Predicting the identity of decompressing veins after cavopulmonary anastomoses

D veins are an important cause of unanticipated cyanosis after cavopulmonary anastomosis (CPA). Venous connections between the superior and inferior vena caval pathways result in cyanosis after bidirectional CPA (hemi-Fontan and bidirectional Glenn), whereas connections between the systemic and pulmonary venous pathways lead to cyanosis after either bidirectional CPA or total cavopulmonary connection (Fontan operation). Previous studies have focused on hemodynamic settings in which decompressing channels are likely to occur after bidirectional CPA. However the spectrum of anatomic variations resulting in significant venous decompression after total as well as superior cavopulmonary connections has not been well characterized. In this study, we defined the anatomy of significant decompressing veins occurring after CPA, determined the incidence of significant decompressing veins by reviewing angiograms in all patients after CPA, and determined whether cardiac anatomy or clinical parameters were predictive of decompressing venous anatomy. The cardiology database from The Children’s Hospital of Philadelphia was reviewed to identify patients with CPAs who had undergone cardiac catheterization between January 1987 and January 1998. Patients whose angiograms could be obtained and were of adequate quality for interpretation were included in the analysis. Echocardiographic diagnoses were reviewed. The anatomy of the underlying heart defect was classified into 1 of 4 categories: (1) hypoplastic left heart syndrome, (2) other functional single right ventricle (including double-outlet right ventricle), (3) functional single left ventricle (including tricuspid atresia and pulmonary atresia), and (4) heterotaxy syndrome. Hemodynamic information including arterial oxygen saturation, pulmonary artery pressures, and ventricular end-diastolic pressures was recorded. Angiograms were reviewed noting anatomy and size of decompressing veins. Magnification correction was based on the known diameter of the angiographic catheter. Decompressing vessels were deemed significant if they were 3 mm in diameter or associated with arterial oxygen saturation 1 SD below the mean for each group (superior or total CPA). In many patients, right azygos veins were intentionally left patent by the surgeon at the time of bidirectional CPA. The significance of decompressing right azygos veins was determined solely by saturation criteria. Finally, in patients with other sources of arterial desaturation after total cavopulmonary connection (baffle leak, fenestration, or partial hepatic vein exclusion), only size was considered in determining the significance of decompressing veins. Differences between groups were evaluated by Student’s t test or Wilcoxon rank-sum test for numerical data, and chi-square distribution for categorical variables. A p value 0.05 was considered statistically significant. Five hundred fifty patients were identified with CPA. Angiograms adequate for review were obtained for 298 of these patients. Hypoplastic left heart syndrome was present in 170 patients (47%), single left ventricle in 101 (28%), single right ventricle in 60 (17%), and heterotaxy syndrome in 32 (8%). Data were collected on 208 patients who had undergone hemi-Fontan or bidirectional Glenn procedures. The median age at catheterization was 19 months (range 4 months to 17 years). Thirty-three of these patients (16%) had significant decompressing veins. Pulmonary artery pressures were higher, and (partially by definition) arterial oxygen saturations were lower in patients with decompressing veins (p 0.05; Table 1). Four types of decompressing veins occurred after bidirectional CPA. Most common were azygos connections; 19 cases accounted for 58% of the total. This type included azygos veins to either the right or left superior vena cava (SVC), hemiazygos veins, and accessory hemiazygos veins (Figure 1A). Left SVC decompressing to a coronary sinus occurred in 8 paFrom the Department of Pediatrics, University of Pennsylvania School of Medicine and Division of Cardiology, The Children’s Hospital of Philadelphia, Philadelphia, Pennsylvania. Dr. Rome’s address is: Division of Cardiology, The Children’s Hospital of Philadelphia, 34th Street and Civic Center Boulevard, Philadelphia, Pennsylvania 19104. E-mail: rome@email.chop.edu. Manuscript received February 19, 2001; revised manuscript received and accepted July 23, 2001. TABLE 1 Hemodynamic Data from Patients With Bidirectional Cavopulmonary Anastomosis