Recurrence of subaortic stenosis (SAS) after initial resection occurs in up to 20% of cases. Options include re-resection, classical Konno aortoventriculoplasty with aortic valve replacement, valve sparing aortoseptal approach (Vouhe) or – as we suggest – valve sparing conal enlargement with patch augmentation of the sub-aortic region accessed via an infundibulotomy (popularised by Vouhe, initially described by Cooley). Repeated conservative approaches are associated with persisting gradients, heart block, ventricular septal aneurysm and VSD.
Patients
We performed conal enlargement in four children aged 2- 19 years. 3 had a canal defect and previously underwent transaortic resection and myectomy. 1 had Williams syndrome, initially treated for supra AS but subsequently developed muscular SAS.
A conal-enlargement type of resection and patch augmentation of the LVOT was successfully performed with patch augmentation of the subaortic area as described above. Complete relief of obstruction was obtained and no obstruction has recurred. The patient with Williams syndrome later required an aortic valve replacement but the subaortic area did not require further attention. Relief of obstruction has been sustained over a mean of 36 months. No heart block or low cardiac output was observed.
Discussion
The strength of this procedure is effective augmentation of the LVOT and amelioration of angulation which maintains the substrate for later obstruction. Conal enlargement is rarely described beyond the initial reports suggesting that this approach is underappreciated.
In our experience, comprehensive conal enlargement should be undertaken where conservative approaches had previously failed to gain an adequate long term relief of SAS.