Natural history and risk stratification of discrete subaortic stenosis in children: an echocardiographic study.
OBJECTIVE
Discrete subaortic stenosis (DSS) is considered an acquired cardiac defect. However, its clinical course and pathogenesis have not been well defined. This study used echocardiography to investigate the natural history of DSS and identify the possible anatomic abnormalities leading to its development.


METHODS
We reviewed the medical records of 12 children with a diagnosis of DSS between 1988 and 2002. Data on the age at initial diagnosis of DSS was collected and the sequential changes of left ventricular outflow tract obstruction (LVOTO) and aortic regurgitation (AR) were analyzed by serial echocardiographic studies. Patients were divided into 2 subgroups according to the latest or presurgical (in patients with operations for DSS) Doppler-derived peak instantaneous left ventricular outflow tract gradient (deltaP; cut-off point: deltaP 50 mm Hg, our institutional criterion of operation for DSS). The indexed mitral valve (MV)-aortic valve (AV) distance, aortoseptal angle (ASA), indexed DSS-AV distance, and whether the anterior MV leaflet was involved were also determined. The DSS patients were compared with an age- and lesion-matched control group (12 patients).


RESULTS
The mean age at initial diagnosis of DSS was 4.9 +/- 3.7 years. Nine children had disease characterized by milder LVOTO (latest deltaP < 50 mm Hg) and slower progression of LVOTO (mean increase of deltaP, 7.1 +/- 4.4 mm Hg/year) and AR (</= grade I), while 3 children had disease characterized by more severe LVOTO (presurgical deltaP > 50 mm Hg) and more rapid progression of LVOTO (mean increase of deltaP, 27.8 +/- 8.4 mm Hg/year) and AR (>/= grade II). Compared with the control group, the study group had a significantly longer indexed MV-AV distance and a steeper ASA. Compared with the patients with milder disease, patients with more severe disease had a significantly shorter indexed DSS-AV distance and more frequent involvement of the anterior MV leaflet.


CONCLUSIONS
These data indicate that DSS may present with 2 distinct clinical courses. A shorter indexed DSS-AV distance and the involvement of the anterior MV leaflet might be predictive of more rapidly progressive DSS. Longer indexed MV-AV distance and steeper ASA might be useful to evaluate primary cardiac defects and thus to identify patients who are at risk for developing DSS.
Hwang
Mao-Sheng
MS
Department of Pediatric Cardiology, Chang Gung Children's Hospital, Taoyuan, Taiwan.
Chu
Jaw-Ji
JJ
Su
Wen-Jen
WJ
D000293:Adolescent; D001021:Aortic Valve / Q000000981:diagnostic imaging; D002648:Child; D002675:Child, Preschool; D021922:Discrete Subaortic Stenosis / Q000000981:diagnostic imaging*; D015150:Echocardiography, Doppler; D006801:Humans; D008943:Mitral Valve / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D012307:Risk Factors