PREVALENCE AND RISK-FACTORS FOR AORTOPULMONARY COLLATERAL VESSELS AFTER FONTAN AND BIDIRECTIONAL GLENN PROCEDURES

Objectives. The purpose of this study was to evaluate the prevalence of and risk factors for aortopulmonary collateral vessels in patients who have undergone a bidirectional Glenn or Fontan procedure, or both. Background. Aortopulmonary collateral vessels are frequently observed angiographically in patients after a bidirectional Glenn or Fontan procedure. These vessels may provide a source of pulmonary blood flow competitive with anterograde cavopulmonary flow. Methods. We performed a retrospective study of all patients (n = 196) who underwent catheterization between January 1, 1988 and February 29, 1992 (n = 268) after bidirectional Glenn or Fontan procedures and reviewed clinical, hemodynamic and angiographic phone data. Results. Collateral vessels were diagnosed in 36% of patients. Patients who underwent the bidirectional Glenn procedure were more likely to have collateral vessels than patients who underwent the Fontan procedure (65% vs. 30%, respectively; p < 0.0001). Patients with a history of a Blalock-Taussig shunt were more likely to have collateral vessels than those without (50% vs. 24%, respectively; p = 0.0006). Discretely identifiable collateral vessels were measurable in 54 (20%) of 268 catheterizations. The total estimated cross-sectional area of these vessels averaged 10.7 7.2 mm2. In patients who underwent the bidirectional Glenn procedure, a step-up in oxygen saturation from the superior vena cava to the distal pulmonary arteries or an upper lobe filling defect, or both, on pulmonary angiogram predicted total estimated cross-sectional area of collateral vessels. Most collateral vessels originated from the internal mammary arteries (34%) and the thyrocervical trunks (22%). Only 9% of collateral vessels arising from the brachiocephalic vessels were visualized by aortogram; the remainder required selective angiography in the subclavian or more distal arteries. Conclusions. Aortopulmonary collateral vessels are common after bidirectional Glenn and Fontan procedures. Aortograms often fail to diagnose their presence. The left to right shunt carried by these vessels is associated with a step-up in oxygen saturation in the distal pulmonary arteries. The clinical significance and indications for closure of these vessels are not known.