Ann Thorac Surg 2001;71:907-910
© 2001 The Society of Thoracic Surgeons
Original article: cardiovascular
Long-term results of relief of subaortic stenosis in univentricular atrioventricular connection with discordant ventriculoarterial connections
Marjan Jahangiri, FRCSa,
Elliot A. Shinebourne, FRCPa,
David B. Ross, MDb,
Robert H. Anderson, FRCPatha,
Christopher Lincoln, FRCSa
a Department of Cardiology and Cardiac Surgery, Royal Brompton Hospital, London, England, United Kingdom
b Department of Cardiac Surgery, IWK-Grace Health Center, Halifax, Nova Scotia, Canada
Accepted for publication October 18, 2000.
Address reprint requests to Dr Jahangiri, Department of Cardiac Surgery, Great Ormond Street Hospital for Children, Great Ormond St, London WC1N 3JH, England
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Abstract
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Background. We set out to examine the long-term results of relief of subaortic stenosis by enlargement of ventricular septal defect in patients with univentricular atrioventricular connection to a dominant left ventricle and discordant ventriculoarterial connections.
Methods. Twenty-four patients underwent enlargement of ventricular septal defect between 1985 and 1998 at a median age of 3.2 years (range, 3 weeks to 14 years). Ten patients were younger than 1 year of age. Eighteen had undergone previous banding of the pulmonary trunk, 9 of whom also required repair of coarctation of the aorta. The median subaortic gradient before enlargement was 46 mm Hg. Twenty-three patients had a patch to enlarge the rudimentary right ventricle.
Results. Five patients (21%) died in the early postoperative period. The overall survival at 1 and 3 years was 73%, and at 5 and 10 years was 68% and 60%, respectively. Complete heart block requiring insertion of a pacemaker occurred in 2 patients (8%). A Fontan operation was performed in 10 patients, 5 underwent a bidirectional Glenn procedure, and 2 required cardiac transplantation. Follow-up was complete in all survivors at a median time of 6.7 years (range, 8 months to 13 years). From the earlier part of the series, 3 patients experienced aortic insufficiency and 2 had recurrent obstruction. Factors adversely affecting survival were age younger than 1 year at operation and presence of obstruction within the aortic arch.
Conclusions. Our experience shows that, in patients with univentricular atrioventricular connection to a dominant left ventricle and subaortic stenosis, enlargement of the ventricular septal defect provides satisfactory relief of obstruction except in those younger than 1 year of age, and those who have associated obstruction in the aortic arch.
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Introduction
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Subaortic stenosis is well known to complicate the clinical course of patients with univentricular atrioventricular connection (double inlet, absent right or left atrioventricular connection) to a dominant left ventricle when the ventriculoarterial connections are discordant. Often the diagnosis and relief of the obstruction is delayed in neonates because it is underestimated owing to patency of the arterial duct. The obstruction usually manifests itself with time. The delay in relieving stenosis can cause ventricular hypertrophy, which is an important risk factor for the subsequent Fontan procedure that these patients will eventually require [1]. Alternative surgical options include a first-stage Norwood procedure, banding of pulmonary trunk, and subsequent relief of subaortic stenosis by a Damus-Kay-Stansel procedure or its modifications [2, 3] or a neonatal arterial switch operation [4].
In 1990, we reported the surgical technique for relief of subaortic obstruction by enlargement of the ventricular septal defect (VSD) [5], and subsequently reported the early results of this procedure [6]. Some of the concerns regarding this technique have been the risk of damage to the conduction tissue, not addressing a small aortic root if this is present, and the possible risk of formation of aneurysm after patching the outflow tract from the rudimentary ventricle. To address these issues, we have now reviewed our experience over the longer term.
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Patients and methods
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We identified a total of 24 patients with a univentricular atrioventricular connection to a dominant left ventricle and discordant ventriculoarterial connections who underwent relief of subaortic obstruction between September 1985 and December 1998. Our routine practice to relieve subaortic stenosis in this setting has been enlargement of the VSD. The precise anatomic diagnosis is shown in Table 1. Associated cardiac anomalies are shown in Table 2. Diagnosis was made in all patients by transthoracic echocardiography. In the earlier part of the study, catheterization was performed in 13 patients. The median subaortic gradient was 46 mm Hg (range, 20 to 104 mm Hg). In 2 patients, despite low gradients, the subaortic area was considered obstructive as seen by imaging.
A total of 24 palliative procedures were performed. Banding of the pulmonary trunk was performed in 9 patients at a median age of 3.3 months (range, 5 days to 18 months), and a further 9 underwent banding combined with repair of aortic coarctation at a median age of 1.8 months (range, 6 days to 2 months). A left modified Blalock-Taussig shunt was constructed in 2, and atrial septectomy was performed in 4 patients.
The subaortic stenosis was relieved at a median age of 3.2 years (range, 3 weeks to 14 years). Ten patients were younger than 1 year of age at the time of the operation. The median interval for patients who had undergone banding was 4.2 years (range, 2 weeks to 14 years).
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Results
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Five patients (21%) died in the early postoperative period (< 30 days). Of these patients, 3 were younger than 1 year of age. Sudden cardiac arrest accounted for 3 deaths, the patients not being responsive to resuscitative measures. The other 2 patients died of respiratory and renal failure. Postmortem studies did not show any residual obstruction within the outflow tract to either the left or the right ventricle. The overall survival at 1 and 3 years was 73%, and at 5 and 10 years was 68% and 60%, respectively (Fig 1).
Two (8%) patients experienced complete heart block requiring insertion of a pacemaker. Both are doing well after periods of 3 and 6 years.
Mild aortic insufficiency, found in 3 patients who underwent operation in the earlier part of the series, could have resulted from damage to the aortic valve at the time of the procedure. At that time, we did not routinely open the aorta before incising the rudimentary right ventricle and enlarging the VSD. We came to recognize that the most lower part of the anterior aortic sinus is more caudal in the outlet chamber than expected. Therefore, siting the incision in the free wall of the outlet chamber is facilitated by inspection through the aortotomy. Since we have routinely opened the aorta, paying particular attention not to damage the aortic valve, we have encountered no further incidence of aortic insufficiency. Recurrent obstruction occurred in the first 2 patients of the series, in whom enlargement of the rudimentary ventricle with a patch was not undertaken. This is now performed routinely, and there have been no further cases of recurrent obstruction.
Ten patients have received a complete Fontan operation, whereas 5 have undergone a bidirectional Glenn shunt, and 2 required cardiac transplantation. Follow-up was complete in all survivors over a median period of 6.7 years (range, 8 months to 13 years). There were 3 deaths during follow-up. One patient, with tricuspid atresia and associated coarctation, initially underwent banding and repair of coarctation. She underwent enlargement of the septal defect at the age of 18 months. Her initial postoperative recovery was uncomplicated. Follow-up showed deteriorating left ventricular function. She died 9 months after repair. The second patient died at the age of 4.6 years. Banding and balloon atrial septostomy had been performed in the neonatal period, and the septal defect was enlarged at 9 months of age. He did well, and a fenestrated total cavopulmonary connection was performed at age 4.6 years, which was complicated by persistent pleural effusions. He was diagnosed to have thrombosis of the inferior caval vein. Postmortem examination showed a widely patent subaortic region with a large interventricular communication. The third patient had a hypoplastic left pulmonary artery and associated coarctation, and underwent repair of coarctation and banding at the age of 2 days. A classic Glenn procedure was performed when he was 9 months of age. Five years later, he underwent an extracardiac Fontan operation. He died 3 days after the operation because of persistently high pressure in the pulmonary arteries and a failing ventricle.
Survival was analyzed according to age, surgical era, and presence or absence of obstruction within the aortic arch. There was no difference in survival according to the surgical era (Fig 2). Presence of an obstructed aortic arch, (Fig 3) and having the operation performed in the neonatal period (Fig 4), in contrast, significantly reduced survival (p = 0.01 and p = 0.05, respectively) .
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Fig 4. Kaplan-Meier estimated survival according to whether operation was performed in the neonatal period or after 1 year of age.
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A recent echocardiogram was performed in all patients, and the right ventricular patch was examined for evidence of aneurysmal transformation. This was not detected in any of the patients.
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Comment
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The surgical management of a restrictive interventricular communication still remains a challenge in patients with big left and small right ventricles. In the earlier part of our experience [5, 6], relief of obstruction was performed mainly in patients who had undergone banding of the pulmonary trunk, which could have exacerbated the subaortic obstruction [1]. In the remainder, enlargement of the VSD was performed without any other preliminary palliative procedure. Banding in this group of patients has been condemned by some, who believe that the resulting ventricular hypertrophy, and the possible decrease in compliance, can jeopardize the success of a future Fontan procedure. In our cohort, of the 18 patients who had undergone banding, 8 have successfully been converted to the Fontan circulation. All of these patients are well at follow-up. It may be that the risk of ventricular hypertrophy subsequent to pulmonary arterial banding is more theoretical than real.
Others avoided enlarging the septal defect for fear of producing heart block. This can be avoided with proper knowledge of the location of the atrioventricular conduction axis [5]. Despite this knowledge, however, 2 of our patients have required insertion of pacemakers. The 3 patients who died suddenly in the early postoperative period could also have suffered arrhythmic events.
We did not find aneurysmal transformation of the right ventricular patch in any of the patients. Our experience shows that it is advantageous to use a patch to close the right ventriculotomy to avoid subsequent restriction of the right ventricular outflow tract.
An alternative to the enlargement of VSD in this complex congenital heart disease has been the Damus-Kay-Stansel procedure. The earlier results, however, have been disappointing. The problem seems to have been balancing properly the flow in the systemic and pulmonary circuits. With growing experience from the management of patients with hypoplastic left heart syndrome, this may no longer be the case. Others have reported their experience with this complex problem using modifications of the Damus-type procedure. Brawn and colleagues [2] have reported 37.5% mortality in the short term, whereas others using a different modification of the Damus procedure encountered no early mortality [3, 7].
Our experience shows that enlargement of the VSD can provide satisfactory relief over the longer term with univentricular atrioventricular connection to a dominant left ventricle and subaortic stenosis. However, those patients younger than 1 year of age who have obstruction of the aortic arch are likely to fare better with a Norwood procedure or a modification of the Damus operation.
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References
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Brawn W.J., Sethia B., Jagtap R., et al. Univentricular heart with systemic outflow obstruction: palliation by primary Damus procedure. Ann Thorac Surg 1995;59:1441-1447.[Abstract/Free Full Text]
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Abstract
Introduction
