Scimitar SyndromeClinical Perspective
A European Congenital Heart Surgeons Association (ECHSA) Multicentric Study
Background—Scimitar syndrome is a rare congenital heart disease. To evaluate the surgical results, we embarked on the European Congenital Heart Surgeons Association (ECHSA) multicentric study.
Methods and Results—From January 1997 to December 2007, we collected data on 68 patients who underwent surgery for scimitar syndrome. Primary outcomes included hospital mortality and the efficacy of repair at follow-up. Median age at surgery was 1.4 years (interquartile range, 0.46 to 7.92 years). Forty-four patients (64%) presented with symptoms. Surgical repair included intraatrial baffle in 38 patients (56%; group 1) and reimplantation of the scimitar vein onto the left atrium in 21 patients (31%; group 2). Eight patients underwent right pneumectomy, and 1 had a right lower lobe lobectomy (group 3). Four patients died in hospital (5.9%; 1 patient in group 1, 2.6%; 3 patients in group 3, 33%). Median follow-up time was 4.5 years. There were 2 late deaths (3.1%) resulting from severe pulmonary arterial hypertension. Freedom from scimitar drainage stenosis at 13 years was 83.8% in group 1 and 85.8% in group 2. Four patients in group 1 were reoperated, and 3 patients (2 in group 1 [6%] and 1 in group 2 [4.8%]) required balloon dilation/stenting for scimitar drainage stenosis.
Conclusions—The surgical treatment of this rare syndrome is safe and effective. The majority of patients were asymptomatic at the follow-up control. There were a relatively high incidence of residual scimitar drainage stenosis that is similar between the 2 reported corrective surgical techniques used.
Scimitar syndrome is a rare association of congenital cardiopulmonary anomalies that has been reported in 3% to 6% of patients with partial anomalous venous connection. In these patients, some of the pulmonary veins drain into the upper part of the inferior vena cava,1,–,6 either above or below the diaphragm,7 and usually drain the lower and sometimes the middle lobe of the right lung (79%) or the whole right lung (21%).1 The right lung is frequently hypoplastic and receives its blood supply from the systemic arteries, mainly the thoracic or abdominal aorta, and this supply is usually to the lower lobes.8
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About 70% of these patients with scimitar syndrome have an associated atrial septal defect.9 The syndrome also has been described less commonly in association with other cardiac malformations like tetralogy of Fallot,10,11 ventricular septal defect,7,–,9,12,–,15 coarctation of the aorta,3,14,16 hypoplastic left heart syndrome,5 total anomalous pulmonary venous connection,16 patent ductus arteriosus,3,10,13,–,18 cor triatriatum,19 bicuspid aortic valve,10,15 and subaortic stenosis.16 Overall, 19% to 31% of patients with scimitar syndrome have associated cardiac anomalies.1,10,11,15,20
This syndrome can present early in the neonatal period or later in life with a wide clinical spectrum.4,14,16,21 Dupuis et al19 divided scimitar syndrome into 3 main forms: an infantile form with symptoms and pulmonary hypertension, an “older” adult form distinguished by being asymptomatic in infancy, and a form with associated congenital cardiac anomalies.
Surgical correction is usually accomplished in symptomatic patients or in patients with an increased pulmonary blood flow and signs of right heart chamber dilation.4,13 Several different surgical approaches have been described over the years and are currently used, depending on the anatomic and pathological features of each case and according to the surgeon's preference.15,19,–,28
The objective of this study was to analyze the surgical results and follow-up outcome of patients who underwent surgery for scimitar syndrome within a European Congenital Heart Surgeons Association (ECHSA) multicentric data collection in a relatively recent time period. To the best of our knowledge, this is the widest surgical experience collected so far in the medical literature.
A review of the medical records and computerized hospital data was approved by the Clinical Investigation Committee of the University Hospital of Padua, and the procedures followed were in accordance to the institutional guidelines for retrospective record review and protection of patient confidentiality. Individual consent was not obtained by patients enrolled in this study. Patients were not identified, and the chairperson of the Ethics Committee of each institution consented to send data from that institution for publication.
The data reviewed were relative to the hospital course and to the follow-up clinical controls of patients with scimitar syndrome who required surgical treatment between January 1997 and December 2007. Nineteen of the 42 cardiothoracic centers within the ECHSA contributed to the data collection.
Variables analyzed included demographic and preoperative clinical data, different operative techniques (group 1, patients who had an intraatrial baffle repair; group 2, patients who had a reimplantation of the scimitar vein on the left atrium; and group 3, patients who underwent right pneumectomy or right lung lobectomy).
Primary outcomes included hospital mortality and morbidity rates, late mortality, and scimitar drainage patency at the last follow-up control. The presence of pulmonary arterial hypertension was defined as a mean pulmonary artery pressure >25 mm Hg at rest or >30 mm Hg with exercise.29
Quantitative variables were summarized as median and interquartile range (IQR), equal to the difference between the third (75% of the distribution) and first (25% of the distribution) quartiles. Because quantitative variables are not normally distributed, comparisons among groups were carried out by the Kruskal-Wallis test.30 When 2 groups were compared, the Wilcoxon signed-rank test was used. The difference between proportions was assessed by the extension of the Fisher exact test proposed by Freeman and Halton31 for comparisons among >2 proportions. Data were analyzed with SAS software, release 9.1.3 (SAS Stat 9.1, SAS Institute Inc, Cary, NC), and values of P<0.05 were considered significant.
Sixty-eight consecutive patients who underwent surgical treatment for scimitar syndrome within 19 ECHSA centers were included in this study. Each center entered between 1 and 9 patients (median, 3 patients per center) in this study. There were 43 female patients (63%) and 25 male patients (37%). Preoperative diagnosis was established by echocardiography in all patients. Additional instrumental examinations included cardiac catheterization in 57 patients (84%) and MRI in 5 patients (7.3%). Forty-four patients (64%) presented with symptoms that included recurrent upper respiratory tract infections (n=27 patients), congestive heart failure (n=24), recurrent pneumonia (n=9 patients), and cyanosis (n=4 patients). The presence of congestive heart failure was significantly higher in patients <3 months of age compared with older patients (P=0.02). In a 46-day-old male patient scheduled for ventricular septal defect closure, an association of an anomalous right pulmonary venous drainage with the inferior vena cava was discovered accidentally at the time of repair.
Associated cardiac anomalies were present in 51 patients (75%). The most common included atrial septal defect secundum type (atrial septal defect II) in 44 patients (65%), ventricular septal defect in 11 (16%), and patency of the ductus arteriosus in 6 (9%). Nineteen of 68 patients (28%) presented with associated congenital heart disease, excluding patency of the ductus arteriosus and atrial septal defects. Right lung hypoplasia was described in 35 patients (52%).
Fifty-seven patients (84%) who underwent preoperative cardiac catheterization showed a median systolic pulmonary artery pressure of 30 mm Hg (IQR, 24 to 35 mm Hg). Thirteen patients (22%) presented with pulmonary arterial hypertension, which was reported more frequently in patients with other associated congenital heart defect. Median ratio of pulmonary blood flow to systemic blood flow was 2:1 (IQR, 1.8:1 to 3:1). Systemic arterial supply to the right lung was demonstrated in 20 patients (29%); 6 were treated by coil embolization of aortopulmonary collaterals at the time of preoperative study. All 6 patients presented with congestive heart failure (P=0.001). Pulmonary sequestration was reported in 6 patients (8.8%) (Table 1).
Surgical repair included intraatrial baffle repair in 38 patients (56%; group 1) and reimplantation of the scimitar vein on the left atrium in 21 patients (31%; group 2). Six patients who underwent surgical repair (3 in group 1 and 3 in group 2) underwent a simultaneous ligation of collateral arteries supplying the right lung. The remaining 9 patients underwent a right pneumectomy (8 patients) or a right lower lobe resection (1 patient; group 3). One patient in group 3 underwent a previous atrial septal defect closure followed by a right lung pneumectomy during the same hospitalization.
Median age at surgery was 1.4 years (IQR, 0.46 to 7.92 years). Thirty-one patients (45%) were <12 months of age, and 54 of 68 patients (79%) underwent surgery within the first decade of life. Surgical approach was through a midline sternotomy in 52 patients (76%) and a right thoracotomy in 16 patients (24%; 3 patients in group 1, 6 patients in group 2, and 7 patients in group 3). Patients in group 3 were significantly younger than patients in groups 1 and 2 (P=0.05; Tables 2 and 3). Associated surgical maneuvers were reported in 51 patients (75%) and are listed in Table 4.
Median time in the intensive care unit and hospitalization time are reported in Tables 1 and 2. Postoperative complications were reported in 35 patients (51%; Table 5), being more frequent in group 3 (7 of 9, 78%; P=0.02) compared with group 2 (14 of 21, 67%) and group 1 (14 of 38, 37%) and essentially related to the presence of preoperative congestive heart failure (odds ratio=13, P=0.004; Tables 1 and 2). Patients who had postoperative complications were younger (median age, 0.59 years; IQR, 0.33 to 2.37 years) compared with uncomplicated patients (median age at surgery, 5.6 years; IQR, 0.9 to 12 years; P=0.003, Wilcoxon signed-rank test).
Patients in group 2 showed a significantly higher incidence of postoperative arrhythmias (P=0.002, extended Fisher exact test) and phrenic nerve injury (P=0.04, extended Fisher exact test). Patients in group 3 had a significantly higher incidence of prolonged intubation (>7 days; P=0.01, extended Fisher exact test) and postoperative pneumonia (P=0.001, extended Fisher exact test).
Four patients (5.9%) died in hospital: 1 of severe brain injury 56 days after an initial intraatrial baffle repair (group 1, 2.6%) and 3 in group 3 (33%; P=0.008) 15, 35, and 157 days after right pneumectomy for neurological problems, pulmonary hypertensive crises, and sepsis, respectively. Hospital mortality was significantly higher in patients with pulmonary arterial hypertension (P=0.03; Figure 1). All patients who died in hospital were found to have preoperative congestive heart failure and severe respiratory symptoms.
All patients who underwent a primary right lung pneumectomy had severe right lung hypoplasia, and their scimitar vein drained the entire right lung (Table 1). Five of 9 patients had preoperative congestive heart failure (56%), and 5 patients (56%) had severe respiratory symptoms. In addition, the majority of patients presented with a severe degree of pulmonary arterial hypertension at the catheterization study (5 of 9, 56%; P=0.003).
Median follow-up time was 4.5 years (IQR, 1.6 to 8.3 years), which was completed in 63 of the 64 survivors (98.5%). One patient who underwent right pneumectomy was lost to follow-up.
There were 2 late deaths (3.1%), both resulting from right ventricular failure caused by severe pulmonary arterial hypertension (1 in group 1, 2%; 1 in group 2, 4%; P=0.58) 8 years and 126 days after surgery, respectively (Figure 1). A lung biopsy obtained in the patient in group 2 at the time of scimitar vein reimplantation, ventricular septal defect closure, and patency of the ductus arteriosus ligation showed Heath-Edwards class III pulmonary vascular obstructive disease.
At the last clinical follow-up control, 52 of 61 patients (85.2%) were in New York Heart Association class I. Among the 9 remaining patients, all in New York Heart Association class II, symptoms were consistent with persistent dyspnea and recurrent respiratory infection.
Outcomes according to the Dupuis classification19 of scimitar syndrome are listed in Table 6. After corrective procedures, 9 patients (15.5%) showed some degree of stenosis of the scimitar drainage anastomosis at the last follow-up control, which was confirmed by angiography in all patients (6 of 37 in group 1, 16.2%; 3 of 21 in group 2, 14.2%; Figure 2). The presence of a scimitar drainage stenosis was correlated with younger age at repair (<3 months of age) only in patients in group 2 (P=0.07).
Four patients (7%), all in group 1, underwent reoperation (consisting of repositioning of the intraatrial baffle) and survived; symptoms (dyspnea and fatigue) were still present in 1 patient. Three patients (5.3%) underwent balloon dilation at the level of the stenotic connection (plus stent implantation in one of them) 8, 12, and 15 months after correction, respectively (2 in group 1, 6%; 1 in group 2, 4.8%). One patient (group 1) is still symptomatic for recurrent respiratory tract infections.
Three patients with instrumental diagnosis of scimitar drainage stenosis (1 patient in group 1 and 2 patients in group 2) are completely asymptomatic. So far, they have not been treated.
At multivariate analysis (logistic regression), no variables were significantly associated with outcomes.
Scimitar syndrome is a rare congenital heart disease characterized by a wide spectrum of symptoms depending mainly on the presence of other associated congenital heart malformations, the amount of blood draining into the inferior vena cava, the presence of scimitar vein obstruction, the degree of the arterial supply to the right lung or its lower lobe, and the presence of the bronchial abnormalities responsible for retained secretions, lobar infections, and hemoptisis.2,4,5,7,10,15,20
Because of the wide range of symptoms at clinical onset, the diagnosis may be difficult, especially in children and young adults with concomitant congenital heart lesions.2,–,5,32,33 Pulmonary artery hypertension often occurs and is seen mostly in infants12,14,16,–,18,20 with associated congenital heart malformations or with an anomalous large systemic arterial supply.11,34,–,37 However, it has also been reported in adult patients.38 A less common cause of pulmonary arterial hypertension is the presence of pulmonary vein stenosis.16,17,20
If the presence of a large systemic anomalous arterial supply to the right lung with pulmonary overcirculation is detected preoperatively, it should be abolished by occluding the systemic arteries that supply the affected lobe(s), thereby reducing the blood flow and the amount of shunting.15,16,20,32,–,34,37,–,40 This has been advocated as the best and simplest treatment, especially in infants with congestive heart failure, often improving the clinical symptoms and decreasing the pulmonary arterial pressure.1,14,17,–,19
The surgical repair of scimitar syndrome consists of redirecting the pulmonary venous drainage into the left atrium,14,15 either baffling the anomalous drainage into the left atrium via a tunnel or transecting the “scimitar drainage” near its entrance into the inferior vena cava and then reimplanting it directly into the left atrium.24 Both baffle repair and direct reimplantation of the scimitar vein have been reported for many years and are currently used according to surgeon preference and to the anatomic and pathological features of each case.22,–,28 Still, there is no consensus as to which is the best surgical treatment option.
Although repair of the anomalous venous return and ligation of collaterals is generally recommended, Huddleston et al14 reported that in symptomatic patients with repeated pulmonary infections and hemorrhage, a right lung lobectomy or pneumonectomy (either as primary therapy or if postoperative stenosis is present after failed repair) is an option leading to similar results.
In general, right lung pneumectomy is well tolerated in children,41,42 particularly in patients in whom the affected lung is hypoplastic. Lobectomy can be done only if the anomalous vein drains only that lobe, and care needs to be taken to ensure that the remaining lung function will remain adequate.
In our multicentric ECHSA study, we report on a relatively large experience with the aim of analyzing the different surgical strategies, surgical outcomes, risks, and midterm results at follow-up. Our data indicate that the scimitar syndrome is not a simple and benign congenital heart disease and that it is often associated with other cardiac anomalies that play an important role in the long-term results.
The majority of our patients presented with preoperative symptoms that represent one of the main indications for surgical repair, particularly when pulmonary arterial hypertension is present. Almost all patients with severe associated anomalies presented within the first decade of life with symptoms that are difficult to ascribe to the anomalous scimitar vein drainage, the presence of associated anomalies, or both.
Patients who underwent right pneumectomy were significantly younger compared with patients who had corrective surgery, also showing a more severe degree of preoperative respiratory symptoms and congestive heart failure. In addition, the majority of patients presented with a severe degree of pulmonary arterial hypertension at the catheterization study. These data were consistent with the higher incidence of postoperative mortality and morbidity, confirming the experience in previous studies.1,15,41,42
The analysis of our data demonstrated that corrective surgery can be done safely with a low mortality and morbidity rate, which are independent of the type of corrective surgical technique used. Of note, the presence of pulmonary arterial hypertension is associated with a higher mortality rate. Also notable is the fact that the direct reimplantation technique is linked to a higher incidence of postoperative complications and a longer hospital stay.
The great majority of our patients showed good clinical conditions at the last clinical follow-up. The overall freedom from scimitar vein stenosis was 84.5% at 10 years and was similar between patients who had a reimplantation of the scimitar vein and patients who underwent an intracardiac baffle repair (85.8% versus 83.8%). It is of note that a residual stenosis at the scimitar vein level was correlated with younger age at repair (<3 months of age) only in patients in group 2.
We have found that the results of surgical treatment are linked to patient age. As a general rule, patients <1 year of age who require treatment are usually very ill, bearing a relatively high operative mortality and complication rate, whereas those who are older have a better outcome both immediately and in the long term. Previous reports have shown that delayed surgical treatment, especially in infants with associated congenital heart lesions, can lead to irreversible pulmonary vascular obstructive disease, which can jeopardize the surgical outcome of these patients.2,5,11,13,17
Our study has some limitations. Postoperative right lung assessment by pulmonary scintigraphy was performed in only a few patients in our cohort; therefore, it is impossible to draw any conclusions about the right lung anatomy and functional status and therefore patients' clinical conditions. We believe that such a test should be performed routinely in all patients after scimitar syndrome repair to achieve an appropriate long-term follow-up.
We are aware that this study design does not allow us to reach strong conclusions about the optimal procedure for this disease. However, we have collected a complete series of data on a large series of patients who were been treated surgically in the context of a rare congenital heart malformation with many anatomic variants and different surgical option strategies.
Our multicentric ECHSA study highlights the efficacy and safety of the surgical treatment of this rare syndrome. The majority of patients were asymptomatic at the latest clinical follow-up. However, we found a relatively high incidence of residual scimitar drainage stenosis requiring reoperation or hemodynamic reintervention, which is similar in the 2 reported surgical techniques.
- Received November 25, 2009.
- Accepted June 28, 2010.
- © 2010 American Heart Association, Inc.
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Scimitar syndrome is a rare association of congenital cardiopulmonary anomalies that has been reported in 3% to 6% of patients with partial anomalous venous connection. To analyze the surgical results and follow-up outcome of patients who underwent surgery for scimitar syndrome, we embarked on an European Congenital Heart Surgeons Association (ECHSA) multicentric data collection in a relatively recent time period. Our data indicate that scimitar syndrome is not a simple and benign congenital heart disease and that it is often associated with other cardiac anomalies that play an important role in the long-term results. The majority of our patients presented with preoperative symptoms that represent one of the main indications for surgical repair, particularly when pulmonary arterial hypertension is present. We demonstrated that corrective surgery can be done safely with a low mortality and morbidity rate, which are independent of the type of corrective surgical technique used. Patients who underwent a right pneumectomy had severe right lung hypoplasia and showed a more severe degree of preoperative respiratory symptoms, congestive heart failure, and pulmonary arterial hypertension, which was also consistent with their higher incidence of postoperative mortality and morbidity. Of note also is the fact that the presence of pulmonary arterial hypertension is associated with a higher mortality rate. At the latest clinical control, the majority of patients were asymptomatic; however, we found a relatively high incidence of residual scimitar drainage stenosis (15.5%) requiring reoperation or hemodynamic reintervention, which is similar in the 2 reported surgical techniques.