Systemic Venous Collateral Channels Causing Desaturation After Bidirectional Cavopulmonary Anastomosis: Evaluation and Management

Objectives. We sought to characterize the frequency, anatomic details and factors associated with the development of collateral channels between the superior and inferior ven caval systems after bidirectional cavopulmonary anastomosis. Background. It is well known that systemic venous collateral channels often develop in patients who have undergone classic Glenn shunt or bidirectional cavopulmonary anastomosis and that such collateral channels can lead to profound systemic desaturation. However, there have been few reports focusing on this problem. Methods. Fifty-four patients (median age 1.4 years) who underwent bidirectional cavopulmonary anastomosis and had preoperative and postoperative angiograms available for review were studied retrospectively. Postoperative connections between the superior and inferior ven caval systems were identified and measured. Sites of collateral origin and entry from the superior and inferior venous systems, as well as the course taken in between, were recorded. Results. At follow-up angiography performed 17 days to 46 months postoperatively, total of 31 venous collateral channels were observed in 18 patients with wide variety of primary morphologic diagnoses. The majority of these collateral channels (80%) originated from the brachiocephalic vein or its junction with the superior ven cava, and over half of them drained below the diaphragm. In patients who developed venous collateral channels, the mean transpulmonary pressure gradient early after bidirectional cavopulmonary anastomosis was higher (p = 0.005), and mean arterial oxygen saturation at follow-up was lower (p = 0.009). There were trends toward higher superior ven caval pressure early after the operation and at follow-up in patients with collateral channels and higher likelihood of absent upper lobe pulmonary blood flow in these patients. Successful coil embolization of 10 collateral channels was performed in six patients, with median increase in arterial oxygen saturation of 16%. Conclusions. Angiographically detectable systemic venous collateral channels develop after bidirectional cavopulmonary anastomosis in substantial number of patients (33% in the present series) with variety of forms of functional univentricular heart. Patients with venous collateral channels can be treated successfully with coil embolization, but the indications for embolization will depend on individual circumstances.