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Ann Thorac Surg 1999;68:1723-1726
© 1999 The Society of Thoracic Surgeons

Original Articles

Left ventricular outflow tract obstruction after partial atrioventricular septal defect repair

A. Tayfun Gurbuz, MDa, William M. Novick, MDa, Connie A. Pierce, RNa, Donald C. Watson, MDa

a Department of Cardiovascular Surgery, University of Tennessee, Le Bonheur Children’s Medical Center, Memphis, Tennessee, USA

Address reprint requests to Dr Novick, The Heart Center, 777 Washington Ave, Suite P215, Memphis, TN 38103
e-mail: ichfno{at}aol.com

Presented at the Forty-fifth Annual Meeting of the Southern Thoracic Surgical Association, Orlando, FL, Nov 12–14, 1998.


   Abstract
Top
 Abstract
Introduction
 Patients and methods
 Results
 Comment
 References
 
Background. Narrowing of the left ventricular outflow tract has been associated with partial atrioventricular septal defect (PAVSD) in about 3% of patients. Because of the predisposing anatomy, hemodynamically significant obstruction in the subaortic area may appear after repair of ostium primum atrial septal defects.

Methods. From 1984 to 1998, 40 patients underwent surgical correction of PAVSD by patch closure. The mean age at the initial repair was 5.8 years (range 3 months to 22 years).

Results. Nine patients had 12 subsequent operations for hemodynamically significant subaortic obstruction. The mean age at PAVSD repair was 17 months (3 to 42 months) (p < 0.001 compared with others). Follow-up work-up was obtained due to symptoms in 5 patients and an abnormal echocardiogram in 4 asymptomatic patients. Subaortic stenosis developed at a mean of 5 years (range 4 months to 10 years), and 6 or more years in 4 patients. The mean age at subaortic stenosis repair was 6 years (range 2 to 12 years). Nine patients underwent subaortic fibromuscular resection. Of these, 4 developed recurrent stenosis and 2 have undergone additional operations.

Conclusions. Left ventricular outflow tract obstruction after PAVSD repair may be more frequent than reported. Because of the progressive nature of the process, echocardiography should be utilized liberally on patients to uncover subclinical stenosis. Long-term follow-up is essential for diagnosis due to delayed appearance and lack of reliable clinical signs.


   Introduction
Top
 Abstract
 Introduction
Patients and methods
 Results
 Comment
 References
 
Left ventricular outflow tract obstruction (LVOTO) after repair of partial atrioventricular septal defect (PAVSD) has been recognized since the early 1980s [1, 2]. Inherent narrowing of the left ventricular outflow tract (LVOT) and the associated anomalies involving the mitral valve potentiate the development of LVOTO in repaired patients. Subaortic obstruction can remain clinically silent for many years and is often not recognized [1]. The development of subaortic stenosis is usually progressive, may result in significant complications, and may be more common than the reported 3% to 4% incidence [1, 2]. The incidence and clinical course of subaortic stenosis after PAVSD repair is often reported with complete atrioventricular (AV) septal defects [3] or included under the general heading of "subaortic stenosis" [4]. This report is a review of our experience with LVOTO developing after repair of PAVSD.


   Patients and methods
Top
 Abstract
 Introduction
 Patients and methods
Results
 Comment
 References
 
All patients with the diagnosis of AV septal defect that were treated between 1984 and 1998 at the authors’ institution were reviewed from a database. Complete AV septal defects were excluded. Patients with AV septal defects having two separate AV valve orifices and those with the diagnosis of primum atrial septal defect (ASD) were included in the study. Medical records, catheterization reports, cineangiograms, echocardiography tapes, and operative summaries were reviewed. Also, all patients with the diagnosis of subaortic obstruction were identified, and patients with previous PAVSD repairs were included in the study. Clinical and echocardiographic follow-up included cardiology clinic visits, review of the most recent echocardiographic reports, and telephone conversations with the patient’s family and/or physician. Follow-up was completed during May 1998.

Forty patients (18 male and 22 female) comprise the study group. No perioperative mortality occurred. Mean age at the repair of PAVSD was 5.8 years (range 6 months to 22 years). Nine patients had trisomy 21. Repair was performed under 1 year of age in 9 patients. Symptoms of various degrees of congestive heart failure were present in 28 patients (70%) before repair. These patients were being treated with at least one medication. Cardiac catheterization on 21 patients revealed no LVOT gradients. All patients had separate AV valve orifices and a large ostium primum ASD. Associated congenital cardiac abnormalities were present in 13 patients (Table 1). A cleft was present in the anterior leaflet of the left AV valve in all patients. Mitral valve regurgitation was demonstrated in 14 patients (mild in 6, moderate in 6, and severe in 2). Every effort was made to achieve a competent left AV valve at the end of repair. Closure of the mitral valve cleft was performed in all patients before 1990 and a selective approach was used after 1990 (Table 2). Clinical and echocardiographic follow-up was performed in 39 patients with a mean interval of 7.4 years (range 1 to 14 years).


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  		Table 1. Associated Cardiac Defects

 

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  		Table 2. Operative Characteristics

 

   Results
Top
 Abstract
 Introduction
 Patients and methods
 Results
Comment
 References
 
Nine patients were subsequently treated for significant subaortic obstruction. Three patients had their initial operations in other centers. There were 5 males and 4 females, with an average age of 17 ± 11 months (mean ± SD) at the time of PAVSD repair (p < 0.001 compared with ages of those without subsequent LVOTO). Subaortic stenosis was diagnosed 61 ± 32 months after repair of the PAVSD. All 9 patients had patch closure of primum ASD and 7 had closure of the mitral valve cleft (p = NS versus those without subaortic stenosis who underwent cleft closure). Mild dyspnea on exertion in 3 patients and chest pain with exercise in 2 patients caused evaluation. Subaortic stenosis was uncovered during a routine follow-up in 4 patients. LVOT gradients were determined by echocardiographic peak-to-peak velocity in 3 and left ventricle-to-aorta pull-back pressures in 6 patients. The average gradient across the LVOT was 78 ± 24 mm Hg. No aortic valvular insufficiency was seen. Twelve operations to relieve subaortic obstruction have been performed in this group. All but two procedures were performed at the authors’ institution. Subaortic fibromuscular tissue was resected through an aortotomy as an initial procedure in all patients. In 2 patients, mitral valve attachments were thought to contribute to the LVOTO and accessory chordae were divided (1 patient) and anomalous fibrous attachments of the mitral valve (1 patient) were divided. Additional procedures were mitral valve annuloplasty (1 patient) and aortic valve commissurotomy (1 patient). The mean echocardiographic gradient across the LVOT was 18 ± 4 mm Hg 1 month postoperatively. No patient died. These patients were followed for a mean of 6.3 ± 4 years after subaortic resection. Four patients developed recurrent obstruction of the LVOT after a mean of 5.5 ± 2.5 years. The mean gradient across the LVOT tract was 74 ± 23 mm Hg. One patient failed to adhere to surgical advice and died from complications of severe myocardial failure before surgery for recurrent subaortic obstruction. Two patients (22%) had reoperations for recurrent subaortic stenosis after a mean interval of 3.5 years (2 and 5 years). Both underwent resection of the infundibular septum and patch enlargement of the LVOT (modified Konno-Rastan procedure). The mean echocardiographic gradient across the LVOT in these 2 patients was 16 ± 2 mm Hg 1 month postoperatively. One patient is awaiting reoperation.

Data analysis
Data analysis of age and mitral cleft closure associated with the subsequent development of LVOTO was performed using the Student’s t test.


   Comment
Top
 Abstract
 Introduction
 Patients and methods
 Results
 Comment
References
 
The incidence of clinically significant subaortic obstruction after PAVSD repair has been reported to be between 3% [5] and 4% [2]. Previous reports have not separated the partial from the complete variety [6] or lack a denominator for the PAVSD [3, 7, 8]. Some have confirmed the low incidence of LVOTO after PAVSD repair in studies with follow-up as long as 20 years [6, 9, 10]. The incidence of subaortic stenosis that required operation in the present report was 15% (6 of the 40 patients). Our data indicate that this entity may occur more commonly than previously reported.

The association of closure of mitral valve cleft and the development of subaortic stenosis has been mentioned by some authors [11]. Mobility of the valve is decreased considerably by closing the cleft where the leaflets are tethered to the ventricular septum. This limits the normal systolic displacement of the valve leaflets away from the septum and can precipitate obstruction in the already narrowed subaortic area. The first clinical report of this was by Levy and associates [11], who attributed the two early deaths in their series of 55 patients with PAVSD to closure of the cleft of the left AV valve with resultant LVOTO and left ventricular failure. The only long-term follow up was by Najm and associates [12], who reported a 90% freedom from subaortic obstruction 14 years after AV septal repair in 180 patients. The mitral valve cleft was closed completely in 59% and partially in 29% of the patients. All patients had mitral valve cleft closure before 1990 in our series. Of these 19 patients, 2 developed significant subaortic obstruction (10%). After 1990, 12 of the 21 patients (57%) had mitral valve cleft closure. Of these 21, 4 patients (19%) developed subaortic obstruction. We agree closure of the mitral valve cleft does narrow the LVOT. However, we did not find that closing the mitral valve cleft resulted in an increase in thefrequency of subaortic obstruction in our series. The association of young age at the time of initial repair and the development of subaortic obstruction reported by Manning and associates [13] is similar to our experience. Eight of the 9 patients that developed subaortic stenosis were less than 2 years of age (4 patients less than 1 year of age) in our series.

The development of subaortic obstruction is asymptomatic in 60% to 70% of patients [14, 15]. The symptoms were mild or absent in 7 of the 9 patients in this report (77%). The mean interval to the development of subaortic obstruction after repair of PAVSD is variable but is described in the range of 68 months [16] to 81 months [17]. This is comparable with the interval in this series (61 months). This relatively long interval warrants continued long-term echocardiographic follow-up.

A spectrum of surgical approaches has been described for treatment of subaortic stenosis. Resection of the subaortic membrane through an aortotomy represents the initial procedure in most series [3, 18]. Although it is safe and provides good early results with decreased LVOT gradients after surgery, this procedure is associated with a high incidence of recurrence in the range of 5% to 36% in the series where all causes were grouped together [14, 16]. In the series by Van Arsdell and associates, who looked at only patients with AV canal defects, the incidence of recurrence was 37% [3]. Reoperation was recommended to 44% of the patients in our series. We agree with Roughneen and associates [4] that in patients with recurrent stenosis there is a high likelihood that the outflow septum is hypoplastic and enlargement of this area with a modified Konno procedure, as described by Cooley and associates [19], is necessary.

Additional abnormalities of the left AV valve can contribute to the LVOTO in some patients with AV septal defect [3, 8, 20]. Left AV valve malformations with subaortic obstruction has led some to perform mitral valvuloplasty in addition to fibromuscular resection [21]. Van Son and associates [21] described detaching both the superior and inferior, bridging leaflets from the crest of the ventricular septum to convert a PAVSD to a complete AV septal defect. Resuspension of the annuli of the AV valves from the VSD patch is used to close the newly formed interventricular communication. We agree with Van Arsdell and associates [22] that these procedures should be reserved for patients with recurrent subaortic obstruction who have proven LVOTO due to abnormalities of the left AV valve complex.

The risk of developing subaortic obstruction after repair of the PAVSD is real and probably underestimated. Difficulties in the long-term follow-up in the pediatric patient population may result in delay in the diagnosis and treatment. Postoperative apical systolic murmurs should warrant thorough investigation and not be attributed to residual mitral insufficiency. There should be a low threshold for echocardiography in patients after repair of a PAVSD to uncover a subclinical subaortic obstruction.


   References
Top
 Abstract
 Introduction
 Patients and methods
 Results
 Comment
 References
 

  1. Taylor N.C., Somerville J. Fixed subaortic stenosis after repair of ostium primum defects. Br Heart J 1981;45:689-697.[Abstract/Free Full Text]
  2. Ebels T., Meijboom E.J., Anderson R.H., et al. Anatomic and functional "obstruction" of the outflow tract in atrioventricular septal defects with separate valve orifices (ostium primum atrial septal defect). Am J Cardiol 1984;54:843-847.[Medline]
  3. Van Arsdell G.S., Williams W.G., Boutin C., et al. Subaortic stenosis in the spectrum of atrioventricular septal defects. Solutions may be complex and palliative. J Thorac Cardiovasc Surg 1995;110:1534-1542.[Abstract/Free Full Text]
  4. Roughneen P.T., DeLeon S.Y., Cetta F., et al. Modified Konno-Rastan procedure for subaortic stenosis. Ann Thorac Surg 1998;65:1368-1376.[Abstract/Free Full Text]
  5. Somerville J. Atrioventricular defects. In: Goodman M., ed. Paediatric cardiology. London: Churchill Livingstone, 1980:257-264.
  6. De Biase L., Di Ciommo V., Ballerini L., Bevilacqua M., Marcelletti C., Marino B. Prevalence of left-sided obstructive lesions with atrioventricular canal without Down’s syndrome. J Thorac Cardiovasc Surg 1986;91:467-472.[Abstract]
  7. Lappen R.S., Muster A.J., Idriss F.S., et al. Masked subaortic stenosis in ostium primum atrial septal defect. Am J Cardiol 1983;52:336-340.[Medline]
  8. Sellers R.D., Lillehei C.W., Edwards J.E. Subaortic stenosis caused by anomalies of the atrioventricular valves. J Thorac Cardiovasc Surg 1964;48:289-302.
  9. Wright J.S., Newman D.C. Complete and intermediate atrioventricular canal in infants less than a year old. Ann Thorac Surg 1982;33:171-173.[Medline]
  10. Portman M.A., Beder S.D., Ankeney J.L., van Heeckeren D., Liebman J., Riemenschneider T.A. A 20 year review of ostium primum defect repair in children. Am Heart J 1985;110:1054-1058.[Medline]
  11. Levy M.J., Cuello L., Tuna N., et al. Atrioventricularis communis. Am J Cardiol 1964;14:587-598.
  12. Najm H.K., Williams W.G., Churatanaphong S., Watzka S., Freedom R.M. Primum atrial septal defect in children. Ann Thorac Surg 1998;66:829-835.[Abstract/Free Full Text]
  13. Manning P.B., Mayer J.E., Sanders S.P., et al. Unique features and prognosis of primum ASD presenting in the first year of life. Circulation 1994;90(pt 2):30-35.
  14. Douville E.C., Sade R.M., Crawford F.A., Wiles H.B. Subvalvar aortic stenosis. Ann Thorac Surg 1990;50:29-34.[Abstract]
  15. Jacobs J.P., Palatianos G.M., Cintron J.R., Kaiser G.A. Transaortic resection of the subaortic membrane. Chest 1994;106:46-51.[Abstract/Free Full Text]
  16. Lupinetti F.M., Pridjian A.K., Callow L.B., Crowley D.C., Beekman R.H., Bove E.L. Optimum treatment of discrete subaortic stenosis. Ann Thorac Surg 1992;54:467-471.[Abstract]
  17. Reeder G.S., Danielson G.K., Seward J.B., Driscoll D.J., Tajik A.J. Fixed subaortic stenosis in atrioventricular canal defect. J Am Coll Cardiol 1992;20:386-394.[Abstract]
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  19. Cooley D.A., Garrett J.R. Septoplasty for left ventricular outflow tract obstruction without aortic valve replacement. Ann Thorac Surg 1986;42:445-448.[Abstract]
  20. Piccoli G.P., Ho Sy, Wilkinson J.L., MacCartney F.J., Gerlis L.M., Anderson R.H. Left sided obstructive lesions in atrioventricular septal defects. An anatomic study. J Thorac Cardiovasc Surg 1982;83:453-460.[Abstract]
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