Echocardiographic, morphologic, and geometric variations of the left ventricular outflow tract: possible role in the pathogenesis of discrete subaortic stenosis

Long-term follow-up of subvalvular aortic stenosis in children: a single-centre experience

OBJECTIVE

The aim of this study is to evaluate clinical and surgical outcomes of children with subaortic stenosis, to determine the risk factors for surgery and reoperation and to compare isolated subaortic stenosis and those concomitant with CHDs.

METHODS

The study involved 80 children with subaortic stenosis. The patients were first classified as isolated and CHD group, and the isolated group was further classified as membranous/fibromuscular group. The initial, pre-operative, post-operative and the most recent echocardiographic data, demographic properties and follow-up results of the groups were analysed and compared. The correlation of echocardiographic parameters with surgery and reoperation was evaluated.

RESULTS

There was a significant male predominance in all groups. The frequency of the membranous type was higher than the fibromuscular type in the whole and the CHD group. The median time to the first operation was 4.6 years. Thirty-five (43.7%) patients underwent surgery, 5 of 35 (14%) patients required reoperation. The rate of surgery was similar between groups, but reoperation was significantly higher in the isolated group. The gradient was the most important factor for surgery and reoperation in both groups. In the isolated group besides gradient, mitral-aortic separation was the only echocardiographic parameter correlated with surgery and reoperation.

CONCLUSION

Reoperation is higher in isolated subaortic stenosis but similar in membranous and fibromuscular types. Early surgery may be beneficial in preventing aortic insufficiency but does not affect the rate of reoperation. Higher initial gradients are associated with adverse outcomes, recurrence and reoperation.

Imaging adult patients with discrete subvalvar aortic stenosis

PURPOSE OF REVIEW

Distinction between discrete subvalvar aortic stenosis and other causes of left ventricular outflow obstruction has important implications for predicting natural history and guiding the timing and type of intervention. Imaging, primarily transthoracic echocardiography (TTE), plays a pivotal role in the diagnosis and management of adults with subvalvar aortic stenosis.

RECENT FINDINGS

Most systematic research on imaging of subvalvar aortic stenosis has focused on echocardiography. TTE, especially two-dimensional imaging with color and spectral Doppler, remains the main modality for delineation of the anatomic and hemodynamic features of subvalvar stenosis, associated anomalies and involvement of accessory mitral valve attachments to the subaortic septum or abnormally placed papillary muscles. Transesophageal echocardiography may provide more detailed definition of left ventricular outflow tract anatomy, including the presence and extension of the obstructive subaortic fibroelastic tissue onto the aortic or mitral valve, especially in patients with poor transthoracic windows. The clinical role for advanced imaging technologies, including three-dimensional echocardiography, cardiac magnetic resonance and computed tomography, is evolving but, largely because of the adequacy of established imaging with TTE, remains relatively limited.

SUMMARY

In the absence of other congenital heart defects or alternative indications (e.g. coronary angiography), TTE is usually adequate for the assessment of discrete subvalvar aortic stenosis in the adult. In specific clinical situations, supplemental imaging modalities can play an integral role in clinical decision making.

Recurrent discrete subaortic stenosis and small aortic annulus successfully repaired by the Konno procedure in a young woman

A 24-year-old woman who had undergone excision of the membrane for discrete subaortic stenosis when 6 years old displayed recurrent subaortic stenosis and had a small aortic annulus, with a peak pressure gradient of 60mmHg. We chose to perform the Konno operation with a mechanical valve. This released the left ventricular outflow tract obstruction adequately, and she recovered uneventfully with New York Heart Association functional class I. In our experience, an aggressive strategy such as myectomy is an appropriate initial procedure for preventing recurrence when the geometry of the problem may lead to recurrence in the left ventricular outflow tract. The Konno operation is a good option for recurrent subaortic stenosis with small aortic annulus.