Unifocalization for pulmonary atresia with ventricular septal defect

Abstract

n this issue of The Annals, Iyer and Mee [l] report their I experience with the staged repair of pulmonary atresia, ventricular septal defect, hypoplastic pulmonary arteries, and systemic to pulmonary collateral arteries. Roughly, half of the patients enrolled in their protocol underwent final, complete repair of an anomaly that traditionally has been considered beyond surgical help, except for various palliative procedures. Their experience with this difficult group of patients is similar to that reported by us [2] and by Sawatari and co-workers [3]. The basic concepts used in this staged approach include (1) restoration of flow to the hypoplastic central pulmonary arteries by means of a systemic to pulmonary artery shunt or a conduit from the right ventricle to the pulmonary arterial confluence and (2) correction of arborization abnormalities of the central pulmonary arteries using pulmonary arterial segments supplied by large, discrete systemic collateral arteries (unifocalization procedures). Indeed, our experience suggests that patients with hypoplasia of the central pulmonary arterial confluence can become candidates for complete intracardiac repair See also page 65. simply by right ventricular outflow reconstruction [4-81. This maneuver appears to suffice in about 50% of the cases [7, 81. The limiting factor in the remaining patients was limited arborization of the central pulmonary arteries. The unifocalization procedures are designed to improve the arborization pattern of the central pulmonary arteries. The use of systemic collateral arteries for this purpose required a conceptual change. In the past, these vessels were considered to be bronchial arteries with vague, ill-defined connections to the pulmonary arterial segments [9, lo]. The contributions of Haworth, Macartney, Thiene, Faller, and their co-workers [ll-151 indicated that these arteries are essentially arterial conduits connecting the systemic circulation to the true pulmonary arterial segments. This allows their use for the purposes of increasing pulmonary arterial runoff from the central pulmonary arteries. Systemic collateral arteries that connect freely with the central pulmonary arteries (communicating) can be interrupted, whereas those that do not have unrestricted connections with the central pulmonary arteries (noncommunicating) must be detached from their origin, mobilized, and connected surgically to the central pulmonary arteries or their branches. Address reprint requests to Dr Puga, Mayo Clinic, 200 First St SW, Rochester, MN 55905. Although the report by Iyer and Mee [l] concentrates on patients with hypoplastic confluent pulmonary arteries, we have also successfully repaired patients with absent central pulmonary arteries, in whom the pulmonary arterial circulation arborization is entirely provided by systemic collateral arteries. Such cases demand staged unifocalization and prosthetic replacement of the main and unbranched portion of the pulmonary arteries [2, 151. Similar cases were reported by Sawatari and colleagues I entirely agree with Iyer and Mee that the future of these complex surgical repairs remains uncertain. Important questions must be asked regarding the long-term behavior of conduits and anastomoses to the pulmonary arteries, and regarding the fate of the pulmonary arterioles. Although the limitations of prosthetic conduits of all types are well understood, of greater concern is the adequacy of the right ventricular decompression after complete intracardiac repair. Persistent stenosis at numerous sites of the reconstructed pulmonary vasculature often results in less than ideal peak right to left ventricular systolic ratios. In addition, there is the distinct possibility of pulmonary vascular obstructive disease affecting in variable degree the different pulmonary arterial segments. This appears as a distinct possibility owing to the uneven perfusion of the different pulmonary arterial segments. Clearly, long-term follow-up of these patients is indispensable and, when available, will be determinant in assessing the value of these complex surgical endeavors. Can these patients be better served by these techniques or by the radical procedures involved in cardiopulmonary transplantation? Complex forms of pulmonary atresia with ventricular septal defect remain among the very few congenital heart malformations for which the search for a satisfactory surgical solution continues. Efforts such as the one described by Iyer and Mee will certainly contribute to the proper treatment of this difficult group of patients. [31.