Lateral Tunnel Versus Extracardiac Conduit Fontan Procedure: A Concurrent Comparison

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1 Lateral Tunnel Versus Extracardiac Conduit Fontan Procedure: A Concurrent Comparison S. Prathap Kumar, FRCS, Catherine S. Rubinstein, FNP, Janet M. Simsic, MD, Ashby B. Taylor, MD, J. Philip Saul, MD, and Scott M. Bradley, MD Divisions of Cardiothoracic Surgery, Pediatric Cardiology, Medical University of South Carolina, Charleston, South Carolina Background. The aim of this study was to compare the outcomes of the lateral tunnel (LT) and extracardiac conduit (ECC) Fontan procedures at a single institution over the same time period. Methods. From November 1995 through October 2002, 70 Fontan procedures were performed: 37 LT and 33 ECC. All were fenestrated; 96% were staged with a prior superior cavopulmonary connection. Compared with the ECC patients, the LT patients were younger ( vs years; p 0.01), had a higher incidence of hypoplastic left heart syndrome (57% vs 21%; p < 0.01), and a longer aortic cross-clamp time (55 13 vs min; p < 0.01). Weight, gender, preoperative cardiac catheterization values, and cardiopulmonary bypass time did not differ between the two groups. Results. Operative mortality was 2.8%, 1 patient in each group (p 1.0). Over the first 24 hours following operation the mean Fontan pressure, transpulmonary gradient, and common atrial pressure did not differ between LT and ECC patients. The median duration of mechanical ventilation (LT 12 vs ECC 18 hours), intensive care unit stay (LT 2 vs ECC 3 days), chest tube drainage (LT 10 vs ECC 8 days), and hospital stay (LT 11 vs ECC 12 days) did not differ. The ECC patients had a higher incidence of sinus node dysfunction both in the postoperative period (27% vs LT 8%; p 0.09), and persisting at hospital discharge (10% vs LT 0%; p 0.02). Mean follow-up was years in LT, and years in ECC patients (p 0.2). There was one late death. Actuarial survival at 5 years is 97% for LT, and 91% for ECC patients (p 0.4); 96% of patients are in NYHA class I, and 4% in class II, with no difference between groups. Sinus node dysfunction was seen during follow-up in 15% LT vs 28% ECC patients (p 0.2). Conclusions. The LT and ECC approaches had comparable early and mid-term outcomes, including operative morbidity and mortality, postoperative hemodynamics, resource use, and mid-term survival and functional status. ECC patients had a higher incidence of sinus node dysfunction early after operation. (Ann Thorac Surg 2003;76: ) 2003 by The Society of Thoracic Surgeons Presented at the Forty-ninth Annual Meeting of the Southern Thoracic Surgical Association, Miami Beach, FL, Nov 7 9, Address reprint requests to Dr Bradley, Division of Cardiothoracic Surgery, Medical University of South Carolina, 96 Jonathan Lucas St, Charleston, SC 29425; bradlesm@musc.edu. Staged palliation culminating in a successful Fontan procedure is the current surgical goal for most patients with a functional single ventricle. Since its introduction in 1968, the Fontan procedure has undergone many modifications [1]. At present, two modifications in common use are the lateral tunnel (LT) [2 6] and extracardiac conduit (ECC) [7 9]. The LT, introduced in 1987 [10 12], involves placement of an intraatrial baffle. Although excellent mid- and long-term results of the LT have been documented, its risks include postoperative atrial arrhythmias [13 15]. The ECC, introduced in 1990 [16], minimizes or avoids atrial suture lines and atrial distention. These characteristics have the theoretical advantage of decreasing postoperative atrial arrhythmias, and improving outcome. Most institutions and surgeons have focused on a single technical approach to the Fontan procedure. As a consequence, comparison of the LT and ECC has required comparing results from different institutions, frequently from different time periods. Direct comparisons of the LT and ECC at a single institution have been limited in number [17, 18]. Over the last 7 years at the Medical University of South Carolina, the LT and ECC have been used concurrently in approximately equal numbers of patients. The aim of this study was to compare the early and mid-term outcome of the two approaches, including postoperative hemodynamics, resource utilization, arrhythmias, and functional status. Material and Methods This study was approved by the Institutional Review Board of the Medical University of South Carolina. From November 1995 through October 2002, 77 consecutive Fontan procedures were performed at the Medical University by a single surgeon (S.M.B.). Seven were conversions of previous atriopulmonary connections to total cavopulmonary connections, and were excluded from this analysis. No other patient was excluded. Of the 70 remaining Fontan procedures, 37 were LT and 33 ECC. The decision between the LT and ECC approach was made based on patient anatomic suitability and surgeon preference, without randomization. Hospital, operative, 2003 by The Society of Thoracic Surgeons /03/$30.00 Published by Elsevier Inc doi: /s (03)

2 1390 KUMAR ET AL Ann Thorac Surg LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN 2003;76: and clinic records were reviewed. Hemodynamic values for the first 24 hours after operation were determined from intensive care unit (ICU) records. Fontan (central venous) pressure was typically measured via an internal jugular venous line ending in the superior vena cava, and common atrial pressure via a transthoracic line placed in the operating room. Transpulmonary gradient was derived as Fontan pressure minus common atrial pressure. Data review specifically included all 12-lead electrocardiagram (ECG) and 24-hour Holter recordings obtained either in the hospital, or during follow-up. The 24-hour Holter recordings were obtained in the hospital in 7 of 37 (19%) LT vs 6 of 33 (18%) ECC patients (p 1.0); 24-hour recordings were obtained during follow-up in 14 of 36 (38%) LT vs 17 of 32 (53%) ECC patients who survived operation (p 0.1). Sinus node dysfunction was defined as a need for temporary atrial pacing, sinus bradycardia with a heart rate greater than 2 standard deviation (SD) less than the age-adjusted mean, or junctional escape rhythm. Sinus node dysfunction identified during the operative hospitalization was classified as transient if it resolved by the time of hospital discharge [14]. Sinus node dysfunction identified during follow-up was classified as transient if it resolved on subsequent recordings. Supraventricular tachycardia was defined as a nonsinus, narrow complex tachycardia documented on 12-lead ECG or 24-hour Holter recording. This included junctional ectopic tachycardia and intraatrial reentry tachycardia (atrial flutter). The results of the follow-up 24-hour Holter recordings in several of these patients were included in a previous publication [19]. In addition to reviewing clinic notes, follow-up was directly obtained by phone from patients families by a nurse practitioner (C.S.R.) between June and October This follow-up call included a questionnaire covering functional status, complications, and medications. Follow-up was complete in all patients. Due to concerns over cost and potential homograft shrinkage over time, PTFE grafts are currently used. A fenestration was placed by side-to-side anastomosis of the ECC to the atrium, or by interposition of a small PTFE tube graft between the ECC and the atrium. The fenestrations included a subcutaneous snare, which can be utilized to close the fenestration 6 to 12 months following the Fontan procedure. Modified ultrafiltration was used in all patients. Patient size was not specifically considered for LT, although the ECC was generally performed at a patient weight of 15 kg to accommodate a larger conduit [7, 8]. Concomitant procedures in 25 patients included atrioventricular valve repair (7 patients), main pulmonary artery division (5 patients), pulmonary artery stent dilation (4 patients), branch pulmonary artery stenosis repair (3 patients), right atrial maze (1 patient), atrial septectomy (1 patient), pulmonary vein repair (1 patient), superior vena cava stenosis repair (1 patient), and pacemaker generator change (1 patient). Bilateral pleural chest tubes were placed in all patients and managed by a protocol in which they were removed once drainage was less than 2 ml/kg per day for each tube. It has been our experience that this protocol minimizes the need for chest tube reinsertion after removal. Statistics Data from the LT and ECC groups were compared using unpaired Student s t test, Fisher s exact test, or Chisquare test, as appropriate. Postoperative hemodynamic data were analyzed by repeated measures analysis of variance; multiple comparison testing was by the Student-Newman-Keuls test. Data are shown as mean SD, or median (range). Statistical significance was defined as p less than Actuarial survival curves were generated using SPSS version for Windows (SPSS Inc, Chicago, IL). Surgical Techniques All Fontan operations were performed via a median sternotomy and utilized cardiopulmonary bypass. Aortic cross-clamping was used in all LT patients and 17 ECC patients to allow concomitant intracardiac procedures, or ensure adequate fenestration. Myocardial protection was by cold, blood cardioplegia administered antegrade. In the LT procedure, a polytetrafluoroethylene (PTFE, Gore- Tex; W.L. Gore & Associates, Flagstaff, AZ) baffle was sewn inside the right atrium to route inferior vena caval blood up the lateral aspect of the atrium to the superior cavopulmonary junction [2, 11]. The baffle was sutured posteriorly to the edge of the atrial septal defect, and anteriorly to the atrial wall, or the edge of the atriotomy. A fenestration was placed in one of the suture lines, or in the baffle. The ECC was performed by placing a tube graft between the divided inferior vena cava and the central pulmonary arteries [7, 8]. The tube graft consisted of an aortic homograft 21 to 24 mm in diameter (in 21 patients), or a PTFE graft 18 to 22 mm in diameter (in 12 patients). Homografts were used in earlier patients, primarily for ease of suturing to the pulmonary arteries. Results Patients There were several differences between the patients in the LT and ECC groups. The LT patients were significantly younger at the time of surgery (Table 1). A significantly greater proportion of the LT patients had hypoplastic left heart syndrome, 57% compared with 21% of the ECC patients (Table 1). Other anatomic diagnoses, as well as ventricular morphology, did not differ between the groups (Table 1). All patients underwent cardiac catheterization prior to the Fontan procedure; the mean values of the variables measured at catheterization were essentially identical in the two groups (Table 1). Sixty-seven of 70 Fontan procedures (96%) were staged with a prior bidirectional superior cavopulmonary connection. The technical approach to the superior cavopulmonary connection differed between the two groups (Table 2). Among the 36 staged LT patients, the prior cavopulmonary connection consisted of a hemi-fontan procedure in all [2, 4, 5]. Among the 31 staged ECC patients, the cavopulmonary connection consisted of a

3 Ann Thorac Surg KUMAR ET AL 2003;76: LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN Table 1. Patient Characteristics Patients Age (years) a Weight (kg) Sex Male 22 (59%) 22 (67%) 0.6 Female 15 (41%) 11 (33%) Anatomic Diagnosis HLHS 21 (57%) 7 (21%) 0.01 a Tricuspid atresia 6 (16%) 8 (24%) 0.6 Heterotaxy 2 (5%) 6 (18%) 0.1 DILV 2 (5%) 2 (6%) 1.0 Other 6 (16%) 10 (30%) Morphologic Left ventricle 15 (40%) 17 (52%) 0.6 Right ventricle 22 (60%) 16 (48%) Preoperative cardiac catheterization Pressure (mmhg) Pulmonary artery Common atrium Transpulmonary gradient Ventricular end-diastolic pressure Oxygen saturation (%) Aorta Mixed venous Qp:Qs Pulmonary arteriovenous malformations 1 (3%) 2 (6%) 0.6 a p 0.05 LT vs ECC. DILV double-inlet left ventricle; ECC extracardiac conduit; HLHS hypoplastic left heart syndrome; LT lateral tunnel; Qp:Qs pulmonary-to-systemic blood flow ratio. Table 2. Previous Operations 1391 Patients Superior cavopulmonary 36 (97%) 31 (94%) 0.6 connection Hemi-Fontan 32 0 Hemi-Fontan Left 4 0 BDG BDG 0 25 Bilateral BDG 0 6 None 1 2 Norwood procedure 24 (65%) 10 (30%) 0.01 a Systemic pulmonary 5 (14%) 18 (54%) 0.01 a shunt Damus-Kaye-Stansel Neonatal Ebstein s Palliation (Starnes) AV valve repair AV valve closure Atrial septectomy Pulmonary artery band Ascending aortic reconstruction Pulmonary artery unifocalization Coarctation repair Division main pulmonary artery TAPVR repair ECMO Permanent pacemaker a p 0.05 LT vs ECC. AV atrioventricular; BDG bidirectional Glenn shunt; ECC extracardiac conduit; ECMO extracorporeal membrane oxygenation; LT lateral tunnel; TAPVR total anomolous pulmonary venous return. bidirectional Glenn shunt in all [7, 8]. Four LT and 6 ECC patients with bilateral superior vena cavae underwent an additional contralateral bidirectional Glenn shunt (Table 2). One patient in each group had an interrupted inferior vena cava with azygous continuation, making the superior cavopulmonary connection a functional Kawashima procedure. Other previous operations are listed in Table 2. The LT patients had a significantly higher incidence of prior Norwood procedures (65% vs 30%), whereas the ECC patients had more commonly undergone a previous isolated systemic-pulmonary shunt. The mean cardiopulmonary bypass time did not differ between groups (Table 3). Aortic cross-clamping was used in all LT patients and 52% of ECC patients. The mean cross-clamp time was significantly longer in the LT group (Table 3). Fenestrations were placed in all 70 patients. Early Outcome Overall operative mortality was 2 of 70 patients (2.8%). One LT patient, with preoperative pulmonary arteriovenous malformations, died of low cardiac output and sepsis. One ECC patient died due to mediastinitis and ECC thrombosis. An additional ECC patient underwent postoperative Fontan takedown to a bidirectional Glenn shunt, due to thrombotic complications of heparininduced thrombocytopenia. He also sustained a stroke due to carotid artery thrombosis. Other complications included early reoperations to close or revise a fenestration in 3 ECC patients, re-exploration for bleeding in 1 ECC patient, and mediastinal debridement for mediastinitis in 1 ECC patient. No other patient had recognized thrombosis in the Fontan pathway. Table 3. Operative Data Cardiopulmonary bypass Patients 37 (100%) 33 (100%) Time (minutes) Aortic cross-clamp Patients 37 (100%) 17 (52%) 0.01 a Time (minutes) a Fenestration 37 (100%) 33 (100%) a p 0.05 LT vs ECC. ECC extracardiac conduit; LT lateral tunnel.

4 1392 KUMAR ET AL Ann Thorac Surg LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN 2003;76: Over the first 24 hours following operation, the mean Fontan pressure and transpulmonary gradient were similar in the two groups (Figs 1A and 1C). Common atrial pressure tended to be slightly higher in the LT patients than the ECC patients, although this difference did not achieve statistical significance (Fig 1B). In the group as a whole, the mean Fontan pressure remained constant over the first 24 hours, while the common atrial pressure tended to increase, and the transpulmonary gradient to decrease (Fig 1). This trend was similar in both LT and ECC patients. Resource utilization was also similar in the LT and ECC patients (Table 4). The median durations of mechanical ventilation, ICU stay, chest tube drainage, and hospital stay did not differ between the two groups. Postoperative Arrhythmias Four patients were in a rhythm other than sinus rhythm prior to the Fontan procedure. One LT patient had a permanent pacemaker placed for complete heart block following a neonatal Starnes procedure for Ebstein s anomaly. Three ECC patients had intermittent junctional rhythm or sinus bradycardia; one of these had a permanent pacemaker in place. Among the 66 patients in sinus rhythm at the time of the Fontan procedure, postoperative sinus node dysfunction was seen more commonly among ECC than LT patients (Table 5). At the time of hospital discharge 5 ECC patients, and no LT patients, had persistent sinus node dysfunction (Table 5). Two of these 5 patients underwent placement of a permanent atrial pacemaker for slow junctional rhythm prior to hospital discharge. Among the 8 patients with heterotaxy, 1 LT and 2 ECC patients had transient postoperative sinus node dysfunction; none had persistent sinus node dysfunction. Follow-Up Follow-up was complete in all patients and was of similar duration in the two groups (Table 6). One patient, who was not a candidate for heart transplantation, died 2.5 years after ECC due to deteriorating ventricular function. Actuarial survival at 5 years is 97% for LT, and 91% for ECC patients (p 0.4, Fig 2). Protein-losing enteropathy developed in 2 LT patients. Both are currently responding to medical treatment. Overall, 96% of patients are in NYHA class I, and 4% in class II, with no difference between LT and ECC patients (Table 6). Among the 65 survivors followed for more than 1 month, aspirin is taken by 61 (94%), an angiotensinconverting enzyme inhibitor by 23 (35%), furosemide by 10 (15%), digoxin by 8 (12%), and coumadin by 2 (3%). There is no difference in medication use between the LT and ECC groups. Arrhythmias During Follow-Up Sinus node dysfunction was seen during follow-up in 15% of LT, and 28% of ECC patients, a difference that was not statistically significant (Table 6). Among the 5 patients with sinus node dysfunction at hospital discharge after Fontan procedure, 1 patient regained sinus rhythm during follow-up, 1 patient had intermittent sinus rhythm, and 3 patients had persistent sinus node dysfunction. Supraventricular tachycardia was infrequent, and did not differ between the two groups (Table 6). Two patients underwent late permanent pacemaker placement: 1 LT patient after late reoperation to enlarge a bulboventricular foramen at another institution, and 1 ECC patient for slow junctional rhythm. Comment The present study compares the results of LT and ECC Fontan procedures performed concurrently at a single institution over the last 7 years. The two approaches yielded very similar operative outcomes, resource use, early postoperative hemodynamics, and mid-term functional status. ECC patients had a higher incidence of sinus node dysfunction early after operation. The relative merits of the LT and ECC Fontan procedures have been described previously [7, 8, 11, 15]. Introduced in the mid-1980s [10 12], the LT provides a tubular path between the inferior vena cava and pulmonary arteries, consisting of a prosthetic baffle and a portion of the lateral atrial wall. The LT has favorable hydrodynamic characteristics, ensures unrestricted systemic and pulmonary venous pathways, minimizes atrial exposure to high pressure, and incorporates growth potential [11, 15]. It has been used in patients having a wide range of anatomic diagnoses with good early and mid-term results [2 6, 20]. Recently, excellent long-term outcome has been reported at a mean follow-up of 10.2 years [15]. The ECC, introduced in 1990 [16], consists of a tube graft between the inferior vena cava and pulmonary arteries. Like the LT, it provides a hydrodynamically efficient pathway for systemic venous flow. In addition, it leaves the entire atrium at low pressure, minimizes atrial suture lines, and can be performed without aortic crossclamping. It can also be performed without cardiopulmonary bypass [8]. The ECC does not incorporate growth potential, and has typically been performed in patients large enough to accept a graft adequate for an adult s inferior caval flow [7, 8]. Like the LT, the ECC has provided good early and mid-term results [7 9, 21]. In the current series, the LT and ECC had essentially identical operative outcomes. Overall operative mortality was 2.8%, and operative failure (mortality plus Fontan takedown) was 4.3%. These figures are similar to those in other recent series of Fontan procedures, with reported mortalities of 2% to 13% [3 8, 17, 22]. Operative mortality and failure did not differ between LT and ECC patients, although their low incidence makes them insensitive measures of outcome. We also found no differences between LT and ECC patients in duration of mechanical ventilation, ICU stay, chest tube drainage, or hospital stay. Another useful measure of outcome after a Fontan procedure is the postoperative Fontan pressure. This variable has been found to be predictive of early Fontan failure [15, 23]. In the current series there was no difference in the mean Fontan pressure of the LT and ECC patients over the first 24-hours after operation.

5 Ann Thorac Surg KUMAR ET AL 2003;76: LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN Fig 1. (A) Fontan pressure (p 0.9 LT versus ECC); (B) common atrial pressure (p 0.06 LT versus ECC); and (C) transpulmonary gradient (p 0.1 LT versus ECC) over the first 24 hours after Fontan procedure. *p 0.05 versus 0 hours for both groups; F lateral tunnel (LT); extracardiac conduit (ECC). (Postop postoperative.) 1393 Numerous studies have identified preoperative patient characteristics and operative variables that influence the risk of a Fontan procedure [3 6, 15, 17, 20, 22, 23]. In the current series, the LT patients were potentially at higher risk than the ECC patients. The LT patients were significantly younger at the time of Fontan procedure, had a higher incidence of hypoplastic left heart syndrome, and both a higher incidence and mean time of aortic crossclamping. Young age [20, 23] and a diagnosis of hypoplastic left heart syndrome [20] have been previously identified as risk factors for operative failure. However, both of these factors appear to have been neutralized in more recent series [4, 5]. Aortic cross-clamp time has also been identified as a risk factor for Fontan failure [4, 6, 23]. Despite their potentially higher risk, LT patients had early outcomes similar to ECC patients. This may be because other potentially more influential risk factors were similar in LT and ECC patients. These include pulmonary artery pressure [3 5, 20, 23], a morphologic right ventricle [6, 15], heterotaxy syndrome [6, 20, 23], cardiopulmonary bypass time [3, 4, 6, 17, 20], prior staging with a bidirectional superior cavopulmonary connection, and use of a fenestration [20, 22]. In this series fenestrations were placed routinely, for their potential beneficial effects on postoperative pleural effusions and risk of early failure [2, 5, 20, 22]. It has been our experience, and that of others [5], that preoperative hemodynamic variables are inaccurate predictors of postoperative effusions, and thus poor guides to selective fenestration. The LT and ECC approaches also provided comparable mid-term outcomes. Actuarial survival at 3 to 5 years was 97% for LT, and 91% for ECC patients, which was not statistically different. All surviving patients were in NYHA class I or II, with no differences between the two groups. This is in concert with other studies documenting good functional status at follow-up after a LT or ECC procedure [21, 24]. Two other recent publications provide information on LT and ECC procedures performed at a single institution. Gaynor and coworkers [5] reported the early outcome of 332 patients undergoing a Fontan procedure at the Children s Hospital of Philadelphia between 1992 and The LT was used in 281 patients, and ECC in 51 patients, with most of the ECC procedures being performed in the last 2 years of the series. The particular approach of a LT Fontan with a single-punch fenestration decreased the risk of death, prolonged pleural effusions, and prolonged hospitalization. However, as in our study, the type of Fontan (LT vs ECC) did not significantly affect operative mortality, or duration of postoperative pleural drainage [5]. Azakie and colleagues [17] reported a detailed comparison of 47 LT and 60 ECC procedures carried out between 1994 and 1998 at the Hospital for Sick Children (Toronto). Compared with the patients in our series, the Toronto patients had a lower overall incidence of hypoplastic left heart syndrome (19% vs 40%), a lower incidence of fenestration (80% vs 100%), and were older at the time of LT surgery (mean 4.0 vs 2.7 years). Although the LT approach was associated with a higher postoperative common atrial pressure, longer duration of mechanical ventilation, and longer ICU stay, the magnitude of these differences was small [17]. Overall, the operative outcome, resource use, and mid-term outcome of the LT and ECC in the Toronto series were very similar to those in our study. A notable difference between our results and those of the Toronto group was the incidence of arrhythmias in LT and ECC patients. Arrhythmias after a Fontan proce-

6 1394 KUMAR ET AL Ann Thorac Surg LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN 2003;76: Table 4. Resource Utilization Mechanical ventilation (hours) Intensive care unit stay (days) Chest tube drainage (days) Hospital stay (days) 12 (2 hours 21 days) Values are median (range). ECC extracardiac conduit; 18 (3 hours 21 days) dure may include sinus node dysfunction and supraventricular tachycardia. Sinus node dysfunction is thought to result from direct injury to the sinus node and/or its blood supply [25]. Atrial incisions, suture lines, increased pressure, and dilation may contribute to tachyarrhythmias [26]. In our analysis, sinus node dysfunction was observed more frequently among ECC than LT patients. This was true both in the postoperative period, and at mid-term follow-up, although the only difference that was statistically significant was persistent sinus node dysfunction at hospital discharge. Sinus node dysfunction, either in the hospital or during follow-up, led to the placement of permanent pacemakers in 3 patients in the ECC group, and none in the LT group. In contrast, the Toronto group observed sinus node dysfunction during the postoperative period in 45% LT vs 15% ECC patients [17]. The LT procedure was identified as a significant independent risk factor for early postoperative sinus node dysfunction. One potential reason for these differences between our findings and those of the Toronto group may be the approach taken to Fontan staging. In our series, LT patients were staged with a prior hemi-fontan procedure, and ECC patients with a bidirectional Glenn shunt. The Toronto patients were staged with a bidirectional Glenn approach in all patients except one [17]. The hemi-fontan procedure establishes a connection between the superior cavoatrial junction and pulmonary arteries [2]. Although the hemi-fontan involves surgery in the region of the sinus node, a subsequent LT Fontan procedure can be carried out without incisions, suturing, or redissection in the region of the sinus node and its Table 5. Postoperative Arrhythmias 0.5 2(1 21) 3 (2 57) (2 59) 8 (2 24) (6 60) 12 (6 57) 0.4 LT lateral tunnel. Sinus node dysfunction 3 (8%) 8 (27%) 0.09 Transient 3 (8%) 3 (10%) 1.0 Persistent 0 5 (17%) 0.02 a Permanent pacemaker 0 2 (7%) 0.2 Supraventricular tachycardia 1 (3%) a p 0.05 LT vs ECC. ECC extracardiac conduit; LT lateral tunnel. Table 6. Follow-Up Status Follow-up (years) Late mortality 0 1 (3%) 0.5 Protein-losing enteropathy 2 (6%) NYHA class I 34 (94%) 30 (97%) 1.0 II 2 (6%) 1 (3%) III IV 0 0 Sinus node dysfunction 5 (15%) 8 (28%) 0.2 Transient Persistent Supraventricular tachycardia 3 (9%) 1 (3%) 0.6 Permanent pacemaker ECC extracardiac conduit; LT lateral tunnel; NYHA New York Heart Association. blood supply [2]. In contrast, the LT after a previous bidirectional Glenn requires reconnecting the superior aspect of the atrium to the pulmonary arteries. This involves dissection, an incision, and suturing in the vicinity of the sinus node and artery, which may be obscured by scarring and absence of the superior cavoatrial junction as a landmark. These considerations may have contributed to the differing rates of early sinus node dysfunction among LT patients in the current report and the Toronto series (8% vs 45%). Other reports support a relationship between Fontan staging technique and sinus node dysfunction. Cohen and associates [18] analyzed early sinus node dysfunction after 46 LT and 30 ECC Fontan procedures. All LT patients had been staged with a hemi-fontan procedure, and all ECC patients with a bidirectional Glenn. The LT and ECC groups had an equal incidence of sinus node dysfunction (13%) at hospital discharge. Manning and coworkers [14] also examined early sinus node dysfunction in patients undergoing a staged Fontan procedure. Among 60 LT procedures staged with a previous bidirectional Glenn, sinus node dysfunction was observed in 56%, with 23% persisting at hospital discharge [14]. Thus, early sinus node dysfunction appears to be more frequent with a bidirectional Glenn-LT approach, than either a hemi-fontan LT or bidirectional Glenn-ECC approach. Early sinus node dysfunction may carry longterm implications, as it predicts late sinus node dysfunction [18], which is in turn associated with late supraventricular tachycardia [25, 26]. The incidence of supraventricular tachycardia after a LT or ECC Fontan operation has varied widely in other series. Early supraventricular tachycardia has been reported after 3% to 34% of LT procedures [13, 17, 25, 27], and after 5% to 31% of ECC procedures [8, 17, 21, 27, 28]. Azakie and colleagues [17] identified the LT, compared with the ECC, as a significant independent risk factor for early supraventricular tachycardia. The incidence of late supraventricular tachycardia after a LT procedure has been 0% to 22% [3, 13, 15, 25], and after an ECC 0% to 8% [7, 21, 27]. In the current study supraventricular tachycardia was infrequently observed in either the LT or ECC

7 Ann Thorac Surg KUMAR ET AL 2003;76: LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN Fig 2. Actuarial survival in LT and ECC patients. The p value is LT versus ECC (log rank test), and time 0 Fontan operation. (LT lateral tunnel; ECC extracardiac conduit.) patients, so that we cannot add information to the relative risks of the two techniques for tachyarrhythmias. A limitation of this study is the lack of randomization between the LT and ECC groups. We have tended to use a LT staged with a prior hemi-fontan procedure in patients with hypoplastic left heart syndrome. This approach may offer specific advantages in hypoplasts, such as routine augmentation of the left pulmonary artery at the time of the hemi-fontan, avoiding redissection of the pulmonary arteries behind the reconstructed neoaorta at the time of LT. It has provided excellent results in several large series of hypoplasts undergoing Fontan procedures [2, 4, 5]. On the other hand, the ECC provides advantages in patients with anomalies of systemic and pulmonary venous drainage, such as those with heterotaxy syndrome. Other limitations of this study are the retrospective design and the limited number of 24-hour Holter recordings, which are potential sources of underestimation of arrhythmias. Finally, the ECC was performed using cardiopulmonary bypass, and, in many patients, aortic cross-clamping. It is possible that a more aggressive approach to minimizing or avoiding both bypass and cross-clamping might improve ECC outcomes further [8]. In summary, this study documents the outcome of LT and ECC Fontan operations performed concurrently over the last 7 years at a single institution. The two approaches and comparable early and mid-term outcomes, including operative morbidity and mortality, postoperative hemodynamics, resource use, and mid-term survival and functional status. The ECC patients had a higher incidence of sinus node dysfunction early after operation. At present, the choice between the LT and ECC can be made based on patient anatomy, and surgeon preference. The authors would like to thank Martha R. Stroud, MS, for statistical assistance. References 1. Fontan F, Baudet E. Surgical repair of tricuspid atresia. Thorax 1971;26: Jacobs ML, Norwood WI Jr. Fontan operation: influence of modifications on morbidity and mortality. Ann Thorac Surg 1994;58: Kaulitz R, Ziemer G, Luhmer I, Kallfelz H. Modified Fontan operation in functionally univentricular hearts: preoperative risk factors and intermediate results. J Thorac Cardiovasc Surg 1996;112: Mosca RS, Kulik TJ, Goldberg CS, et al. Early results of the Fontan procedure in one hundred consecutive patients with hypoplastic left heart syndrome. J Thorac Cardiovasc Surg 2000;199: Gaynor JW, Bridges ND, Cohen MI, et al. 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8 1396 KUMAR ET AL Ann Thorac Surg LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN 2003;76: Airan B, Sharma R, Choudhary SK, et al. Univentricular repair: is routine fenestratiion justified? Ann Thorac Surg 2000;69: Knott-Craig CJ, Danielson GK, Schaff HV, Puga FJ, Weaver AL, Driscoll DD. The modified Fontan operation. J Thorac Cardiovasc Surg 1995;109: Gentles TL, Gauvreau K, Mayer JE Jr, et al. Functional outcome after the Fontan operatiion: factors influencing late morbidity. J Thorac Cardiovasc Surg 1997;114: Cohen MI, Wernovsky G, Vetter VL, et al. Sinus node function after a systematically staged Fontan procedure. Circulation 1998;98(Suppl II):II-352 II Fishberger SB, Wernovsky G, Gentles TL, et al. Factors that influence the development of atrial flutter after the Fontan operation. J Thorac Cardiovasc Surg 1997;113: Ovroutski S, Dahnert I, Alexi-Mseskishvili V, Nurnberg JH, Hetzer R, Lange PE. Preliminary analysis of arrhythmias after the Fontan operation with extracardiac conduit compared with intra-atrial lateral tunnel. Thorac Cardiovasc Surg 2001;49: Shirai LK, Rosenthal DN, Reitz BA, Robbins RC, Dubin AM. Arrhythmias and thromboembolic complications after the extracardiac Fontan operation. J Thorac Cardiovasc Surg 1998;115: DISCUSSION DR ERLE H. AUSTIN III (Louisville, KY): I enjoyed that. I think it is an important study. As you pointed out, most centers prefer one technique or another, and this is rare, maybe not presented before, to compare both techniques over the same time period at a single center by a single surgeon. I have three questions. First of all, it wasn t clear to me how you decided which technique you were going to use. You referred to the fact that the decision was based on anatomic reasons. What were those anatomic decisions, because I noticed that you used both techniques in hypoplasts, for instance? What made you decide in one hypoplast to use the extracardiac conduit and in another one to use the lateral tunnel? My second question is how exactly did you perform the fenestration in the extracardiac Fontans? And then my third question is what is your preference now? DR KUMAR: To answer the first question, in general, patients with hypoplastic left heart syndrome underwent a hemi-fontan procedure, followed by a lateral tunnel Fontan procedure. The decision to do the hemi-fontan was partially based on the consideration that many of these patients had left pulmonary artery hypoplasia, which is well dealt with by a hemi-fontan. In patients with other anatomic diagnoses, if augmentation of the central or left pulmonary artery was needed, a hemi-fontan was also utilized. Regarding the lateral tunnel fenestration, it was done by a punch fenestration of 4 mm in the prosthetic baffle, which is made of a PTFE patch. The current preference, I leave the question for the surgeon who is here. DR SCOTT M. BRADLEY (Charleston, SC): We make the choice of staging operations at the time of the second stage. We have been impressed with the results obtained by several other groups in patients with hypoplastic left heart syndrome using the combination of a hemi-fontan followed by an intraatrial lateral tunnel. Some of the advantages may be the routine augmentation of the central and left pulmonary arteries, as well as the subsequent avoidance of redissecting the pulmonary arteries near and behind the reconstructed neoaorta at the time of the lateral tunnel. On the other hand, the bidirectional Glenn-extracardiac conduit combination offers clear advantages in patients with anomalies of systemic and pulmonary venous drainage. However, these are guidelines, and as Dr Kumar mentioned, the approach was individualized. For example, a hypoplast with an adequate left pulmonary artery who needed an intracardiac procedure at the time of the second procedure (such as atrioventricular [AV] valve repair) may have undergone a bidirectional Glenn (limiting the time of cardiac arrest to the AV valve repair), followed by an extracardiac conduit. We do avoid a bidirectional Glenn followed by a lateral tunnel because of the particularly high incidence of sinus node dysfunction seen with this combination. It had been my hope that we would have clearer rhythm data clearly favoring one approach or the other, and that may become available with longer follow-up. DR W. STEVES RING (Dallas, TX): It is intriguing to me that you have a major difference in sinus node dysfunction in an operation where you never go near the sinus node at the second operation, and I was wondering if you could enlighten us a little bit. It seems like it might be more related to the second stage, the hemi-fontan versus the complete transection of the superior vena cava and dissection around the sinus node. Can you give us an indication of what the level of sinus node dysfunction was prior to the Fontan or following the second stage operation in these two groups? DR KUMAR: In this study we did not specifically look at rhythm status following the superior cavopulmonary connection. However, in a previous study, we found that there was no difference in the incidence of sinus node dysfunction following a hemi- Fontan and a bidirectional Glenn. This has also been reported by Cohen and colleagues from Children s Hospital of Philadelphia (see reference [18], mentioned in this study, for more details). DR BRADLEY: May I just add that all of the rhythm information that Dr Kumar presented was in patients who were in sinus rhythm at the time of the Fontan operation. There were 3 or 4 patients in the series who were not in sinus rhythm at the time of the Fontan operation, and were not included in the rhythm information that was presented. DR RING: Do you have any explanation for it? Since you really do no dissection around the sinus node or on the upper atrium usually in the extracardiac conduit Fontan, do you have any explanation for the extent of sinus node dysfunction in those patients? DR KUMAR: One possible explanation is that following a bidirectional Glenn the superior aspect of the right atrium generally is adherent to the right pulmonary artery. In redissecting the right pulmonary artery at the time of the extracardiac conduit, the sinus node and its blood supply may be at risk. Some patients having an extracardiac conduit will also have an atrial incision, either for associated procedures, or fenestration placement. This is another potential source of damage to the sinus node or its blood supply, especially as the landmark of the

9 Ann Thorac Surg KUMAR ET AL 2003;76: LATERAL TUNNEL VS EXTRACARDIAC CONDUIT FONTAN superior cavoatrial junction is no longer present. A similar incidence of early sinus node dysfunction after extracardiac conduit has also been seen by other groups who have looked at this issue. DR AUSTIN: The patients who had the lateral tunnel, who did develop sinus node dysfunction later, were they hemi-fontans or were they bidirectional Glenns? DR KUMAR: The hemi-fontan patients had five cases in the midterm follow-up that developed sinus node dysfunction in mid-term follow-up, which was not present earlier. DR BRADLEY: I think he was asking, among the lateral tunnel patients who have sinus node dysfunction late, how many of them had hemi-fontans as their staging? DR KUMAR: All of them did DR AUSTIN: How many of the extracardiac conduits that developed sinus node dysfunction had had hemi-fontans before? DR KUMAR: All of our extracardiac conduit Fontans had a bidirectional Glenn as a first stage.