Elsevier

Heart, Lung and Circulation

Volume 26, Issue 2, February 2017, Pages 179-186
Heart, Lung and Circulation

Original Article
Outcomes of Subaortic Obstruction Resection in Children

https://doi.org/10.1016/j.hlc.2016.05.120Get rights and content

Background

Studies of long-term outcomes of discrete subaortic stenosis are rare. Therefore, we reviewed the long-term outcomes of fibromuscular resection in children with subaortic stenosis over 26 years from a single institution.

Methods

We conducted a retrospective review of all children (n=72) who underwent resection of subaortic obstruction for discrete subaortic stenosis between 1989 and 2015.

Results

Median age at surgery was 5.0 years (2.7-7.6 years). There were no operative deaths but three late deaths (4.2%, 3/72). Overall Kaplan-Meier survival at 10 years was 93.0 ± 3.9% (95% CI: 79.6, 97.7). Peak instantaneous left ventricular outflow tract Doppler gradient decreased from 74.2 ± 36.7 mmHg (16.0-242.0 mmHg) preoperatively to 12.8 ± 7.4 mmHg (2.6-36.0 mmHg) postoperatively (p<0.001). Mean left ventricular outflow tract Doppler gradient decreased from 42.4 ± 17.2 mmHg (12.0-98.0) preoperatively to 7.5 ± 2.7 mmHg (1.4-19.3 mmHg) postoperatively (p<0.001). However, over the mean follow-up period of 7.8 ± 6.1 years (0.1-25.2 years), 29.0% (20/69) of patients had recurrence and 18.8% (13/69) required reoperation at median time of 4.8 years (3.1-9.1 years) after the initial repair. Freedom from reoperation at 10 years was 71.1 ± 7.1% (95% CI: 54.6, 82.3). Risk factors for reoperation were age less than five years at initial repair (p=0.036) and extension of the membrane to the aortic valve (p=0.001). Aortic insufficiency was present in 54.2% (39/72) of patients preoperatively. Progression of aortic insufficiency occurred in 38.9% (28/72). Involvement of the aortic valve at initial repair was associated with need for subsequent aortic valve repair or replacement (p=0.01).

Conclusions

Resection of subaortic obstruction is associated with low mortality and morbidity. Recurrence and reoperation rates are high and progression of aortic insufficiency following subaortic resection is common. Therefore, these patients warrant close follow-up into adult life.

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.

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