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Ann Thorac Surg 2001;71:489-493
© 2001 The Society of Thoracic Surgeons

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Original article: cardiovascular

Open commissurotomy for critical isolated aortic stenosis in neonates

^a Department of Cardiac Surgery, The General Hospital, Southampton, United Kingdom
^b Department of Paediatric Cardiology, The General Hospital, Southampton, United Kingdom

Accepted for publication July 15, 2000.

Address reprint requests to Dr J Monro, Department of Cardiac Surgery, The General Hospital, Tremona Rd, Southampton SO16 6YD, United Kingdom
e-mail: monro1711{at}aol.com

	Abstract

Top Footnotes Abstract Introduction Patients and methods Results Comment References

 
Background. The optimal management of critical aortic stenosis in early infancy remains controversial. The aim of this study was to assess the early and late outcomes following open surgical valvotomy for critical aortic stenosis in neonates and to provide a framework of data against which current results of other treatment approaches can be evaluated.

Methods. Eighteen consecutive neonates (mean age 9.2 days, range 1 to 26 days) undergoing an open valvotomy for critical isolated aortic stenosis (the standard treatment for this condition in our unit) between 1984 and 2000 were studied. The mean aortic valve gradient was 79.4 mm Hg. Twelve neonates received prostaglandins and 10 received inotropic agents preoperatively. Follow-up was complete (mean 8.1 years, range 1 month to 15 years).

Results. There was no operative mortality. At discharge, the mean aortic valve gradient was 37.2 mm Hg, with 6 patients having mild and 2 having moderate aortic regurgitation. Six patients required a reoperation; 3 of these had an aortic valve replacement at 9 to 11 years of age. Kaplan-Meier 5- and 10-year freedoms from any aortic reoperation or reintervention were 85 and 55%, respectively; 5- and 10-year freedoms from aortic valve replacement were 100 and 79%, respectively. A 14-year-old boy died from endocarditis 4 years following an aortic valve replacement in another unit. Kaplan-Meier 10-year survival was 100%. All survivors are in New York Heart Association I class and are leading normal lives. Their mean aortic valve gradient is 34.5 mm Hg, and none has significant aortic regurgitation.

Conclusions. Open valvotomy for critical aortic stenosis in neonates carries a low operative risk and provides lengthy freedom from recurrent stenosis or regurgitation. Reoperations are inevitable, but aortic valve replacement can be delayed until the implantation of an adult-sized prosthesis is possible. Late survival is excellent. We consider open surgical valvotomy to be the treatment of choice for critical neonatal aortic stenosis.

	Introduction

Top Footnotes Abstract Introduction Patients and methods Results Comment References

 
The selection of the most appropriate treatment approach for neonates with critical aortic stenosis remains controversial. Various types of surgery have been associated with high operative mortality in the past [1–3], but more recent reports suggest that surgical results are improving [4–8].

Percutaneous balloon valvuloplasty has been proposed as a less invasive option, and although it was initially linked with significant procedural morbidity and mortality, particularly in neonates [9, 10], it is now widely regarded as a safe and effective technique.

Although percutaneous balloon valvuloplasty is currently advocated by several centers as the procedure of choice [11–13], open surgical valvotomy under hypothermic cardiopulmonary bypass and cardioplegic myocardial arrest remains the standard approach in the management of critical neonatal aortic stenosis in our unit.

The aim of this study was to analyze the early and late outcomes achieved through this therapeutic strategy and to provide a framework of data against which current results of percutaneous balloon valvuloplasty can be evaluated.

	Patients and methods

Top Footnotes Abstract Introduction Patients and methods Results Comment References

 
Between January 1984 and May 2000, 25 consecutive neonates with critical aortic stenosis underwent open surgical valvotomy in Southampton.

Eighteen of these neonates, 15 boys and 3 girls, had "isolated" aortic stenosis, as previously defined [4] (aortic stenosis with or without aortic coarctation, atrial septal defect, or patent ductus arteriosus), and these 18 patients are the subject of this report. Their mean age was 9.2 days (range 1 to 26 days), with 12 of them being 1 to 11 days old. Mean body weight at operation was 3.2 kg (range 2.4 to 4.2 kg).

The remaining 7 neonates, 2 of whom died early, had hypoplastic left ventricles or other severe associated cardiovascular lesions. In order to obtain a homogeneous patient cohort for analysis, these 7 patients were excluded from this study.

Neonates presenting with critical aortic stenosis and hypoplastic ventricles or other severe coexisting cardiovascular problems tend to have a less favorable clinical course irrespective of the type of treatment they receive [14], and they may die from problems unrelated to the aortic valve. Their inclusion, thus, into the relevant studies is confusing and makes comparisons between various treatment modalities employed for neonatal aortic stenosis, eg, open surgical valvotomy versus percutaneous balloon valvuloplasty, difficult or even impossible [4].

Until 1995, neonates with small-sized hearts and critical aortic stenosis were, in this unit, treated with an open valvotomy in the hope that this course of treatment would allow the heart to grow. The management of this condition has since then evolved, and infants with echocardiographical evidence of hypoplastic left heart syndrome (aortic valve annulus < 5 mm, mitral valve annulus < 9 mm, and left ventricular inflow diameter < 21 mm) [15] are now managed with a Norwood type I palliative procedure.

Clinical features
Routine preoperative evaluation included physical examination and two-dimensional echocardiography with Doppler studies. All neonates presented with congestive heart failure of varying severity: 13 of them had impaired left ventricular function on echocardiography (ejection fraction less than 50%); 12 were receiving prostaglandin infusion; 10 required treatment with inotropic agents; and 6 were in a moribund condition, being hypotensive, acidotic (pH < 7.2) and anuric-oliguric. Mean aortic valve gradient immediately before the operation, while several patients were receiving inotropic support, was 79.4 mm Hg (range 33 to 120 mm Hg).

The operative procedures were emergency in 14 and urgent in 4 cases. The diseased aortic valve was bicuspid in 13 and tricuspid in 5 patients. Myxomatous and fibrous nodules on the surface of the aortic valve were present in 7 patients. Eight patients had additional intracardiac or extracardiac abnormalities. These were coarctation of the aorta in 3 patients, a small ventricular septal defect in 1, subaortic stenosis in 1, pulmonary valve stenosis in 1, atrial septal defect in 3, patent ductus arteriosus in 4, and mitral valve regurgitation in 2.

The operation
The operations were performed through a median sternotomy under hypothermic cardiopulmonary bypass (CPB), established through an ascending aortic and single atrial cannula. Myocardial protection was provided with cold crystalloid (St. Thomas‘s solution) or, more recently, with cold blood cardioplegia and topical hypothermia. After transverse aortotomy, the aortic valve was inspected and a commissurotomy to the aortic annulus was performed. In order to avoid the development of aortic regurgitation, the raphe of a bicuspid valve was not divided. Obstructive myxomatous and fibrous nodules on the aortic valvular surfaces were also excised.

Concomitant interventions included repair of coarctation of the aorta in 3 patients, closure of a ventricular septal defect and resection of subaortic stenosis in 1 patient, and ligation of patent ductus arteriosus in 4 patients.

Follow-up
Patients were seen in the outpatient clinic shortly after they left the hospital and at 3-, 6-, or 12-month intervals, as required. Two-dimensional echocardiography and Doppler studies were routinely performed before discharge from the hospital and during each outpatient visit by the pediatric cardiologists. Clinical information and echocardiographical data were available for all children at the closing date of this study (June 20, 2000). Follow-up was complete, averaging 8.1 years (range 1 month to 15 years), with a total of 145.8 patient years.

Statistics
Freedom from time-related events was calculated using the product-limit method of Kaplan-Meier. Means were compared with t test. The level of statistical significance was set at a p value of less than 0.05. Statistical analysis was done with the statistical package SPSS PC (version 8.0; SPSS Inc, Chicago, IL).

	Results

Top Footnotes Abstract Introduction Patients and methods Results Comment References

 
Operative mortality and morbidity
There were no operative deaths. Three patients needed intravenous infusion of inotropic agents for more than 48 hours after their operation as a result of their poor preoperative hemodynamic status, and 1 of these had renal dialysis. The remaining 15 neonates had an uneventful postoperative recovery.

Early functional outcome
Echocardiographical examination before discharge from the hospital demonstrated a good left ventricular function in 15 patients and impaired but improved—compared to the preoperative status—left ventricular contractility in 3 patients. The mean gradient across the aortic valve was reduced to 37 mm Hg (p < 0.0001), ranging from 0 to 50 mm Hg, with 6 patients having mild and 2 moderate aortic regurgitation.

Reoperations and reinterventions
Six patients had a reoperation or reintervention (3 for recurrent aortic stenosis and 3 for severe late aortic regurgitation), 2 to 10.8 years (mean 6.9 years) following their open valvotomy; there was no operative mortality with any of these reinterventions.

One patient developed recurrent aortic stenosis 24 months following his open valvotomy and underwent a percutaneous balloon valvuloplasty. Another patient developed recurrent left ventricular outflow tract obstruction at valvar and subvalvar level and had a repeat open valvotomy and resection of subaortic membrane 42 months after his initial operation. A third patient developed recurrent aortic stenosis and severe mitral regurgitation and underwent aortic valve repair with a patch of bovine pericardium using a technique that we have previously described [16] and mitral valve repair and annuloplasty 73 months following the open valvotomy. Kaplan-Meier 5- and 10-year freedoms from recurrent aortic stenosis were 85 and 77%, respectively (Fig 1).

View larger version (9K): [in this window] [in a new window]   Fig 1. Kaplan-Meier freedom from recurrent aortic stenosis at 5 and 10 years was 85 and 77%, respectively.

Kaplan-Meier 5- and 10-year freedoms from severe late regurgitation or AVR were 100 and 79%, respectively (Fig 2), and 5- and 10-year freedoms from any aortic valve reoperation or reintervention were 85 and 55%, respectively (Fig 3).

View larger version (9K): [in this window] [in a new window]   Fig 2. Kaplan-Meier 5- and 10-year freedoms from severe aortic regurgitation (AR) and aortic valve replacement (AVR) were 100 and 79%, respectively.

View larger version (9K): [in this window] [in a new window]   Fig 3. Kaplan-Meier freedoms from any aortic valvular reoperation (including cardiological reintervention) at 5 and at 10 years were 85 and 56%, respectively.

Kaplan-Meier 10-year survival for all patients was 100% (Fig 4). At latest clinical evaluation, all survivors (n = 17) were in New York Heart Association functional class I leading normal or near-normal lives. The mean aortic valve gradient on most recent echocardiography was 36.6 mm Hg (range 0 to 56 mm Hg), with 3 patients having trivial, 6 mild, and 5 moderate aortic regurgitation.

View larger version (8K): [in this window] [in a new window]   Fig 4. Kaplan-Meier survival function at 10 years was 100%. One patient underwent an aortic valve replacement elsewhere at 10 years of age and died 4 years later from endocarditis.

	Comment

Top Footnotes Abstract Introduction Patients and methods Results Comment References

Various types of surgery have been frequently associated with early death rates higher than 50% in the past [1, 2, 18].

Early outcome
The absence of early mortality in this consecutive series of 18 neonates with critical isolated aortic stenosis, 6 of whom were operated on in a moribund clinical condition, is most gratifying and reflects improvements made in the preoperative diagnosis with avoidance of invasive investigations, perioperative critical care, management of anesthesia, and surgical technique. It compares favorably with operative mortality rates reported from centers employing various surgical approaches or percutaneous balloon dilatation techniques [1–13] and supports recent reports that have also attested to a significant reduction of operative mortality (between 13 and 18%) following open surgical commissurotomy under CPB in neonates [4–8].

The perioperative morbidity was also acceptable, with the 3 patients developing complications mainly as a result of their poor preoperative hemodynamic status and responding well to usual therapeutic measures.

Reinterventions
Accepting that any type of treatment of aortic stenosis in neonates is palliative and that future AVR is inevitable, the success of such treatment should be judged, apart from its safety, by its ability to provide a lasting freedom from residual or recurrent stenosis while avoiding severe aortic regurgitation. Its ability to do so would delay the need for an AVR until the child grows enough so that the insertion of an adult-sized valve is possible.

Our experience has in this context been rewarding. No patient had a reoperation within 2 years following the open commissurotomy. Three children developed recurrent aortic stenosis 2 to 6 years postoperatively, and these children were treated successfully with a variety of techniques requiring no further interventions; furthermore, all patients were free from severe aortic regurgitation for the first 9 years following their operations (Fig 2).

The 3 children who developed severe aortic regurgitation necessitating an AVR did so at 9 to 11 years of age, with both of the 2 children who underwent an AVR in this unit receiving an adult-sized prosthesis. Moreover, there was no operative mortality at reoperation, and 12 of the 17 survivors are still free from any form of reintervention.

The actuarial 5-year freedom from any aortic reintervention of 85% (Fig 3) is good and compares favorably with 5-year freedoms from reintervention of 64 to 68% reported from institutions employing open valvotomy or transvascular balloon dilatation techniques [6, 8, 13].

Late survival
The late—up to 14 years—actuarial survival of 100% (Fig 4) was excellent and compares favorably with survival rates quoted following surgical or balloon aortic valvuloplasty in previous reports [1–13]. Perhaps more important, all patients are in New York Heart Association functional class I and enjoy normal or near-normal lives.

The late death of a 14-year-old child from valvular endocarditis, following a mechanical AVR elsewhere, was nevertheless very disappointing, particularly if one considers that none of the 56 children who underwent an AVR with mechanical prosthesis between 1973 and 1999 in this unit experienced such a complication [19].

Alternative options
Percutaneous balloon valvuloplasty has been introduced as a less invasive and safer treatment modality, partly as a response to high surgical mortality. In the first years of its application, the procedure was associated with major procedure-related morbidity, including transection of the femoral and iliac artery, perforation of the aorta, massive aortic regurgitation, perforation of the left ventricle, pericardial tamponade, perforation of the mitral valve, complete avulsion of the aortic valve, and mortality rates in excess of 50% [9, 10]. Increasing experience led to a reduction, but not to elimination, of these problems, with the vascular complications being even more pronounced in neonates [10–12]. Percutaneous balloon valvuloplasty has now became a technique that is safe and effective in reducing aortic stenosis, and in several institutions it represents the primary treatment for neonatal aortic stenosis [11–13].

Transventricular aortic dilatation, with or without CPB, is also being practiced in some centers reporting good early and late results [5].

The optimal management of critical aortic stenosis in the neonatal age remains highly controversial. Surgical and percutaneous techniques certainly have their merits and drawbacks, yet the variability in the makeup of the patients involved makes comparisons between different studies difficult. Because evidence produced through randomized controlled clinical studies is lacking, the choice of the most appropriate treatment is based on the analysis of local experiences and reflects the availability of relevant expertise.

We, in agreement with others, find that open commissurotomy under hypothermic CPB and cardioplegic cardiac arrest provides certain distinct physiologic and anatomic advantages [4, 6–8]. CPB allows for the myocardium to recover and for the deranged metabolic indicators to be corrected. It enables direct inspection of the aortic valve and facilitates the performance of an appropriate commissurotomy along with excision of obstructive myxomatous and fibrous nodularities from the surface and free edges of the aortic valve [6–8, 14]. This is not achievable with any of the "blind" methods of aortic dilatation techniques currently in use. The careful division of fused cusps over even as little as 1 or 2 mm can greatly increase the cross-sectional area of the valve and can thus allow a marked increase in the cardiac output. We believe that our surgical technique accounts for the low incidence of early recurrent aortic stenosis (5-year freedom of 85%) and the complete lack of early and midterm clinically significant aortic regurgitation (up to 9 years freedom of 100%) among our patients. The latter compares very favorably with the balloon valvuloplasty series, in which some patients invariably develop severe aortic regurgitation in the early postoperative period [9–13].

In conclusion, open surgical valvotomy for critical aortic stenosis in neonates can be accomplished with low operative risk, providing lengthy freedom from aortic valvar restenosis and regurgitation.

In these young patients, reinterventions are ultimately unavoidable, but AVR can be delayed until the implantation of an adult-sized prosthesis is possible. The survival expectancy for the neonates with isolated aortic stenosis is excellent.

Based on the results of this study, we believe that open surgical valvotomy under hypothermic cardiopulmonary bypass and cardioplegic myocardial arrest remains the treatment of choice for critical neonatal aortic stenosis.

	Footnotes

Top Footnotes Abstract Introduction Patients and methods Results Comment References

 
This article has been selected for the open discussion forum on the STS Web site: http://www.sts.org/section/atsdiscussion/

	References

Top Footnotes Abstract Introduction Patients and methods Results Comment References

 

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This Article Abstract Full Text (PDF) Online Discussion 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): Christos Alexiou James L. Monro Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Alexiou, C. Articles by Monro, J. L. Search for Related Content PubMed PubMed Citation Articles by Alexiou, C. Articles by Monro, J. L. Related Collections Congenital - acyanotic Valve disease