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Ann Thorac Surg 2003;75:132-137
© 2003 The Society of Thoracic Surgeons

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Original article: cardiovascular

Biventricular repair after Norwood palliation

^a Department of Pediatric Cardiothoracic Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA
^b Department of Pediatric Cardiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA

* Address reprint requests to Dr Pearl, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Ave, OSB-3, Cincinnati, OH 45229, USA
e-mail: pearj0{at}chmcc.org

Presented at the Thirty-eighth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2002.

	Abstract

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BACKGROUND: In general, neonates with severe left ventricular outflow tract obstruction, aortic valvar stenosis or atresia, and arch hypoplasia with either interruption or coarctation, and a small left ventricle undergo Norwood palliation followed classically by a bidirectional cavopulmonary shunt and eventual modified Fontan. However, a subset of patients, usually neonates with a ventricular septal defect, may have adequate left ventricle and mitral valve sizes making them candidates for future biventricular repair (BVR). In view of the long-term advantage of BVR, the feasibility and outcome of this approach was studied. Additionally, echocardiographic data were reviewed in an attempt to develop objective prognostic criteria for selection of patients suitable for BVR.

METHODS: During a 4-year period, 8 of 58 infants undergoing Norwood palliation were identified as potential two-ventricle candidates. Their mean age was 6 days. Diagnoses included aortic atresia (n = 1), or aortic valve stenosis and subaortic stenosis (n = 7), with an interrupted aortic arch in 3 and coarctation in 4. All patients had a ventricular septal defect and a left ventricle that was considered to be apex forming. Mean mitral valve size was 11 mm (z-score = -1.7). Mean aortic valve size was 4.1 mm (mean z-score = -8.4).

RESULTS: All 8 patients survived Norwood palliation. Six subsequently underwent BVR with ventricular septal defect closure and a right ventricle to pulmonary artery conduit at a mean age of 7 months. One patient is awaiting repair, and 1 underwent a cavopulmonary shunt. At the time of BVR, mean mitral valve z-score was essentially unchanged at -1.4 (14 mm). No early deaths or late deaths occurred during a mean follow-up of 32 months.

CONCLUSIONS: A small subset of patients requiring Norwood palliation as newborns may be candidates for eventual BVR with low risk. In general, patients suitable for BVR have a mitral valve z-score of more than -3 and a normal-sized left ventricle. Recognition of neonatal BVR candidates enables consideration of complete neonatal repair. However, single-stage repair needs to be compared with the excellent results obtainable with the staged approach.

	Introduction

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Neonates with severe left ventricular outflow tract obstruction (LVOTO), aortic valvar stenosis or atresia, and aortic arch hypoplasia or interruption and a small left ventricle (LV) typically undergo Norwood palliation. These patients then follow a single ventricle pathway, undergoing subsequent Glenn and modified Fontan palliation. However, a subset of patients, usually those with a ventricular septal defect (VSD), may have adequate LV and mitral valve sizes, thus making them candidates for future biventricular repair (BVR) [1–3]. Biventricular repair consists of a Rastelli-type procedure either concomitantly or as a staged approach.

In view of the long-term survival and functional advantage of BVR, identification of potential candidates is critical. However, objective criteria to determine suitability are lacking, leading to a subjective and sometimes random selection of eligible patients. Failure to identify potential candidates prospectively may result in unnecessary long-term single-ventricle palliation in some patients. A wide spectrum exists among patients with left-sided obstructive disease [1]. At the mildest end of the spectrum is coarctation with VSD, which may be associated with mild LVOTO. This group is typically managed successfully with arch repair and VSD closure, either simultaneously or staged [2, 3]. Techniques for anchoring the VSD patch to the left side of the septum to reduce LVOTO have been successful [4]. For more severe degrees of aortic root hypoplasia, a Ross-Konno procedure may be considered in conjunction with arch repair [5–8]. At the most severe end of the spectrum a modified Norwood operation is advocated combined with a Rastelli procedure in a simultaneous or staged fashion.

Other than a recent reported series by Ohye and colleagues, reported experience with a combined Norwood-Rastelli approach is limited to a few reports of 1 or 2 patients [9–11]. Whether a staged approach or single-stage complete BVR provides superior early and late outcome is unclear. Furthermore, few objective criteria are available to help identify the proper pathway for these patients. In an effort to identify objective neonatal echocardiographic data predictive of successful BVR, as well as to determine the outcome of this staged approach, we reviewed our experience with patients undergoing Norwood palliation followed by Rastelli-type repair.

	Material and methods

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During a 4-year period, June 1997 through June 2001, 8 neonates from a total of 58 undergoing Norwood palliation were identified at the time of surgery as potential two-ventricle candidates based on LV and mitral valve size. A retrospective review was carried out, with patients identified from neonatal echocardiography and pre-Norwood surgeon notation. The average age was 6 days (3–14 days), and the average weight was 3.1 kg (2.6–3.4 kg). Diagnoses included either aortic atresia [1] or aortic valve stenosis/subaortic stenosis [7], with interrupted aortic arch in 3 patients and coarctation in 4. All patients had a VSD and an LV that was thought to be near normal in size and apex forming (Table 1). The aortic valve was measured in the parasternal long-axis view, and the mitral valve was measured in the apical four-chamber view. The mean aortic annular diameter was 4.1 mm (3.5–4.7 mm) with a mean aortic valve z-score of -8.4 (-6.1 to -10). The mean mitral annular diameter was 11.1 mm (8–14 mm) with a mean z-score of -1.6 (0 to -3.2) as determined using z-score values as published by Daubeney and colleagues [12] (Table 2). The left ventricular outflow tract was a mean of 3.6 mm (3.0–4.3 mm). Aortic arch hypoplasia was present in all patients. A modified Norwood procedure was performed in all patients using a patch for arch augmentation in 7, and direct anastomosis in 1. The mean myocardial ischemic time was 73 minutes and the cardiopulmonary bypass time was 183 minutes. Five patients underwent circulatory arrest for an average time of 62 minutes. Low-flow regional perfusion was used in 3 patients (Table 1).

	Results

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All 8 patients survived Norwood palliation. Six have subsequently undergone BVR with VSD closure and placement of a right ventricular to pulmonary artery conduit, Rastelli-type procedure, at a mean age of 7 months (4–11 months). The VSD was enlarged in all patients at the time of the Rastelli procedure. Two patients required simultaneous aortoplasty for recurrent arch stenosis (Table 2). To facilitate conduit placement, a LeCompte maneuver was performed in 1 patient and the conduit placed to the right of the aorta in 3 patients.

At BVR the mitral valve annulus had increased in all patients (mean = 14 mm), with the z-score essentially unchanged (mean z-score = -1.4). Hence, mitral valve size relative to body surface area remained essentially unchanged (Table 3). Surprisingly, aortic cross-clamp (132 minutes) and bypass times (226 minutes) were fairly long during the Rastelli procedure. The mean conduit size was 13.6 mm (9–16 mm). Cryopreserved homografts were used in all patients. One of the 8 patients subsequently underwent implantation of a cavopulmonary shunt and atrial septectomy at 5 months of age. This patient was the only one with an initial mitral valve z-score less than -2.5 (-3.2) and at time of cavopulmonary anastomosis had a mitral z-score of -4.1 (8.5 mm diameter). The valve also appeared to be parachute, and the LV not quite apex forming, findings that were not clear from the neonatal echocardiogram. In retrospect, this patient would not have been considered a likely future BVR candidate using our current criteria. The final patient is doing well 8 months after Norwood palliation and appears to be a suitable BVR candidate. There were no early deaths or late deaths during a mean follow-up of 32 months.

	Comment

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Using the echocardiographic data from the 20-patient comparison group in conjunction with the values obtained from the patients undergoing Norwood-Rastelli procedures, we have attempted to stratify neonates presenting with left-sided obstructive disease and adequate LV size. Our data demonstrate the following points: (1) In patients with coarctation-VSD and good LV size, mitral valve size is rarely prohibitive, if structurally normal, ie, nonparachute shaped. (2) Mitral valve size compared with body surface area remains relatively unchanged after surgical intervention. This outcome is important in that a policy of waiting to see if the mitral valve size will increase to guide therapy is unwarranted. Neonatal mitral valve z-score correlates with future mitral valve size and adequacy. (3) An aortic valve and LVOTO size of 4 mm or less or a z-score less than -5 to -6 suggests that early management of the left-sided obstruction by using the pulmonary valve with either a Ross-Konno or Norwood procedure should be considered. (4) Certainly, an aortic valve z-score of less than -8 indicates the need for Norwood arch reconstruction with either simultaneous or staged Rastelli-type repair (Fig 1).

View larger version (20K): [in this window] [in a new window]   Fig 1. A suggested pathway to help guide management of neonates with complex left-sided obstructive disease, in whom a normal size left ventricle exists. Actual decision making should be individualized for each patient and according to preference and experience of surgeon and center with various approaches. (Abnl = abnormal; CoA = coarctation of the aorta; BVR = biventricular repair; LVOTO = left ventricular outflow tract obstruction; MV = mitral valve; nl. = normal; SV = single ventricle; VSD = ventricular septal defect.)

Arguments against a staged approach focus primarily on the morbidity and mortality of the Norwood procedure and to a lesser degree the relatively tenuous state of shunt-dependent infants [9, 10, 15]. However, with current modified Norwood mortality rates at less than 15% in low-risk patients, this argument is less germane [17, 18]. One would expect this group of patients to tolerate the Norwood physiology best due to the existence of two normal-sized ventricles contributing to cardiac output. Furthermore, the cumulative mortality for a combined approach must be compared with that for complete repair at the same institution. Although we have not yet undertaken complete neonatal repair in these patients, it would be hard to improve on our results so far, albeit the numbers are small. Our experience with neonatal or infant Ross-Konno procedures with concomitant arch repair has demonstrated considerable postoperative morbidity including the need for postoperative extracorporeal membrane oxygenation support in some patients.

Ohye and colleagues [9] demonstrated good outcome with a Norwood-Rastelli approach either as a staged procedure or when performed concomitantly. Proponents of complete neonatal repair cite the generally accepted concept that the sooner an infant attains a noncyanotic state, and the sooner volume or pressure overload is relieved, the better the long-term outcome will be [9]. Although this concept has considerable merit and is being applied to many congenital heart defects, the magnitude of complete repair when extensive arch reconstruction is needed must be considered.

As discussed above, a main argument against complete neonatal repair relates to the extensive myocardial ischemic time and bypass time that the neonatal immature myocardium would undergo [10, 11, 15]. The addition of a ventriculotomy may further comprise ventricular function in this group of patients. Conduit placement can be difficult because of the large anteriorly placed neo-aorta and the posterior pulmonary arteries. A LeCompte maneuver may be useful, and alternatively the conduit on occasion can be placed to the right of the neo-aorta. With neonatal conduit placement, conduit replacement within 3 to 4 years is expected. Therefore, with either approach it is likely that these patients will have two operations and two bypass runs within their first 3 years of life.

Previous publications regarding Norwood palliation of potential BVR patients and performance of the Rastelli procedure in this group of patients have discussed specific technical details. The few salient points include (1) leaving the atrial septal defect restrictive during the Norwood procedure to encourage left heart output, (2) enlargement of the VSD at the time of the Rastelli procedure, and (3) flexibility in conduit placement including placing the conduit to the right of the aorta or performing a Lecompte maneuver, particularly in the event of an interrupted aortic arch.

Whatever approach the surgeon takes, patients with diagnoses other than hypoplastic left-heart syndrome who undergo neonatal Norwood palliation should be reevaluated for suitability for BVR. Careful echocardiographic examination with detailed measurements of aortic and mitral valve size is critical for identifying BVR candidates and guiding operative techniques. In general, mitral valve size relative to body surface area remains unchanged, and the aortic valve z-score and size of the left ventricular outflow tract are most predictive. The limited experience available suggests that for newborns in whom BVR may be feasible, a staged approach and complete neonatal repair may each provide acceptable results.

	Discussion

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DR FRANK A. PIGULA (Pittsburgh, PA): I have a few questions for you. One is, did you have to enlarge the VSD in any of these patients prior to your definitive biventricular repair? My second question is, was there any advantage to a Ross-Konno procedure compared with simply baffling the VSD to the pulmonary outflow tract and incorporating it into a Norwood-type repair?

My last comment is that if you can do the Norwood operation, you can do the entire operation in the neonatal repair. I think the entire operation is preferable, particularly because of the high-risk, vulnerable postoperative period.

DR PEARL: I forgot to mention, the VSDs were enlarged in all 8 patients. I think in a study that Dr Bove conducted in which two groups were compared that had either a staged or biventricular approach, at least 80% of the patients also had enlarged VSD. Ensuring an unobstructed pathway from the LV is crucial.

We have performed few neonatal Ross-Konnos procedures. At least 1 patient needed extracorporeal membrane oxygenation after the operation. It would be worthwhile to compare a neonatal Norwood-Rastelli, as a combined neonatal approach, with a Ross-Konno, to determine which procedure would be superior. We do not have enough numbers or experience to know which is a better approach. I think leaving the pulmonary valve in place has some advantages in terms of its long-term function as a systemic valve.

DR SHINTARO NEMOTO (Houston, TX): Congratulations on your wonderful and interesting report. Two questionsneed to be answered in this study. First, I assume that you propose z-score of mitral valve size as a selection criterion for the staged biventricular repair after Norwood palliation. Because volume-overload in the physiology after Norwood palliation could cause eccentric ventricular hypertrophy along with an increase in the size of the mitral valve, it is important to address LV function and geometry as well as mitral size. Do you have any information regarding LV geometry, such as z-score of LV dimensions and mass, and correlation of z-score between mitral and LV dimensions in your patients? Second, reports from the Montreal Children’s Hospital showed that successful single-staged biventricular repair (Norwood + Rastelli) was achieved in a subset of patients with smaller mitral valve (z-score = -2.4). Do you have any comments about the evaluation and selection process for the single-staged or the staged biventricular repair?

DR PEARL: As I said, echocardiographically for the left ventricles, we use as a guideline that they are apex forming, which is more subjective in terms of the size of the LV cavity. Various programs can be used echocardiographically or angiographically, but the actual cavity size varies widely. We take it on faith that the left ventricle is apex forming and looks subjectively like a decent size. Thus I do not have any data comparing that to the mitral valve size in terms of some of the ratios that have been reported.

DR ALI DODGE-KHATAMI (Utrecht, The Netherlands): I have two questions. There was a good study published about a year ago by Dr Tehervenkov from Montreal, using the presence of antegrade flow in the ascending aorta as the major criteria to proceed with biventricular repair, instead of mitral valve z values and other echocardiographic numbers that your cardiologist would have to calculate for you. Have these criteria been useful to you in any instance? Also, do you think a Norwood operation could have been avoided in any of these infants?

DR PEARL: I think when most of the patients have a patent ductus and are taking prostins preoperatively, defining antegrade flow is difficult. Some forward flow may be detected, but whether that ventricle and that valve could handle a complete cardiac output is really unknown. One of the difficulties you run into when a patient has a patent ductus that is supplying part of the systemic outflow, you do not have a good way of knowing the capabilities of the left ventricle and the mitral and aortic valves.

The one point that was reassuring is that the mitral valve sizes did not seem to be a big issue as long as they were a reasonable size and the valve was normal. For the one patient whose z-score actually worsened, the preoperative echocardiogram did not reveal an abnormal mitral valve, but later echocardigrams revealed a parachute-looking valve, which would have put them in a different category.

DR JOHN E. MAYER, JR (Boston, MA): Do I take it then that in none of these patients were you able actually just to close the VSD to the aorta and then undo the pulmonary artery to aortic anastomoses?

DR PEARL: Correct.

DR MAYER: Then there clearly must have been, during this same time period, a group of patients who did have that as a primary repair. In other words, for interrupted arch VSD, there were a group of patients who had the VSD or atrial septal defect closed and had their arch repaired. How do you select your patients for that kind of repair versus this staged approach? And at what point do you become too nervous, shall we say, to attempt a two-ventricle repair with the LV outflow tract as the only egress from the left ventricle?

DR PEARL: We did not look specifically at only primary repair of the coarct-interrupted arch, although we have several such patients whom we could have included. From our experience, LV outflow tract sizes of 4 or 4.5 mm or smaller are a bit concerning. With an aortic valve z-score of around minus 5 or 6, I would feel nervous planning interrupted arch VSD repair without doing something else. We tried that in one patient and ended up doing a Ross-Konno within a few weeks because of high LV pressures. The patient was okay, but had a 60-mm gradient.

	References

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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Jeffrey M. Pearl Peter B. Manning Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pearl, J. M. Articles by Manning, P. B. Search for Related Content PubMed PubMed Citation Articles by Pearl, J. M. Articles by Manning, P. B. Related Collections Congenital - cyanotic