Abstract
Despite of significant progress in immediate results of biventricular repair of complex congenital heart defects with the anomaly of conotruncus, some patients develop late complications that require repeat surgical
correction. Subaortic obstruction is one of those complications.
The aim of presented retrospective study is to reveal the causes of secondary subaortic obstruction and to
analyze the immediate results of corrective surgical interventions.
Mateirial and methods. During the years 1999-2013, 17 patients previously subjected to the repair of congenital
conotruncal defects were diagnosed to have subaortic obstruction. Conotruncal defects included double
outlet right ventricle (n=7), tetralogy of Fallot (n=4), transposition of the great arteries with ventricular
septal defect (n=3), double-chambered right ventricle (n=2) and type 1 truncus arteriosus (n=1). The age of
patients at complete repair of these defects and at the repeat surgical intervention aimed to relieve subaortic
obstruction ranged from 4 months to 13 years (median, 3.4 years) and from 3.5 to 45 years (median, 10.6
years), respectively. The interval between the primary repair and the correction of subaortic obstruction
ranged from 3 to 36 years (mean, 7.7±3.9 years). The following operations were performed as a repeat surgical
intervention: resection of subaortic membrane (n=3), myectomy (n=1), resection of the membrane
combined with myectomy (n=10), enlargement of the ventricular septal defect with placing a patch (n=2)
and aortoventriculoplasty by Konno with aortic valve replacement (n=1). Concomitant surgical procedures
included reconstruction of the right ventricular outflow tract (n=8), closure of ventricular septal defect
(n=4), and atrioventricular valve repair (n=3).
Results. The following causes of subaortic obstruction were revealed: discrete fibromuscular stenosis or circular
membrane (13/17 or 76%), hypertrophy of the conal septum (1/17 or 6%), isolated hypertrophy of the
ventricular septum (1/17 or 6%), deformation ofthe tunnel between left ventricle and aorta (1/17 or 6%) and
tunnel type stenosis in combination with “narrow” fibrous annulus of the aortic valve (1/17 or 6%).
Diameter of the left ventricular outflow tract and systolic pressure gradient between the left ventricle and the
aorta prior to the correction of subaortic stenosis was 10.4+2.9 mm (range, 6-18 mm) and 96.2+31.4 mm
Hg, respectively. Fifteen patients survived the operation, did not have any complications in early post-operative
period, and were discharged from the clinic. Two patients (11,8%) died from multiple organ failure.
Normal sinus rhythm was preserved in all the cases. The diameter of the left ventricular outflow tract at discharge
enlarged up to 18.7+2.4 mm (range, 15-24 mm, p < 0.01 if compared to pre-operative values). On
the contrary, the systolic pressure gradient between the left ventricle and the aorta at discharge lowered down
to 16.1+9.6 mm Hg (range, 2-45 mm Hg) (p<0.01).
Conclusion. The most common cause of subaortic obstruction developed after complete repair of congenital
conotruncal defects is combination of subaortic membrane and fibromuscular stenosis. Subaortic
obstruction is often accompanied by obstruction of the right ventricular outflow tract. Repeat surgical intervention
aimed to eliminate subaortic obstruction is a safe procedure that provides good immediate results.
The follow-up examination is needed to assess the late results of this corrective surgery.
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