Eur J Cardiothorac Surg 2008;34:726-731. doi:10.1016/j.ejcts.2008.06.040
Copyright © 2008, European Association for Cardio-thoracic Surgery. Published by Elsevier. All rights reserved.
Outcomes following non-valved autologous reconstruction of the right ventricular outflow tract in neonates and infants
Christopher D. Derby*,
Jacek Kolcz,
Samuel Gidding,
Christian Pizarro
Nemours Cardiac Center, Alfred I. duPont Hospital for Children, Wilmington, DE 19803, United States
Received 18 January 2008;
received in revised form 16 June 2008;
accepted 23 June 2008.
* Corresponding author. Address: Nemours Cardiac Center, Alfred I. duPont Hospital for Children, P.O. Box 269, Wilmington, DE 19899, United States. Tel.: +1 302 651 6600; fax: +1 302 651 5345. (Email: cderby{at}nemours.org).
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Abstract
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Objective: Controversy surrounds the optimal method of establishing right ventricle to pulmonary artery continuity in neonates and infants with congenital heart disease. We reviewed our experience with non-valved autologous reconstruction of the right ventricular outflow tract to determine mid-term outcome and risk factors for reintervention. Methods: Between 1998 and 2006, 34 consecutive patients underwent non-valved autologous right ventricular outflow tract reconstruction. The need for postoperative catheter-based intervention or reoperation was assessed using relevant patient and procedure-related variables. Results: Diagnoses included tetralogy of Fallot with anomalous coronary (n
= 3), tetralogy of Fallot with pulmonary atresia (n
= 10), truncus arteriosus communis (n
= 15), and other (n
= 6). Median age at surgery was 5 days (1–270 days). Twenty-six (76%) patients were neonates. Median weight was 3.1 kg (1.8–7.3 kg). At a median follow-up of 43 months (1–90 months), 15 (50%) patients underwent reoperation and 7 (23%) underwent catheter-based intervention, with a total of 16 (53%) undergoing either reoperation or catheter-based intervention. Kaplan–Meier freedom from reintervention at 6 months, 1 year, 3 years, and 5 years was 67%, 47%, 47%, and 35% for truncus arteriosus versus 87%, 82%, 68%, and 65% for diagnoses other than truncus arteriosus (p
= 0.05). Conclusions: Mid-term outcome following non-valved autologous reconstruction of the right ventricular outflow tract is satisfactory and constitutes a sound alternative to the use of small-diameter conduits in neonates and infants. In our hands, this strategy favors certain anatomic subtypes. Non-truncus patients have significantly lower rates of reintervention. Technical details associated with the anatomical reconstruction of the posterior autologous pathway may play an important role in outcomes.
Key Words: Congenital heart surgery • Neonatal • Right ventricular outflow tract reconstruction
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1. Introduction
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The strategy of primary repair for neonates and young infants with congenital heart malformations is well documented and has the advantage of restoring a normal circulation with favorable effects on early development and long-term cardiac function [1–3].
The availability of extracardiac conduits has enabled successful repair in patients who require restoration of right ventricle (RV) to pulmonary artery (PA) continuity. However, because of lack of somatic growth and early degeneration, particularly in neonates and young infants, the use of extracardiac conduits is associated with inevitable reintervention. Restoration of RV to PA continuity using autologous tissue has the potential for growth and, therefore, might reduce the number of reinterventions.
This study analyzes the outcome of 34 consecutive patients who underwent non-valved autologous reconstruction of their right ventricular outflow tract (RVOT). We sought to determine durability and risk factors for reintervention.
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2. Patients and methods
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2.1 Patients
We reviewed the records of all patients undergoing primary repair of congenital heart malformations requiring RVOT reconstruction from January 1998 through December 2006 at Nemours Cardiac Center, Alfred I. duPont Hospital for Children. During this time interval, our universal approach to repair in these patients was a non-valved autologous reconstruction. Exclusion criteria included patients with discontinuous pulmonary arteries (hemitruncus and pulmonary atresia with major aortopulmonary collateral arteries) and patients with tetralogy of Fallot (TOF) that underwent a standard transannular repair. Patient and procedural variables that were evaluated included age, weight, diagnosis, associated cardiac and extra-cardiac anomalies, preoperative morbidity, mortality, and need for catheter-based intervention (CBI) or reoperation among survivors. This study was approved by the local institutional review board, and the need for consent was waived.
2.2 Operative procedure
The underlying cardiac anomalies are identified in Table 1
. Repair was accomplished with hypothermic cardiopulmonary bypass utilizing brief periods of circulatory arrest. Cold crystalloid cardioplegia was used for myocardial protection. The ventricles were partitioned through a right ventriculotomy using a Dacron patch for ventricular septal defect (VSD) closure and creation of a left ventricular outflow tract baffle to the aorta when necessary.
All patients underwent non-valved autologous RVOT reconstruction. The posterior floor of the outflow tract consisted of the patient's native tissue that was augmented anteriorly with a patch of pulmonary allograft. The patch was extended onto the branch pulmonary arteries if deemed necessary. When there was considerable distance between the RV and PA or in the presence of an anomalous coronary artery, continuity was restored using a PA or truncal tissue flap, interposition of left atrial appendage, or direct PA translocation, as previously described [4–7]. The three patients with TOF and anomalous coronary artery crossing the RVOT underwent reconstruction with a PA flap used to bridge the anomalous coronary. Two patients with transposition of the great arteries (TGA)/VSD/pulmonary stenosis (PS) underwent a modified Rastelli reconstruction where a PA flap was rotated over the aorta and approximated to the ventriculotomy. A third patient with TGA/VSD/PS and anomalous coronary crossing the RVOT had interposition of the left atrial appendage between the ventriculotomy and main PA. Of the 15 patients with truncus arteriosus communis (TAC), 12 had a truncal tissue flap and 3 underwent direct PA translocation. All patients with tetralogy of Fallot with pulmonary atresia (TOF/PA) and double-outlet right ventricle (DORV) underwent anterior augmentation of the posterior native outflow tract.
2.3 Postoperative interventions
Indications for postoperative CBI included (1) a gradient across the RVOT of more than 40 mmHg, (2) significant PA stenosis with potential loss of branch PA flow or evidence of substantial disparity in pulmonary blood flow by radionucleotide perfusion scanning, and (3) elevated RV pressure with evidence of progressive RV dysfunction or tricuspid regurgitation, or both. The overall threshold for CBI was low given the deleterious effects of obstructive lesions in a valveless system and the desire to avoid reoperation.
Reoperation was indicated for the above parameters when CBI failed to restore acceptable hemodynamics, in lesions not amenable to percutaneous intervention, or when patients required surgery for some other indication.
2.4 Statistical analysis
Standard descriptive statistical methods were used. Data are presented as frequencies, median with ranges, and mean with standard deviations, as appropriate. To assess differences between groups, the Mann–Whitney test or Student's test for continuous data and the chi-square or Fisher's exact test for categorical data were used. Early death (operative mortality) was defined as death within 30 days after surgery or after 30 days but during the same hospitalization [8]. Analysis of risk factors for intervention (CBI, reoperation, or any intervention), mortality, and intervention-free survival was performed. Logistic regression and Cox regression models were applied to analyze significant risk factors in a multivariable manner. Kaplan–Meier methods were used to evaluate intervention-free survival, and p values for differences between distributions were obtained by log-rank testing. A value of p
< 0.05 was considered statistically significant.
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3. Results
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3.1 Patients
The median age at repair was 5 days (1–270 days) for the entire cohort. Twenty-six (76%) patients were neonates. Median weight at repair was 3.1 kg (1.8–7.3 kg). Median follow-up was 43 months (1–90 months). Follow-up was complete in 93% (28/30). Two patients were lost to follow-up after a median of 9 months (1–27 months).
3.2 Mortality
There were four (11.8%) early deaths, and the data for these patients are presented in Table 2
. Patients with TAC had the lowest survival (20% mortality, 3/15) versus all other patients (5.3% mortality, 1/19). Determined risk factors for early death included low weight at surgery (p
= 0.05) and need for preoperative mechanical ventilation (p
= 0.03). None of these factors reached significance in the logistic regression analysis.
3.3 Reinterventions
3.3.1 CBI
Seven (23%) patients underwent CBI at a median interval of 5.5 months (2–67 months) to first intervention. Three (10%) required more than one CBI for recurrent obstruction. The incidence of CBI was not significantly different according to diagnosis (Table 3
). Univariate analysis and logistic regression did not identify any risk factors for CBI.
3.3.2 Reoperation
Fifteen (50%) patients underwent reoperation for right-sided obstruction with zero mortality. The median interval to first reoperation was 16.5 months (3–43 months). Incidence of reoperation was similar for obstruction at the ventricular outflow and branch PA level. Almost half of patients (7/15) had multilevel obstruction. Two patients (6.7%) underwent additional surgeries for recurrent obstruction. At present, no patients have undergone reoperation for pulmonary insufficiency.
As shown in Table 3, patients with TAC were more likely to undergo reoperation (p
= 0.02). This difference was also significant by Kaplan–Meier estimates of freedom from reoperation (Fig. 1
). There were no other predictors of need for reoperation.
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Fig. 1. Kaplan–Meier survival function of freedom from reoperation for TAC and diagnosis other than TAC (p
= 0.04). TAC: truncus arteriosus communis; other: double-outlet right ventricle, transposition of the great arteries/ventricular septal defect/pulmonary stenosis, tetralogy of Fallot, tetralogy of Fallot with pulmonary atresia.
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3.3.3 Any reintervention (CBI or reoperation)
Sixteen (53%) patients required either CBI or reoperation during the follow-up period. The median interval to this combined end-point was 6 months (2–62 months).
Diagnosis of TAC was the only predictor of need for reintervention (p
= 0.04; Table 3). The Kaplan–Meier estimates of freedom from any reintervention also demonstrated a significant difference according to anatomic diagnosis (Fig. 2
).
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Fig. 2. Kaplan–Meier survival function of freedom from any reintervention for TAC and diagnosis other than TAC (p
= 0.05). TAC: truncus arteriosus communis; other: double-outlet right ventricle, transposition of the great arteries/ventricular septal defect/pulmonary stenosis, tetralogy of Fallot, tetralogy of Fallot with pulmonary atresia.
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4. Discussion
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Surgical repair of congenital heart defects requiring restoration of RV to PA continuity is increasingly performed in neonates and young infants. Complex forms of TOF, pulmonary atresia, TAC, TGA/VSD with PS, and certain forms of DORV are among the defects requiring creation of a pathway from the RV to the PAs. The optimal method of RVOT reconstruction in these patients remains a topic of considerable debate.
Establishing RV to PA continuity in neonates and young infants presents unique challenges. The ‘ideal’ conduit should restore normal hemodynamics, be non-thrombogenic, have growth potential, and function indefinitely (free from stenosis or regurgitation). To date, such a conduit remains elusive. Contemporary options for RVOT reconstruction are multiple and include the use of extracardiac conduits (homografts, heterografts, and conduits constructed with pericardial or prosthetic materials) as well as non-conduit reconstructions (direct anastomosis and interposition of autologous tissue).
Right ventricular outflow tract reconstruction with a homograft conduit is widely accepted as the method of choice in neonates and young infants because of a favorable hemodynamic profile and tissue handling properties that facilitate complex reconstructions with minimal bleeding. However, durable homograft conduit survival in neonates and infants has been disappointing. Reports suggest accelerated homograft failure in infants less than one year of age with a median time to reoperation of less than 3 years [9–11]. In addition, these grafts develop early progressive insufficiency. Chan et al. [12] reported that 50% of patients receiving a cyropreserved homograft for RVOT reconstruction before 18 months of age developed severe regurgitation by 15 months postoperatively. A recent prospective, multi-institutional Congenital Heart Surgeon's Society study of 241 children under 2 years of age who received a valved conduit in the pulmonary position identified smaller conduits, younger age, and presence of branch PA stenoses as risk factors for early reintervention [13]. In their report, freedom from any reintervention at 3 years was only 42%. By 4 years, 38% of children had undergone reoperation for conduit replacement. They concluded that if selecting a pulmonary-valved conduit in this age group, a Z-score between +1 and +3 results in optimal durability.
Due to the shortage and limited durability of small-diameter homografts, efforts persist in finding heterograft and non-conduit alternatives. Recently, there has been great enthusiasm for the use of a valved bovine jugular vein (Contegra conduit) in pediatric RVOT reconstruction. In addition to its widespread availability, the trileaflet valve suspended in the middle third of a long-segment pliable conduit offers incredible surgical versatility. Early reports demonstrated promising hemodynamic and clinical results, however, there are several recent reports of progressive structural degeneration particularly in younger age patients, smaller conduits and patients with elevated pulmonary artery pressures [14–17]. Comparisons to homograft performance in smaller patients are limited to a few retrospective reviews with short-term follow-up. Sinzobahamvya and colleagues recently reported similar outcomes of small-diameter Contegras and homografts after a mean follow-up of less than two years [18].
Non-conduit options have been developed for RVOT reconstruction that either avoid a valved conduit altogether or construct a conduit from the patient's own tissue. In all of these techniques, it is presumed that the autologous tissue pathway will grow with the patient and, therefore, limit reintervention secondary to somatic outgrowth. The reparation a l’etage ventriculaire (REV procedure), Nikaidoh aortic translocation, and the ‘half-turned truncal switch’ of Yamagishi et al. are all Rastelli alternatives that can be accomplished without the use of a valved conduit [19–21]. Reid et al. and Barbero-Marcial et al. introduced non-conduit reconstructions in patients with TAC by establishing a direct connection of the PA confluence to the ventriculotomy or by utilizing flaps of native tissue to create an autologous posterior floor [4,6]. Long-term results in Barbero-Marcial and Tanamati's series of patients with truncus arteriosus are excellent with actuarial freedom from reoperation of 89% at 11.4 years [22]. Chen and colleagues recently reported a decreased need for reoperation in truncus patients receiving a direct connection versus those who received a valved homograft [23]. In addition, they found a significant difference in outcomes among direct connection recipients according to hood type. Freedom from reintervention in patients who received a polytetrafluoroethylene hood was 80% at 5 years versus less than 20% for untreated autologous pericardial hoods.
In the present series, non-valved autologous RVOT reconstruction was used uniformly for primary repair of all neonates and infants requiring restoration of RV to PA continuity with the aim of reducing total number of reinterventions. Our finding that the diagnosis of TAC predicted the need for reintervention and reoperation contrasts with aforementioned reports of patients with TAC undergoing similar reconstructions [22,23]. This may be related to a number of factors including differences in age at repair, patient complexity, surgical techniques, and varying thresholds for CBI or surgical reintervention. We suspect the development of RVOT obstruction in our truncus population is related to technical aspects surrounding the autologous pathway reconstruction. In this particular anatomic subtype of conotruncal defects, there is a virtual absence of the subpulmonary infundibulum. During VSD closure, if the superior margin of the VSD patch is sewn directly to the epicardial junction of the PA and RV anastomosis, this will result in a fixed posterior circumference that does not grow with the patient. Furthermore, stenosis at this level is unlikely to respond to CBI and will require reoperation. As reported by Chen and colleagues, the type of hood or outflow patch may also be important [18]. We have noted during reoperations for RVOT obstruction that the pulmonary homograft outflow patches in our patients are often calcified and retracted. On the basis of these observations, we have modified our technique in patients with TAC so that the VSD patch does not extend to the epicardium of the posterior pathway. Additionally, we use bovine pericardium instead of homograft patch for the hood of our outflow tract reconstructions. Additional follow-up is necessary to determine the fate of these modifications.
Importantly, we found that non-truncus patients demonstrated a marked improvement in freedom from reintervention when compared with various reports of patients who received valved homograft reconstructions [11,13]. Additionally, it is notable that the Kaplan–Meier curves plateau, suggesting that a significant number of these patients may indeed remain free from reintervention due to obstruction. These findings support a strategy of autologous RVOT reconstruction as an alternative to small-diameter homografts or Contegra conduits in neonates and infants. However, further follow-up is necessary to conclude that autologous reconstruction results in durable freedom from reoperation.
As in other studies, our results suggest that CBI as a strategy of initial intervention for conduit stenosis may be advantageous in delaying or even reducing later reoperation [10,13,24,25]. One important advantage of autologous RVOT reconstruction is the presence of the posterior native tissue pathway that renders CBI feasible. Although the majority of patients undergoing CBI required multiple interventions, only half ultimately required reoperation. Again, additional follow-up is necessary to support a conclusion that CBI reduces the need for reoperation.
If a strategy of autologous reconstruction permits growth into adolescence, patients could then receive an adult-sized valved conduit that would possess a reasonable life expectancy and would eliminate the detrimental consequences of chronic pulmonary insufficiency. This could potentially limit the number of conduit reoperations over the lifetime of the patient. The results presented here support this concept in non-truncus patients. The higher reintervention rate observed in patients with TAC may be related to technical details associated with reconstruction of the posterior autologous pathway.
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Acknowledgments
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We thank Dr W.I. Norwood for his important contribution to the care and management of these patients and Dr Emilio Quezada for his assistance in preparation of this manuscript.
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Abstract
1. Introduction
