Abstract During a three years study period (1992-1994), fifth consecutive children with different types of congeniml uortic stenosis were examined by echocardiography at Hungarian Institute of Cardiology (Pediatric Cardiology Department). Out of this study group, 9 cases had supruvalvular aortic stenosis ( 1 .4 % ). Williams syndrome formed 33.3 % of supravalvular aortic stenosis. Our records were determined exclusively on the basis of echocardiography, therefore, we consider them more accurate than the previously reported data.
Supravalvular aortic stenosis is an obstructive congenital deformity of the aorta which originates just distal to the origin of coronary arteries and produced either localized or diffuse narrowing of asccnding aorta ( 1 ). There are three specific anatomic types of supravalvular aortic stenosis: A The membranous type, which consists of a simple fibrous diaphragm containing a single perforation. B The hypoplastic type, which consists of an unifortn hypoplasia of the entire ascending aorta. C The hourglass type, which characterized by extremc thickening of the medial layer of the ascending aorta. Historically Supravalvular aortic stenosis was originally described by the Italian Mencarelli in 1930. In 1958 Denie and Verheug (2) reported 13 pathological examples of this disorder. The designation Williams or Williams-Beuren syndrome have been applied to the distinctive picture produced by coexistence of cardiac and multiple system disorders (3, 4, 5, 6, 7, 8). Cardiac anomalies in Williams syndrome include supravalvular aortic stenosis, narrowing of peripheral systemic and pulmonary arteries. Occasionally, there is moderate thickening of the aortic cusps and valvular pulmonary stenosis (6. 7). Children with supravalvular aortic stenosis appears to be subject to the same risks of unexpected death and infect.ive endocarditis as those with valvular aortic stenosis (9). Studies of the natural history of supravalvular aortic stenosis indicate that the aortic lesion is progressive due to poor growth of ascending aorta ( 10).
PATIENTS AND METHODS
Case reports were collected retrospectively from the medical archives of pediatric-cardiology department in the Hungarian Institute of Cardiology, Budapest. The study group included 664 consecutive children with different types of congenital aortic stenosis. The study period was three years ( 19921994). All cases were exarnined successfully by echocardiography. Two-dimensional echocardiographic parasternal long and short axis view was used to determine the types of congenital aortic ste
nosis. Continuos-wave Doppler echocardiography was used to determine the pressure gradient across supravalvular aortic stenosis by applying the modified Bernoulli equation. Three cases had preoperative cardiac catheterization and angiocardiography. This was to localize the site of obstruction, assess hemodynamic abnormality, delineate coronary anatomy and visualize the presence of associated peripheral pulmonary stenosis.
RESULT Out of the study group (664), there were nine cases that had supravalvular aortic stenosis and formed only 1 .4 % of the total cases (Table l. and Figure I ).
Six cases had hourglass type (67 %), two had membranous type (22 %) and one had hypoplastic type ( 1 1 %). One case was associated with peripheral pulmonary stenosis and one with valvular aortic stenosis. Age ranged from 1 .5 to 16 years (mean 9.4 ± 4 years). Male to female ratio was 2: 1 (Table ll.). Williams syndrome formed 33.3 % of the supravalvular aortic stenosis (Figure 2). All of these cases had echocardiographic examination (Figure 3). Three cases were operated and these had preoperative cardiac catheterization and angiocardiography (Figure 4). Doppler peak-instantaneous pressure gradient for operated cases ranged from 74 to 144 mm Hg (average 100 ± 38 mm Hg), while for nonoperated cases the gradient ranged from 16 to 77 mm Hg (average 33 ± 24 mm Hg). The catheter peak-to-peak pressure gradient ranged from 65 to 100 mm Hg (average 80 ± 18 mm Hg).
DISCUSSION
Although a number of clinical features may suggest the presence of Supravalvular aortic stenosis (4, 5), the precise diagnosis of Supravalvular aortic stenosis and its differentiation from valvular or subvalvular obstruction require echocardiography. In a study ot the types of stenosis occurring in the region of the aortic valve Supravalvular aortic stenosis has represented between 0.6 and 6 % of the cases examined ( l, 5, 13).
In or series, Supravalvular aortic stenosis was the least common type of congential aortic stenosis forming only 1.4 alo. Hourglass type was the most prevalent one, followed by membranous type and lastly the hypoplastic type. Williams syndrome formed 33.3 % of Supravalvular aortic stenosis. Our epidemiological findings were determined on the basis of the echocardiography, therefore, considered more accurate than the previously reported data. Children with a peak-topeak pressure gradient of more than 75 mm Hg are considered to have severe aortic stenosis. These patients are considered to be candidates for interventions, even without symptoms and without T wave changes, and children with peak-to-peak pressure gradient of more than 50 mm Hg at rest together with symptoms and T-wave changes on resting or exercise electrocardiography are also considered to be a candidates for interventions. In our study, Doppler peak-instantaneous pressure gradient for operated cases ranged from 74 to 144 mm Hg (average 100 ± 18 mm Hg), while catheter peak-to-peak pressure gradient ranged from 65 to 100 mm Hg (average 80 ± 18 mm Hg).
Some investigators ( I 1 , 12) emphasized the extraaortic extent of supravalvular aortic stenosis, particularly the presence of coronary obstruction and the development of ischaemic heart disease even in childhood. Early surgical intervention can minimize the degree of proliferation of dysplastic tissue, thereby decreasing the risk of myocardial ischemia ( 12). Balloon dilatation of supravalvular aortic stenosis was reported with some success only in the membranous type of Supravalvular aortic stenosis ( 14).
Abhreviations used in tables and ti,oere.s: AS = aortic stenosi.s.
DopPler Gradienl = Dnppler Peak-irtstantunoou,c pe.c.suro ,radient in ntm H,,
Catheter,radient =Peak-t°-peuk lrre·.ssuro ,radinnt in mm H,. M = Malo, F = Female. W,S = William.s syndrnrru·.
pt. No: = patient·s numbc·r,
PPS = Poripheral hulmonary ste rusis. VAS = ralrular a°rtic' steno.sis.
+ indicate.s ca.se,s that had sur,c·V.
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