Ann Thorac Surg 2007;84:594-598
© 2007 The Society of Thoracic Surgeons
Original Articles: Cardiovascular
Outcome of Surgical Commissurotomy for Aortic Valve Stenosis in Early Infancy
Pia Rehnström, MDa,
Torsten Malm, MD, PhDa,*,
Peeter Jögi, MDa,
Eva Fernlund, MDb,
Per Winberg, MD, PhDc,
Jens Johansson, MDa,
Sune Johansson, MDa
a Pediatric Cardiac Surgical Unit, Children’s Hospital, University Hospital, Lund, Sweden
b Pediatric Cardiology Unit, Children’s Hospital, University Hospital, Lund, Sweden
c Pediatric Cardiology Unit, Astrid Lindgren Children’s Hospital, Stockholm, Sweden
Accepted for publication March 29, 2007.
* Address correspondence to Dr Malm, Pediatric Cardiac Surgical Unit, University Hospital, Lund, 221 85, Sweden (Email: torsten.malm{at}skane.se).
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Abstract
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Background: The method of treatment of aortic valve stenosis in early infancy is still controversial. This study was performed to evaluate short-term and long-term outcome in our center during a 14-year period.
Methods: Between 1991 and 2004, 64 consecutive patients younger than 3 months old underwent open surgical commissurotomy because of aortic valve stenosis. Median age was 18 days (range, 1 to 79 days), and median weight was 3.6 kg (range, 1.9 to 6.7 kg). Left ventricular function was good in 44 patients (69%), depressed in 12 (19%), and poor in 8 (12%). The study ended in July 2005. Median follow-up time was 4.1 years (range, 0.4 to 13.6 years).
Results: The 30-day mortality was 3 of 64 patients and late mortality was 3 of 61, and the respective mortality in patients younger than 1 month old was 2 of 41 and 2 of 39. There was no early mortality after 1993 and no late mortality after 1999. Thirteen patients required reoperation. Median time to reoperation was 4.3 years (range, 0.2 to 11.3 years) and to aortic valve replacement (7 Ross and 1 homograft) was 6.9 years (range, 1.6 to 9.7 years). At the last follow-up, all had good left ventricular function and 57 of 58 had an ability index of 1.
Conclusions: Surgical commissurotomy for aortic valve stenosis during the first 3 months of life can be done with low mortality and morbidity. The risk for early recurrent stenosis or regurgitation is low, and the need for aortic valve replacement can, in most cases, be delayed until the child is older. The long-term functional ability is excellent.
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Introduction
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The treatment of aortic valve stenosis in the neonate is still controversial, mainly because the mortality and morbidity after surgical valvotomy has been high in the past. Many centers have chosen percutaneous balloon dilatation as their treatment of choice. At the Pediatric Cardiac Surgical Unit, University Hospital, Lund, Sweden, open commissurotomy is the standard procedure, and we decided to analyze the mortality, morbidity, and the outcome of the valve itself over time. Our hypothesis was that the necessity for valve replacement could be delayed by the more precise opening of the valve performed by open commissurotomy.
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Patients and Methods
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This was a retrospective study of all patients who underwent operation because of aortic valve stenosis within the first 3 months of life at our institution from 1991 until 2004. The patients’ files were reviewed for data, including echocardiographic findings preoperatively, perioperatively, direct postoperatively, 6 to 12 months postoperatively, and at the patient’s last follow-up visit at the referring cardiologist. The study period ended in July 2005. Follow-up time was a median of 4.1 years (range, 0.4 to 13.6 years).
The study was approved by the Ethics Committee at the University Hospital in Lund. Because the study was retrospective, the committee waived the need for parental consent.
Patients
We identified 64 patients (47 boys, 17 girls). The median age at operation was 18 days (range, 1 to 79 days), and the median weight was 3.6 kg (range, 1.9 to 6.7 kg). Forty-one patients were neonates operated on within the first month of life, and 23 were infants who had their operation when they were between 1 and 2.5 months old.
A patent ductus arteriosus was found in 18 patients, 5 patients had an atrial septal defect, 2 had coarctation of the aorta, 1 had a stenosis of the left pulmonary artery branch, and 1 had a ventricular septal defect. Two patients underwent repair of aortic coarctation before the aortic valve procedure.
As assessed by echocardiography, left ventricular function was good in 44 patients (69%), depressed in 12 (19%), and poor in 8 (12%). At diagnosis, 34 patients (53%) presented with tachypnea, of whom 10 (16%) required ventilator; 10 (16%) were receiving prostaglandin therapy, 5 (8%) needed inotropic support, 4 (6%) had oliguria preoperatively, and 5 (8%) were acidotic on admission.
Intraoperatively, 55 patients (86%) were diagnosed with a functional bicuspid valve, 8 (12%) had a tricuspid valve, and 1 (1.6%) had a unicusp.
Surgical Technique
The operations were done with hypothermic cardiopulmonary bypass (CBP) using cardioplegia in all but 4 patients. Until 2000, crystalloid cardioplegia was used, but since 2001, blood cardioplegia has been the method of choice in our department. In most patients, CPB was started with reperfusion 10 to 15 minutes before clamping the aorta. This allowed the heart to beat with low filling pressure. Through an aortotomy, the fused commissures were incised and the valve was opened as much as possible, without risking severe aortic regurgitation. In 11 patients, the raphe corresponding to an undeveloped third commissure was incised. Shaving of the leaflets was only performed in one case.
Concomitant patent ductus arteriosus ligation or division was done in 18 patients, and 5 patients had atrial septal defect closure.
Follow-Up
Transthoracic echocardiography was performed by a pediatric cardiologist postoperatively before discharge from our hospital. The patients were then examined by the referring cardiologists at regular intervals. The echocardiographic data for the study were taken from the cardiologists’ reports. The left ventricular function was judged as good, depressed, or poor by using visual impression and usually the M-mode shortening fraction. The degree of aortic regurgitation (AR) was judged by the pediatric cardiologist as mild, moderate, or severe. This evaluation was determined by the total echocardiographic picture, usually including the width and length of the regurgitant jet into the left ventricle, the size of the left ventricle, the presence or absence of regurgitant diastolic flow in the aortic arch, and pressure half time.
Because the study was retrospective, the pediatric cardiologists’ evaluations were accepted, and no other exact criteria were used for quantification. In this study, we have obtained data 6 to 12 months postoperatively and at the latest visit to the pediatric cardiologists. Median follow-up time was 4.1 years (range, 0.4 to 13.6 years). Data were acquired from all study patients. The study period ended in July 2005.
Statistical Analysis
Data are presented as mean or median with range. Long-term results are presented with Kaplan-Meier curves calculated with the StatView program (SAS Institute Inc, Cary, NC).
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Results
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Mortality
The study period was divided into three time intervals: 1991 to 1995, 1996 to 2000, and 2001 to 2004. Figures for early mortality (within 30 days postoperatively) and late mortality are presented in Table 1. During the whole study period, the early mortality rate was 3 (5%) of 64 patients:- • In 1991, a 63-day-old girl presented with tachypnea and poor left ventricular function. Inotropic support was initiated and she received mechanical ventilation before undergoing open commissurotomy. Perioperatively, the surgeon noted signs of several myocardial infarctions, and the ventricular function was so poor that it was not possible to wean her off cardiopulmonary bypass.
- • In 1992, a 2-day-old boy, weighing 2.0 kg, presented with dilated left ventricle and poor contractions. He was receiving mechanical ventilation and prostaglandin therapy. An open commissurotomy was performed, and the sternum was left open owing to the dilated, bad ventricle. He died in the intensive care unit on the first postoperative day from low cardiac output.
- • In 1993, an 8-day-old girl, weighing 3.0 kg, presented with very depressed left ventricular function, fibroelastosis, and a small mitral valve without chordae. She underwent an open commissurotomy, and signs of myocardial infarctions were seen perioperatively. Peritonitis and sepsis developed postoperatively and she died 24 days later.
Late mortality for the whole study period was 3 (5%) of 61 patients. Late mortality occurred between 1.5 and 12.5 months postoperatively:- • In 1992, a 44-day-old boy, weighing 3.4 kg, with poor left ventricular function, a small left ventricle, and a hypoplastic ascending aorta underwent commissurotomy on fibrillating heart without cardioplegia. Postoperatively, he had low cardiac output, severe left ventricular failure, acidosis, and bradyarrhythmias, and he died after 39 days.
- • Also in 1992, a 1-day-old boy, weighing 2.6 kg, presented with poor left ventricular function, fibroelastosis, and pulmonary hypertension. He was operated with open commissurotomy on a fibrillating heart. Postoperatively, he had severe AR, pulmonary hypertension, low cardiac output, and sepsis developed. He died 1 year postoperatively.
- • In 1999, a 5-day-old boy, weighing 3.5 kg, presented with poor left ventricular function and an undersized left ventricle. Postoperatively, he had mild AR, low cardiac output, and pulmonary hypertension developed. He died after 5.5 months. An autopsy showed fibrosis of the pulmonary vessels, hypertrophy of the right ventricle, and extended fibroelastosis of a hypoplastic left ventricle.
The 10-year survival after commissurotomy was 90% (Fig 1).
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Fig 1. Kaplan-Meier survival (line) after open surgical commissurotomy was 90% at 1 year, 90% at 5 years, and 90% at 10 years.
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Valve Pathology
The maximum gradient across the aortic valve preoperatively, assessed with echo Doppler investigation and calculated with the Bernoulli equation, was a median of 100 mm Hg (range, 30 to 204 mm Hg) in 52 patients. Some of the lower gradients were recorded in patients with poor left ventricular function. At discharge, the median peak systolic gradient was 32 mm Hg (range, 9 to 99 mm Hg) in 58 patients and was 40 mm Hg (range, 11 to 125 mm Hg) in 55 patients at 6 to 12 months postoperatively. At the latest follow-up or at the time of the first reoperation, the median peak systolic gradient was 39 mm Hg (range, 11 to 135) in 58 patients, with a median follow-up time of 3.6 years (range, 2 months to 11.8 years; Fig 2).
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Fig 2. Maximum gradient across the aortic valve in patients operated with open surgical commissurotomy. Each line represents one patient.
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At discharge, 87% (53/61) had nonsignificant AR, 13% (8/61) had moderate, and no patients had severe AR. At 6 to 12 months postoperatively, 76% of the surviving patients (45/59) still had nonsignificant AR, 22% (13/59) had moderate, and 2% (1/59) had severe AR. The patient with severe AR later died. At the latest follow-up or at the time of reoperation, the respective figures were 67% (39/58), 24% (14/58), and 9% (5/58; Fig 3). Median follow-up was 4.1 years (range, 2 months to 11.8 years).
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Fig 3. Aortic regurgitation (clear bar, severe; solid bar, moderate; patterned bar, nonsignificant) over time in patients operated with open surgical commissurotomy.
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Reintervention
Reoperation was required in 13 of the 58 surviving patients; of which, seven were due to restenosis, three to a combined valve disease, and three to AR. Median time was 4.3 years (range, 0.2 to 11.3 years) to the first reoperation and 6.9 years (range, 1.6 to 9.7) to aortic valve replacement (7 Ross and 1 aortic root replacement with homograft). There was no mortality related to the reintervention procedure. One patient that needed reoperation at 9 months of age had a transcatheter balloon valvotomy done 3 months after the first commissurotomy. No prosthetic valves were inserted in any of the patients.
Freedom from reoperation was 95% at 1 year, 84% at 5 years, and 47% at 10 years. Freedom from aortic valve replacement was 100% at 1 year, 92% at 5 years, and 57% at 10 years after surgical commissurotomy (Fig 4
and Fig 5).
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Fig 4. Kaplan-Meier freedom from reintervention (line) after open surgical commissurotomy was 95% at 1 year, 84% at 5 years, and 47% at 10 years.
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Fig 5. Kaplan-Meier freedom from aortic valve replacement (line) with a Ross procedure or aortic root replacement after open surgical commissurotomy was 100% at 1 year, 92% at 5 years, and 57% at 10 years.
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A repeat commissurotomy was done in 7 patients due to aortic valve stenosis. Indications for reoperation with a Ross procedure were AR in 3 patients and combined aortic stenosis and regurgitation in 4 patients. One patient was initially treated with an open commissurotomy, but restenosis developed and he underwent percutaneous balloon dilatation 3 months later. Half a year after this procedure, severe mitral stenosis developed and a prosthetic valve was inserted in the mitral position. At the time of this operation, he also had a repeat commissurotomy owing to a residual aortic stenosis. At 1.5 years of age, severe aortic stenosis once again developed and he received an aortic root replacement with a homograft.
All 58 surviving patients had good left ventricular function at the last follow-up, and 57 of 58 had an ability index of 1 (Table 2) [1]. One patient had grade 2 due to a neurologic handicap, probably related to premature birth and an intracerebral hemorrhage preoperatively.
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Comment
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Significant aortic valve stenosis in the newborn is a serious condition with high mortality in older series. This study shows that open commissurotomy in the neonate can currently be done with low mortality. Other centers also report very low or no early mortality in this group of patients treated surgically [2, 3], but with increased risk in patients with other associated cardiac lesions [4]. As other authors have suggested [5], one reason for a better outcome during the last decade, both after balloon dilatation and open commissurotomy, most likely is better patient selection regarding ventricular size. Earlier diagnosis, better preoperative management, technical improvements, and improved perfusion techniques have also improved outcome.
We have used blood cardioplegia in our institution since 2001. During the study period, there was a gradual increase of perfusion flow, resulting in a decreased need for hypothermia. In these last years, we have used cerebral oximetry in all patients to assess the cerebral and kidney perfusion during bypass, allowing for adjustments if necessary.
The selection process for biventricular repair or a Norwood procedure in patients with left ventricular outflow obstruction is of great importance [6–8] and will affect the outcome. We found that two thirds of the late deaths in our study group could be explained by problems associated with hypoplasia of the left ventricle. Studies have shown that due to the considerable variability within the patient group, prediction of outcome is best made by combining the risk factors of small inflow, outflow, and left ventricular size [7, 8], and these are the factors we base our decisions on.
In patients with the duct still open, retrograde flow in the ascending aorta is of importance and supports a decision for univentricular repair. During the study period, 4 patients (not included in this report) presented with small left ventricular size, aortic stenosis, and retrograde flow in the ascending aorta. They underwent Damus-Kaye-Stansel anastomosis.
One patient included in the study had a marginal left ventricle, aortic stenosis, and retrograde flow in the ascending aorta. As reported previously in the article, a mitral stenosis developed, and he later received a mechanical valve in the mitral position and aortic root replacement with a homograft. At 3 years of age, his left-sided structures still have not developed to normal size. We believe that retrograde flow in the ascending aorta has a poor prognosis regarding biventricular repair.
Percutaneous balloon dilatation is the treatment of choice in many centers. The reported early mortality is 0% to 46%, depending on age group, center, and follow-up time [9–15]. During the study period, no percutaneous balloon dilatations were performed in infants younger than 3 months old in our institution.
Long-term survival is a tool to judge the efficacy of a treatment and the selection of patients to receive this treatment. In our unit, we found a 10-year survival of 90% after open surgical valvotomy. Alexiou and colleagues [2] reported similar results. Cowley and colleagues [10], Latiff and colleagues [11], and McCrindle and colleagues [14] have reported a long-term survival after percutaneous balloon dilatation of 72% to 83%.
One goal with open surgical commissurotomy in aortic stenosis patients in early infancy is to preserve left ventricular function. It is important to treat these patients as early as possible to prevent subendocardial ischemia and the development of endocardial fibroelastosis. In our study, all surviving patients had good left ventricular function at the latest follow-up. The group from Southampton also reported that all of their patients who survived open surgical commissurotomy were in New York Heart Association functional class I after a mean follow-up of 10 years. Patients should, nevertheless, be followed up at regular intervals to detect the development of restenosis or increasing regurgitation and to receive treatment before deterioration of the left ventricle.
The median peak systolic echo Doppler gradient reduction in our study group, 68 mm Hg, is comparable with what other studies have found. The reported reduction range is 25 to 52 mm Hg in surgically treated patients and 28 to 64 mm Hg in balloon-dilated patients [9, 13, 16–18]. We find that the gradient after open surgical commissurotomy keeps very well over time in most cases (Fig 2), in accordance with the findings of Hawkins and colleagues [5].
Previous studies have shown that the frequency of clinically significant AR after intervention for neonatal critical aortic stenosis is higher after transcatheter balloon valvotomy than after open commissurotomy [14], as supported by our findings. In a recent study, 29% of balloon-dilated critical aortic stenosis patients underwent surgical treatment for residual aortic valve dysfunction within a median time of 7 months [15]. The dominating problem was aortic stenosis in 8 patients (14%) and AR in 3 (5%). At 2 years after balloon dilatation, Balmer and colleagues [18] reported relevant AR in 50% of infants younger than 3 months old, and 65% required reoperation within 3 years. Echigo [12] reported that 14% underwent reoperation with a Ross procedure owing to AR soon after balloon valvuloplasty.
The reasons for AR have been identified to be tears, perforations, partial detachment of the cusp, or commissural avulsions [16, 19]. By a more precise opening of the commissures and less trauma to the cusps, surgical correction can provide relief of the stenosis without a high incidence of early regurgitation and need for aortic valve replacement early in life, an opinion supported by the results from the group in Southampton [17]. In centers with substantial experience with neonatal cardiac surgery, open surgical commissurotomy can be performed with low risk and is the more logical option from an anatomic point of view. The procedure allows visualizing the valve and opening the valve precisely in the commissures.
If reintervention is needed, our policy has been to do redo valvotomy if the stenosis has progressed. An invasive gradient or mean gradient at Doppler investigation of more than 50 mm Hg, ST-segment changes produced during work, and history of fatigue or central chest pain, or both, are criteria to proceed to operation. If there is progress of aortic incompetence only or in combination with valvar or subvalvar stenosis, a Ross procedure is discussed if the Doppler investigation shows a severe degree of incompetence or moderate with increasing dilation of the left ventricle. Usually, magnetic resonance imaging is performed to quantify the degree of incompetence, and a regurgitant fraction of more than 40% is considered indication for surgery. In male adolescents or adults with an annulus large enough to receive a No. 23 mechanical prosthesis, this alternative will be discussed as the first option.
In conclusion, this study agrees with other recent reports that there is some evidence for open surgical commissurotomy to be a more precise treatment of aortic valve stenosis in early infancy compared with balloon valvuloplasty and with a lower—or at least postponed—rate of reintervention.
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Acknowledgments
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We thank Dr Gudrun Björkhem, Department of Pediatric Cardiology, Lund, Sweden, for important suggestions concerning the cardiology follow-up program, and Dr Thomas Higgins for language revision.
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References
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Abstract
Introduction
