Original ArticleOutcomes of Subaortic Obstruction Resection in Children
Introduction
Discrete subaortic stenosis (SAS) is an often progressive disease due to membranous or fibromuscular obstruction in the left ventricular outflow tract (LVOT). Subaortic stenosis accounts for 8-30% of LVOT obstruction in children [1], [2], [3], [4]. If untreated, severe SAS has a high morbidity and mortality [5], [6]. Subaortic stenosis may also cause aortic insufficiency (AI) through turbulent blood flow resulting in scarring and prolapse of the valve, or alternatively, direct extension of subaortic tissue onto the valve. Although surgical repair of SAS has excellent short-term outcomes, it is associated with an up to 8% chance of an iatrogenic ventricular septal defect (VSD) [7], [8], up to 14% chance of complete atrioventricular (AV) block [8], [9], and a recurrence rate of 5-27% [1], [2], [3], [9], [10].
Subaortic stenosis is commonly found in conjunction with other cardiac abnormalities, such as ventricular septal defects (VSDs) and aortic arch abnormalities. The majority of studies on surgical outcomes of SAS are mixed series, including patients with complex cardiac abnormalities. Studies of discrete SAS are rare. We therefore sought to review the long-term outcomes of surgical resection of discrete SAS over the last 26 years in a cohort with similar LVOT morphology and an intact ventricular septum.
Section snippets
Patients
The institutional Human Research Ethics Committee at the Royal Children's Hospital (RCH) approved this retrospective study. Between 1989 and 2015, 72 patients underwent fibromuscular resection of discrete SAS at the RCH. Indications for surgery were peak instantaneous LVOT Doppler gradient >30 mmHg and/or progressive AI. Medical records were retrospectively reviewed until last cardiology follow-up. This included inpatient notes, surgical reports and outpatient letters.
Definitions
Discrete SAS was defined as
Patient Characteristics
Of the 72 patients, 37 were male (51.4%, 37/72). Median age at surgery was 5.0 years (2.7-7.6 years) and median weight at surgery was 18.9 kg (13.1-27.6 kg). Three patients had their initial SAS resection performed at other centres and underwent their second procedure (two patients) or third procedure (one patient) at the RCH. These patients were excluded from calculation of recurrence and reoperation rates. Concomitant cardiovascular anomalies are described in Table 1. Eleven patients underwent
Discussion
Surgical resection of SAS was first attempted in 1956 by Brock and Fleming [11]. Most studies of SAS surgical outcomes are mixed series, including concomitant repairs such as VSD closures and aortic valve replacements [2], [9], [12], [13], [14]. We chose to exclude these patients for two reasons. Firstly, VSDs have been shown to be associated with altered LVOT morphology, namely, a deviated ventricular septum, resulting in abnormal flow through the LVOT [15]. This could trigger development of
Limitations
This study is subject to the usual limitations of a retrospective study. Statistical analyses were limited due to the relatively small number of patients and outcomes. Perioperative techniques have varied during the study period.
Conclusion
Resection of SAS provides safe and effective relief of LVOT obstruction in children, with low mortality. Nevertheless, recurrence and reoperation rates remain high, and these patients warrant close long-term follow-up.
References (23)
- et al.
Surgical treatment of subaortic stenosis: a seventeen-year experience
J Thorac Cardiovasc Surg.
(1999) - et al.
Serial hemodynamic observations in congenital valvular and subvalvular aortic stenosis
Am Heart J.
(1975) - et al.
Risk factors for reoperation after repair of discrete subaortic stenosis in children
J Am Coll Cardiol.
(2007) - et al.
The role of enucleation with or without septal myectomy for discrete subaortic stenosis
J Thorac Cardiovasc Surg.
(2009) - et al.
Potential role of mechanical stress in the etiology of pediatric heart disease: septal shear stress in subaortic stenosis
J Am Coll Cardiol.
(1997) - et al.
Subaortic membrane excision: mid-term results
Heart Lung Circ.
(2001) - et al.
Risk factors for aortic valve dysfunction in children with discrete subvalvar aortic stenosis
Am J Cardiol.
(2004) - et al.
Benefits of early surgical repair in fixed subaortic stenosis
J Am Coll Cardiol.
(1997) - et al.
Prevalence and associated risk factors for intervention in 313 children with subaortic stenosis
Ann Thorac Surg.
(2007) - et al.
Long-term pediatric outcome of isolated discrete subaortic stenosis
Can J Cardiol.
(2011)
Evaluation of subvalvular aortic stenosis in children: a 16-year single-center experience
Pediatr Cardiol.
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