variable use, in different centres, of additional sources of pulmonary bloo d flow. We believe that the fate of these arteries preoperatively is signif icantly influenced by the amount of pulmonary blood flow and the initial si ze of the arteries. Separate assessment of the pulmonary arterial developme nt postoperatively is recommended for those who, initially, had relatively small as opposed to larger than normal pulmonary arteries. Measurement of t he diameters of both pulmonary arteries just prior to their first point of branching, together with the use of Z-score evaluation rather than the Naka ta index, is discussed. It remains to be established whether, over time, th e bidirectional cavopulmonary anastomosis is effective in developing adequa tely the pulmonary arteries in preparation for an ultimate total cavopulmon ary connection, or even as isolated long-term palliation. A prospective, mu lti-institutional study involving sequential non-invasive assessment of pul monary arterial development (using, for example, magnetic resonance imaging ) is required to solve the outstanding problems.