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The study aim was to compare Fontan patients undergoing lateral tunnel (LT) versus extracardiac conduit (ECC) technique.
Fontan patients (LT vs ECC) from January 2000 to December 2017 were analyzed retrospectively. Baseline characteristics were analyzed as covariates. Primary outcomes (ie, mortality, Fontan failure, thrombosis, and pacemaker implantation) were compared using time-to-event models. Subgroup analysis including only initially fenestrated cases and propensity score matching were performed.
Eight hundred one Fontan patients: LT (n = 638) versus ECC (n = 163) were included. Median follow-up time was 4.8 years (range, 1.1-10.8 years). Baseline characteristics were similar except for age: LT versus ECC: 2.6 years (range, 2.2-3.2 years) versus 3.1 years (range, 2.6-4.7 years) (P < .01) and mean pulmonary artery pressure: LT versus ECC: 12 mm Hg (11-15 mm Hg) versus 11 mm Hg (10-13 mm Hg) (P < .05). Early mortality was significantly higher in ECC versus LT group (3.1%; vs 0.5%; P < .05). Freedom from death, heart transplantation and Fontan failure were significantly longer in LT vs ECC (P < .01). After correcting for age, diagnosis, surgical technique, surgeon, mean pulmonary artery pressure, and fenestration, the ECC group showed worse freedom from death (hazard ratio, 2.8; P < .01) and Fontan failure (hazard ratio, 3.0; P < .01). No difference in pacemaker implantation rate was demonstrated (P = .25). Early fenestration closure was associated with higher risk of early (hazard ratio, 30.5) and late mortality (hazard ratio, 3.5). After matching, log-rank tests showed significant differences between the 2 groups for Fontan failure at 5 and 10 years (P < .01) and mortality at 5 years (P = .02).
When compared with ECC, LT Fontan is associated with better short and midterm outcomes. Spontaneous fenestration closure is an independent risk factor for early/late mortality.
The total cavopulmonary connection (Fontan procedure) has undergone many modifications in order to improve early and long-term outcomes and to reduce complications of the Fontan circulation. The two most commonly utilized techniques are the intra-atrial baffle/lateral tunnel (LT), first described in 1988
Despite the improvement in early and late outcomes after Fontan procedure, complications associated with the Fontan circulation such as arrhythmia, thromboembolism, plastic bronchitis, or protein-loss enteropathy present significant challenges and ultimately lead to Fontan failure, transplantation, or death.
The aim of this study was to compare early and midterm outcomes of patients with single ventricle morphology, either undergoing LT or ECC in a single center experience.
All patients undergoing either lateral tunnel (LT group) or extracardiac conduit (ECC group) Fontan procedure from January 2000 to December 2017 at Boston Children's Hospital (BCH) were included in this analysis and retrospectively reviewed. Patients who underwent other techniques of Fontan such as right atrial to pulmonary artery, or right atrial to right ventricle conduits were excluded from the analysis. The research protocol (IRB-P00028320) was approved by the Institutional Review Board of BCH.
The primary method of superior cavopulmonary connection (stage 2) at our institution is bidirectional Glenn. A minority of patients transferred to BCH from other institutions had undergone hemi-Fontan.
LT Fontan technique was performed as previously developed by Jonas and Castaneda.
After median sternotomy, aortic cannulation, and bicaval cannulation, hypothermic cardiopulmonary bypass was established and either aortic crossclamping and cardioplegic arrest or induced ventricular fibrillation were performed. First, the right atrium was opened parallel to the atrioventricular groove, and the incision was extended onto the right atrial appendage. The superior-most edge of the atrial appendage was anastomosed directly to the confluence of the superior vena cava/right pulmonary artery creating the posterior wall of the baffle. A polytetrafluoroethylene patch or tube graft (10 mm, thin-walled), opened longitudinally, was inserted to direct the blood flow from the inferior vena cava to the orifice of the superior vena cava and the right pulmonary artery. Fenestration was then created in the polytetrafluoroethylene baffle directed toward the dominant ventricle with a coronary punch and the right atrium was closed and de-aired (Video 1).
ECC Fontan procedure was performed in a standard fashion described in literature.
ECC technique has been performed on cardiopulmonary bypass with or without aortic crossclamping.
All patients who underwent Fontan procedure were followed from the time of their Fontan procedure to the last available clinical visit. Preoperative baseline characteristics such as age at the time of Fontan, gender, diagnosis, ventricular dominance (right dominant vs left dominant), preoperative mean pulmonary artery pressure (mPAP) (in millimeters mercury), pulmonary vascular resistance (PVR) (in Woods units [WU]) and follow-up time (in years) were collected.
Intraoperative prognostic markers such as cardiopulmonary bypass time, crossclamp time, and additional cardiac procedure at the time of Fontan were noted as well.
Postoperatively, time to extubation (in days), time until last chest tube was removed (in days), intensive care unit (ICU) stay (in days) and total hospital stay (in days) were collected.
Mortality (in-hospital early mortality, long-term mortality), incidence of Fontan failure, incidence of pacemaker implantation and baffle/conduit thrombosis were recorded as primary complications.
Postoperative arrhythmias (eg, tachyarrhythmia or bradyarrhythmia), bleeding, protein-losing enteropathy, neurological disorders (eg, stroke or seizures), pleural effusions, ascites, total body edema, development of collaterals, liver complications (eg, cirrhosis or portal hypertension), lung complications (eg, plastic bronchitis), chylothorax, pulmonary artery stenosis and phrenic nerve palsy were categorized as secondary complications. Freedom from death, Fontan failure, or heart transplantation (HTX) were analyzed individually.
Fontan failure was defined as either an early event (within hours postoperatively) or a late-onset failure of the Fontan circulation with symptoms of desaturation, elevated Fontan pressures, elevated central venous pressure, low cardiac output, protein-loss enteropathy, arrhythmia, or plastic bronchitis leading to a Fontan takedown, a Fontan conversion, HTX, or ventricular assist device implantation.
Fontan patients with an initial fenestration were compared with ones who did not have a fenestration at the time of Fontan and the influence of initial fenestration placement was analyzed in terms of early/late mortality, Fontan failure, HTX, risk for prolonged pleural effusion time (>10 days) and prolonged ventilation time (>7 days). Prolonged effusion time was noted clinically by prolonged effusion/drainage from pleural drains, which led to delayed removal.
Among the subset of patients with initial fenestration placement, the influence of early fenestration closure on mortality and morbidity was analyzed. Early fenestration closure was defined as fenestration closure before hospital discharge and was noted either echocardiographically during the last checkup before discharge or by catheterization due to hemodynamic instability during the hospital stay.
The influence of initial diagnosis and ventricular morphology (single right vs left ventricle) on the outcome of Fontan procedures was analyzed as well.
Additionally, most recent exercise stress test data (eg, peak work rate, peak oxygen consumption, peak oxygen pulse, forced vital capacity, forced expiratory volume in 1 second, peak heart rate, minute ventilation/carbon dioxide production slope, oxygen saturation, and body mass index) were analyzed to compare the 2 groups in terms of long-term performance.
Baseline characteristics in both groups were presented as median (interquartile range [IQR]) when continuous data and as number (%) of patients when categorical data and compared using nonparametric Mann-Whitney U test. Proportions were compared by Fisher exact test.
Primary complications and time-to-event outcomes were analyzed using the Kaplan-Meier method. Possible confounders such as age, gender, diagnosis, ventricular dominance, mPAP, PVR, initial fenestration, surgeon, and year of surgery were treated as covariates and adjusted for using Cox proportional hazards regression. Additionally, 3:1 (LT:ECC) propensity score matching was performed using the method of the nearest neighbor without replacement with respect to following baseline covariates between the groups: age, fenestration, heterotaxy, ventricular dominance, and concomitant procedures.
The absolute standardized mean difference (d statistic) was computed in the prematched groups and postmatching data to assess the success of the matching procedure in reducing differences in baseline characteristics between the groups. Kaplan-Meier curve analysis with the log-rank test was performed using the matched data to compare time-to-event outcomes between the groups. Statistical analysis was performed using IBM-SPSS version 24.0 (IBM-SPSS Inc, Armonk, NY). Propensity score matching was done in R (R Foundation for Statistical Computing, Vienna, Austria).
A total of 801 patients underwent Fontan procedure utilizing either LT (n = 638; 80%) or ECC (n = 183; 20%) technique at BCH from January 2000 to December 2017 and were included in this retrospective study. Distribution of Fontan type changed varied the study period, with only 9% of patients undergoing Fontan by ECC technique in the year 2000 and more than half (54%) of all patients undergoing the ECC technique in 2017.
For the entire cohort, the median age at time of Fontan was 2.7 years (IQR, 0.6-34.7 years), median weight was 12.4 kg (IQR, 7.2-70.9 kg) and the male gender was more dominant among all Fontan patients (61%). Patients in the LT group were younger at time of surgery compared with the ECC group: 2.6 years (IQR, 1.6-3.6 years) versus 3.1 years (IQR, 1-5.1 years) (P =0 .01) and median weights were lower in the LT versus ECC group: 12.2 kg (IQR, 10.7-15.8 kg) versus 14.2 kg (12.1-19.9 kg) (P < .01), whereas gender distribution was not significantly different between the groups (P =0= .14). In the LT group, right dominant ventricular morphology (60%) was more common, whereas in the ECC group right (50%) and left dominance (50%) were more or less equally distributed (P = .02). More than half (54%) of all patients in the LT group were diagnosed with hypoplastic left heart syndrome compared with 37% in the ECC group (P <0= .01) (Table 1).
Table 1Baseline characteristics of all Fontan patients, lateral tunnel (LT) group versus extracardiac conduit (ECC) group
Statistically significant difference (P < .05) between LT and ECC group.
Values for continuous data are presented as median (interquartile range), values for categorical data are presented as n (%) of patients. LT, Lateral tunnel; ECC, extracardiac conduit; LD, left dominant; RD, right dominant; HLHS, hypoplastic left heart syndrome; DILV, double inlet right ventricle; AV, atrioventricular; TGA, transposition of the great arteries; PAP, pulmonary artery pressure; PVR, pulmonary vascular resistance; WU, Woods units.
∗ Statistically significant difference (P < .05) between LT and ECC group.
Median preoperative mPAP and PVR were higher in the LT group compared with the ECC group: 12 mm Hg (IQR, 11-15 mm Hg) versus 11 mm Hg (IQR, 10-13 mm Hg) (P < .05) and 2 WU (IQR, 1-2 WU) versus 1 WU (IQR, 1-2 WU) (P = .07).
Intraoperative Prognostic Factors
A fenestration during Fontan procedure was performed significantly more frequently in the LT group compared with ECC group (99% vs 77%) (P < .001).
Concomitant procedures at the time of Fontan procedure were more frequent in the LT group compared with the ECC group (40% vs 31%) (P < .05). The most common additional procedures during Fontan surgery in the LT group were pulmonary artery plasty (15%) and tricuspid valve repair (TVR) (11%), which were performed simultaneously in 9.2% and 3.7% in all ECC cases (P = .5 and P < .01). Aortic valve repair and atrioseptectomy were more frequently done during ECC versus LT procedure 2.5% versus 1.3% and 6.7% versus 4.9%, although not significantly (P = .3) (See Table 2 for more details).
Table 2Intraoperative and early postoperative prognostic factors, lateral tunnel (LT) group versus extracardiac conduit (ECC) group
Statistically significant difference (P < .05) between LT and ECC groups.
Values for continuous data are presented as median (interquartile range) or mean ± standard error of the mean, and values for categorical data are presented as n (%) of patients. LT, Lateral tunnel; ECC, extracardiac conduit; AV, atrioventricular; CPB, cardiopulmonary bypass time, CC, crossclamp time; ICU, intensive care unit.
∗ Statistically significant difference (P < .05) between LT and ECC groups.
LT Fontan technique was performed on cardiopulmonary bypass with either aortic crossclamping or induced ventricular fibrillation in all patients, whereas ECC Fontan technique was performed on cardiopulmonary bypass with aortic crossclamping in 38.4% of cases (53 patients). Mean cardiopulmonary bypass time was longer in LT compared with ECC (118 ± 37 minutes vs 100 ± 37 minutes; P = .01), and mean aortic crossclamp time was longer in the LT group compared with the ECC group (66 ± 31 minutes vs 20 ± 32 minutes; P < .001) (See Table 2).
Early Morbidity and Mortality
During the immediate postoperative period, no differences were noticed between the groups in terms of time to extubation (in days), time until last chest tube was removed (in days), ICU stay, and total hospital stay (in days) (see Table 2).
In-hospital mortality however was higher in the ECC group compared with the LT group: 3.1% versus 0.5% (P < .01). We found thromboembolic events (eg, tunnel thrombosis and embolic cerebral infarction) in 80% of the early deaths in the ECC group and Fontan failure in 67% as the suggested cause of death in the LT group. Complications in the patients who died patients are demonstrated in Table E1. In 60% of all hospital deaths, the fenestration closed spontaneously and cardiopulmonary bypass time was 228 ± 46 minutes in this group.
Aspirin was used postoperatively in the majority of all Fontan patients (n = 717; 89.5%). Warfarin was given to a small number of patients who had embolic events (eg, stroke) described before the Fontan procedure (n = 84; 10.4%). Warfarin was mainly used in the ECC group (54 out of 163; 33.1%) versus LT group (30 out of 638; 4.7%). Among the patients who died we found 77.7% (7 out of 9) were taking warfarin in the ECC group versus 4.5% (1 out of 22) in the LT group.
Kaplan-Meier time-to-event curves representing freedom from mortality among all Fontan patients demonstrates that the estimated freedom from mortality for the entire observation period was significantly better for patients in the LT group compared with the ECC group (P = .03 by log-rank test) with overall survival rates at 5, 10, and 20 years of 96.4%, 94.5%, and 93.9%, respectively, in the LT group versus 92.0%, 91.4%, and 90.8%, respectively, in the ECC group.
Because the number of patients at risk decreases quite a bit after 10 years of follow-up, survival plots showing 5-year (Figure 1) and 10-year freedom from mortality among all Fontan patients were created and showed similar results.
Correcting for possible confounders such as age, ventricular morphology, fenestration at the time of Fontan procedure, preoperative mPAP and surgeon's experience, the surgical technique was an independent risk factor for mortality with a hazard ratio (HR) of 2.7 (P < .05) for the ECC technique.
Kaplan-Meier survival plot representing the freedom from Fontan failure among all Fontan patients demonstrated that the estimated freedom from Fontan failure was significantly better in the LT group versus ECC group (P = .02, log-rank test) (Figure 2).
Kaplan-Meier analysis demonstrates that estimated freedom from pacemaker implantation (P = .41) and freedom from thrombosis (P = .22) were not different between the groups.
Cox regression adjusting for possible confounders that could influence the need for pacemaker implantation, including simultaneous surgeries during initial Fontan procedure, age, and ventricular morphology, showed that the surgical technique was not independently associated with pacemaker implantation; however, the performance of a tricuspid valve repair was an independent risk factor with (HR, 2.1; P < .01). The odds ratio (OR) for development of an atrioventricular block or a sinus node dysfunction when underdoing simultaneous TVR at the time of Fontan, was 9.1 (95% confidence interval [CI], 4-23.6) and 2.6 (95% CI, 1.2-6-1).
All secondary complications/outcome measurements (eg, tachyarrhythmia, atrioventricular block, sinus node dysfunction, ascites, total body edema, bleeding, neurological dysfunction, pulmonary artery stenosis, collaterals, chylothorax, liver complications, cholecystitis, plastic bronchitis, protein-loss enteropathy, and phrenic nerve palsy) were not significantly different (all P values > .10) between the groups except for pleural effusions, which occurred significantly more often in the ECC group (8.6% vs 3.9%; P = .01) (Table 3).
Table 3Secondary complications/outcomes of Fontan patients, lateral tunnel (LT) group versus extracardiac conduit (ECC) group
The percentage of all Fontan patients who experienced Fontan failure in the LT group compared with the ECC group was 2.7% versus 4.9% (P < .1). HTX rates were very similar between the groups (1.8% vs 2.3; P = .6). Kaplan-Meier time-to-event curve illustrating Fontan failure and transplant-free survival among all Fontan patients shows estimated freedom from death, Fontan failure, and HTX was significantly better in the LT group compared with the ECC group (P = .03, log-rank test).
The Influence of Fenestration on the Outcome of Fontan Patients
Compared with patients who underwent initial fenestration at Fontan, those who did not undergo fenestration placement at time of Fontan procedure had a significantly higher incidence of prolonged (<10 days) chest effusion time (25% vs 12.7%; P = .04) but lower in-hospital and total mortality rates and lower Fontan failure rates (Table 4).
Table 4Complications comparing Fontan patients with initially nonfenestrated versus fenestrated Fontan procedure
Patients with initial fenestration had a longer cardiopulmonary bypass time compared with patients with nonfenestrated Fontan (115 minutes vs 98 minutes; P < .05).
However, among patients who underwent initial fenestration at time of Fontan, those who experienced a spontaneous fenestration closure before discharge had significantly higher OR for hospital mortality (OR, 30.5; 95% CI, 4.9-188.2), total mortality (OR, 3.2; 95% CI, 1.2-8.8), Fontan failure (OR, 4.4; 95% CI, 1.2-15.8), and complications such as extracorporeal membrane oxygenation use (OR, 8.5; 95% CI, 3-23.5).
The proportion of spontaneous early fenestration closure was significantly higher in the ECC group compared with the LT group (14% vs 4%; P < .01).
Analyzing only initially fenestrated Fontan cases and adjusting for all possible confounders, including early fenestration closure in a multivariate Cox-regression model, we still found surgical technique to be the only independent risk factor for mortality (HR, 3.8; 95% CI, 1.2-11.7; P = .02) for the ECC group.
The Influence of Ventricular Morphology on the Outcomes of Fontan Patients
Incidences of sinus node dysfunction and pacemaker implantation were higher in the right dominant morphology group compared with the left dominant group (5.6% vs 2.4% [P = .03] and 8.6% vs 4.5% [P = .02]).
Right ventricular morphology demonstrated an independent risk factor for total mortality (HR, 2.4; P = .05) and Fontan failure (HR, 2.5; P = .05).
Most Recent Exercise Performance Rate
In the last available exercise stress tests, LT group versus ECC group did equally in almost all parameters except for peak work rate and peak oxygen pulse, which was significantly better in the LT group (Table 5).
Table 5Exercise stress test (most recent): Lateral tunnel (LT) group versus extracardiac conduit (ECC) group
Peak work rate was higher in the left dominant morphology patients compared with patients with right dominant ventricles 105.5 W (95% CI, 75.5-135.5) versus 95 W (95% CI, 65-125).
The median time from the date of the Fontan procedure to the date of the last available exercise/stress test was 10.8 years (IQR, 8.4-14.3 years) within the entire cohort; 11.0 years (IQR, 8.7-14.5 years) in the LT group and 8.4 years (IQR, 7.2-8.9 years) in the ECC group (P = .02).
Because the minimal age for exercise stress testing at BCH is older than age 6 years, and quite a few patients were lost in follow-up, not all Fontan patients had available stress tests to compare. However, among the patients without available exercise tests mean follow-up time was 4.66 ± 4.8 years and survival rate was 91.7%.
Propensity Score Matching
After 3:1 propensity score matching, our 2 groups contained 489 patients (LT group) and 163 patients (ECC group). Long-rank tests showed significant differences between the 2 groups for Fontan failure in the entire follow-up time (P = .03) (Figure E1), Fontan failure at 5 (Figure E2), and 10 years (Figure E3) of follow-up (P < .01) and mortality at 5 years of follow-up (P = .02) (See Figure 3). Mortality at 10 years of follow-up and rate of pacemaker implantations at 5 and 10 years of follow-up were not significantly different between the groups.
Several techniques have been developed for total cavopulmonary connection, with ECC technique gaining popularity in the recent years as the preferred method of reconstruction.
associated with the ECC technique have prompted this shift in practice. Preservation of ventricular and pulmonary function is provided by normal atrial pressures, the avoidance or minimal use of cardiopulmonary bypass and cardioplegic cardiac arrest as well as the lack of atrial distention in this group. However, also disadvantages of the ECC technique are described such as the lack of growing potential of the ECC resulting in the need of reoperations.
Experience with LT Fontan technique on the other side has been extensive and the ability of completing the Fontan circulation at a younger age caused by the growth potential of the cavopulmonary pathway, which theoretically avoids the need of reoperation.
In this retrospective single-center study, patients undergoing LT Fontan demonstrated significantly lower early and midterm mortality rates, longer freedom from Fontan failure, but longer operating room times (ie, aortic crossclamp and cardiopulmonary bypass times) compared with those undergoing ECC. Freedom from other complications such as pacemaker implantation and thromboembolism were not significantly different between the 2 cohorts. ECC technique demonstrated a higher early fenestration closure rate. These major findings are summarized in Figure 4, indicating that the LT Fontan technique should be reconsidered as a third-stage palliation for patients with univentricular morphology.
Differences in preoperative patient characteristics were significant and influenced the results. Both LT and ECC cohorts were similar except for age at surgery, weight at surgery, ventricular dominance, and preoperative mPAP, yet attempts to correct for these confounders using a Cox-regression analysis did not significantly alter the conclusions.
An additional performed propensity matching analysis matching for differences in baseline characteristics between both groups such as age, fenestration, heterotaxy, ventricular dominance, and concomitant procedures showed similar results except for mortality rates above 5 years that did not show significant differences between the 2 groups anymore. Previous studies have suggested that older age at time of Fontan procedure (>3 years),
are associated with better outcomes after Fontan procedure. Compared with the ECC group, the LT group in our study was younger in age, had a higher proportion of right ventricular morphology, and had higher preoperative mPAP; despite the less-favorable preoperative characteristics, the LT group demonstrated significantly better early mortality and long-term outcomes (ie, freedom from death, Fontan failure, and cardiac transplantation).
Cardiopulmonary bypass and aortic crossclamp durations were significantly longer in the LT group compared with ECC group. Although this finding can be partially attributed to higher frequency of concomitant procedures during LT compared with ECC (40% vs 30.7%), the difference in operative times persisted even in patients not undergoing concomitant procedures. The complexity of the LT technique compared with the ECC technique and need for intracardiac tunneling contribute to differences in operative times between the cohorts. Although longer operative times are believed to contribute to prolonged ICU and hospital lengths of stay,
the LT group in our study did not differ significantly from the ECC group in duration of mechanical ventilation, ICU stay, or total hospital stay.
The most significant finding of this study was the difference in early and late midterm mortality and Fontan failure rates between the cohorts, with LT being associated with survival advantage and lower rates of Fontan failure compared with ECC. When looking at the Kaplan-Meier curves for survival and Fontan failure the ECC group curve shows an early drop and then becomes flatter, suggesting that the majority of deaths/Fontan failures occur early after Fontan procedure. These early deaths in the ECC group were mainly attributed to thromboembolic events, and suggests a possible benefit of anticoagulation after ECC technique.
Spontaneous fenestration closure before discharge, which occurred in 60% of early mortalities was an independent risk factor for mortality and occurred more frequently in ECC patients. Antithrombosis therapy for most patients consisted of aspirin monotherapy, whereas several centers have advocated for warfarin anticoagulation after Fontan.
Although controversy exists regarding necessity of fenestration at the time of Fontan, several studies have demonstrated potential benefit in terms of early postoperative chest tube drainage and shorter hospital length of stay.
In addition to being a risk factor for early mortality (HR, 42.8), spontaneous fenestration closure before discharge in our series was an independent risk factor for late Fontan failure (HR, 5.7) and late mortality (HR, 5.8). Retrospectively, it is very difficult to say whether the patients who experienced early fenestration closures had an inferior outcome because of the closed fenestrations or whether these patients had inferior hemodynamics before Fontan procedure and therefore the fenestrations closed early and spontaneously. When looking at the mPAP and PVR before Fontan, the ECC patients, in which the fenestrations closed significantly more frequently than in the LT group, actually had more favorable hemodynamic parameters (lower mPAP and PVR) compared with LT patients. Therefore, it is very difficult to draw conclusions and it will need more, and ideally prospective, studies to answer this question satisfactorily.
Regarding overall midterm morbidity and mortality after Fontan procedure, most studies in literature describe no significant differences in outcomes between LT and ECC techniques.
which suggested worse long-term mortality associated with LT compared with ECC. The reasons for the discrepancy between the results of that and our study are unclear, but differences in study design, age at surgery, and duration of follow-up may be important considerations.
Incidence of arrhythmia and pacemaker implantation in this study was not significantly different between patients undergoing LT and ECC. However, other investigators have demonstrated a higher proportion of sinus node dysfunction and pacemaker implantations in LT compared with ECC patients.
Important confounders in our analysis were rate of concomitant TVR, which was an independent risk factor for pacemaker implantations (HR, 2.1), and right-dominant versus left-dominant ventricular morphology. Yet despite the higher proportion of concomitant TVR and right-dominant ventricular morphology in LT compared with ECC patients, the rates of sinus node dysfunction and pacemaker implantation were not significantly different between the groups.
Compared with Fontan patients with left-dominant ventricular morphology, patients with right-dominant ventricles showed higher pacemaker implantation rates and a worse outcome in terms of total mortality. Similar results have been reported in the literature.
The worse outcome of the right-dominant group can also be related to the fact that the majority of these patients had a diagnosis of hypoplastic left heart syndrome, which is known as a risk factor for unfavorable outcomes after single-ventricle palliation.
In terms of exercise/stress testing, the LT group showed a higher peak work rate (in watts) and a higher peak oxygen pulse compared with the ECC group, suggesting a better decrease in systemic ventricular volume overload in Fontan patients being operated using the LT technique. This difference was statistically significant, but the influence on quality of life and functional measures was not assessed. The median time from the date when Fontan procedure was performed to the date of the last-available stress/exercise test was significantly different between the 2 groups: In the LT group, median time from Fontan-exercise test was 11 years (IQR, 8.7-14-5 years) and in the ECC group was 8.4 years (IQR, 7.2-8.9 years) (P = .02). This difference was probably caused by the fact that surgeons started performing ECC Fontan procedure later than LT technique and also a fair amount of patients were lost in follow-up in this group (27%). However, literature describes a slow decline of oxygen consumption with a longer time from Fontan procedure,
which suggests that patients in the LT group actually had a disadvantage because they have been living with their Fontan circulation for a longer time. However LT patients in this study actually performed equally to superior.
Also, patients with LD ventricular morphology showed a better exercise performance than patients with right-dominant ventricles, which is consistent with previous reports in the literature.
Important confounding factors in this analysis include era affect and learning curve. The ECC technique was more common in the most recent years of the study, whereas LT technique has been performed for a much longer period of time at our institution.
With the emergence of excellent outcomes with ECC, surgeons have begun to perform this procedure more frequently, so that the proportion of ECC Fontan procedures at BCH has increased over the past 10 years with more than half of all patients undergoing the ECC technique during that time. Another limitation of this study is the generally quite short follow-up time (median, 4.8 years) in the entire cohort and the differences in follow-up time between the groups, which is why it was decided to show Kaplan-Meier time-to-event curves up to 5 years of follow-up to provide a more fair comparison between the groups.
When compared with ECC, LT Fontan is associated with better short-term and midterm mortality and morbidity with no increased risk of pacemaker implantations. Spontaneous FC is an independent risk factor for early and late mortality. Left ventricular morphology is associated with lower frequency of pacemaker use and a superior long-term mortality compared with patients with single right ventricles.
LT Fontan procedure at Boston Children's Hospital. This video shows a case of a patient with HLHS, S/p Glenn procedure who underwent LT tunnel Fontan procedure with a 4-mm fenestration and atrial septectomy at BCH in 2019. Video available at: https://www.jtcvs.org/article/S0022-5223(19)33962-5/fulltext.
de Leval M.R.
Total cavopulmonary connection: a logical alternative to atriopulmonary connection for complex Fontan operations. Experimental studies and early clinical experience.
We enjoyed the recent article by Weixler and colleagues,1 which shows an improvement in the survival of patients who underwent a Fontan operation with a lateral tunnel compared with an extracardiac conduit (EC). This study compared 638 patients who underwent the Fontan with the lateral tunnel with 163 patients who received the EC technique. The authors demonstrated that a lateral tunnel Fontan is associated with better short-term and midterm outcomes and that early spontaneous fenestration closure is an independent risk factor for mortality.
Okay, I will admit that I do not like to change. It is difficult to see that what you have done for years may not be the right way and then head in a different direction, whether with respect to medical treatment of a particular nature, in a relationship, or in practicing surgery for congenital heart disease. I think this is particularly true for surgical techniques, where there are very few randomized studies proving that one technique is better than another (actually, that's also true for relationships).