RESULTS
Thirteen patients (81%) had situs solitus and 3 (19%) patients had situs inversus. We encountered double inlet ventricles in 6 of the cases (37%). Three patients had tricuspid and two patients had mitral atresia. In thirteen out of 16 patients (81%), one of the ventricles were hypoplastic, right ventricle in 7 and left ventricle in 6 cases. In 3 cases, both of the ventricles were developed and the indication for Fontan palliation were congenitally corrected transposition of the great arteries (c-TGA) (pt. no 5 and 9) and a criss-cross atrioventricular (AV) connection in the setting of double outlet right ventricle (DORV) and a large ventricular septal defect (VSD) (pt. no 6).
Stage-1 palliation was deemed necessary in 8 of the cases (50%). These interventions included balloon atrial septostomy or surgical atrial septectomy in order to increase mixing at the atrial level, pulmonary banding in order to control pulmonary arterial pressure and flow and modified Blalock-Taussig shunt (MBTS). Patient no. 6 had a history of supramitral membrane resection along with pulmonary artery banding and atrial septectomy. All of the surgical atrial septectomy procedures were performed as concomitant interventions, none of the patients were operated on for surgical atrial septectomy alone. Five patients (31%) had a history of systemic to pulmonary shunt surgery as stage I palliation (pt. no 4,5,8,13 and 14). In patient no.13, early postoperative shunt occlusion was encountered and primary surgical thrombectomy was performed. In all other cases, MBTS grafts were primarily patent until surgical closure at the following stages.
Stage-2 palliation was performed in all cases which included superior cavopulmonary anastomosis and concomitant procedures, which included atrial septectomy, pulmonary banding, pulmonary artery patch augmentation and atrioventricular valve repair. The bidirectional Glenn procedure was bilateral in patients 10, 14 and 15. Prior shunts were clipped or divided at stage II, except for two cases. In patient no.8, MBTS was still functional as an additional pulmonary blood flow source and in pt. no 5, there was an unintentional residual shunt flow at the time of stage III. Both of these cases were operated on at other cardiac surgery centers at stage II palliation and these shunts were closed at stage III.
Stage III Fontan completion was achieved with apolytetrafluorethylene (PTFE) tubular conduit (GORE-TEX, W.L. Gore and Associates Ltd., Livingston, Scotland) at sizes between 16 mm and 22 mm. Extracardiac Fontan procedure was performed in all cases, except for pt. no 11 and 14 where an intra-extra cardiac conduit was interposed. Concomitant procedures at stage III included DeVega tricuspid annuloplasty, pulmonary artery reconstruction, atrial re-septectomy and shunt closure. Fenestration was performed in 4 cases (25%) (pt. no 1,4,11 and 12). At the time of stage III, all of the patients underwent preoperative cardiac catheterization under local anesthesia and sedation. In pt. no7, a major aortopulmonary collateral artery was occluded via femoral route before stage III completion. We did not encounter any inferior vena cava interruption and azygos vein continuity. The mean pulmonary artery (Nakata) index was calculated as 293 ± 72 mm2/m2 (range 171 to 456 mm2/m2). Interstage period, i.e. the time between stage II and stage III operations were 4 ± 2.6 years (range 1 to 10 years). The stages of Fontan circulation and concomitant procedures are summarized in table-3.
The mean preoperative MPAP measured at the catheterization lab and at the operation room were 17.5 ± 2.1 mmHg and 16.5 ± 1.8 mmHg, respectively. The central venous pressure (measured via internal jugular vein catheter) that was recorded at the initiation of Fontan completion in the operation room represented the MPAP, since all the patients had a prior cavopulmonary anastomosis. All of the patients had antegrade pulmonary blood flow except for the patients no. 4 and 5 who had atresia of the pulmonary valve. The antegrade pulmonary blood flow was diminished either by native valvular or subvalvular pulmonary stenosis and/or a pulmonary band placed at the time of bidirectional Glenn procedure in 13 of the cases, except patient no. 10, who had a double inlet left ventricle with restrictive VSD. The mean pulmonary arterial gradient (except pt. no 4, 5 and 10) was 73.5 ± 10.2 mmHg (range 50 to 86 mmHg) at the time of Fontan operation. Postoperative MPAP and arterial oxygen saturation levels were 11.2 ± 2.8 mmHg (range 4 to 15 mmHg) and 97.8 ± 2 (range 93 to 100), respectively. The preoperative and postoperative MPAP values of the patients following the Fontan completion are presented in figure-1.