Congenital Aortic Stenosis in Childhood

Aortic valve stenosis is the obstruction to outflow from the left ventricle because of an abnormal aortic valve. The discharge restriction to the systemic ventricle may also be produced by an anomaly at a sub or supravalvar level. Nevertheless, the most common site of occurrence is by far the annulus (70%). Although congenital aortic stenosis is frequently associated with other significant cardiovascular lesions (20%) such as the hypoplastic left heart syndrome, mitral disease and coarctation of the aorta, we will mainly discuss the isolated congenital aortic valve stenosis in this chapter. Congenital aortic valve stenosis accounts for approximately 5% of all cases of congenital heart disease, with reported incidences ranging from 0.04 to 0.38 per 1000 live births (Botto et al., 2001; Hoffman & Kaplan, 2002). A clear male predominance (Wagner et al., 1977) has been reported, with a gender ratio of 4:1. There is recent evidence of familial predisposition for aortic valve anomalies (recurrence risk ~3% and ~15% in offspring of an affected father or mother respectively). This valvar defect occurs sporadically in most cases however. There is a controversy whether consanguinity has an influence on the incidence of congenital heart disease; while some studies emphasized the increased risk in the rate of congenital cardiac malformations (Badaruddoza et al., 1994; Bassili et al., 2000; Gatrad et al., 1984), others failed to show such association (Robida et al., 1997; Subramanyan et al., 2000). Recent large case series demonstrated that parental consanguinity increases the risk of valvar aortic stenosis as well as atrial septal defect and tetralogy of Fallot, wich supports the involvement of autosomal recessive genes in its bearing (Nabulsi et al., 2003; Chehab et al., 2007). Lately, aortic valvar anomaly in families with autosomal dominant transmission was found to be secondary to a mutation in the NOTCH1 gene (Garg et al., 2005). This apparent contradiction could be explained by the existence of many cases where a gene may be responsible for autosomal recessive and dominant inheritance, depending on the types of mutations. Turner syndrome, a congenital disease caused by structural and/or functional aberrations of the X chromosome, is associated with an increased risk of cardiovascular malformations (Bondy & Turner Syndrome Study Group, 2007). It has been reported that 17 to 59% of the patients carrying this chromosomal alteration are affected with at least one structural cardiovascular anomaly, mainly coarctation of the aorta and bicuspid aortic valve, but also mitral valve disease and dilatation of the aortic root (Landin-Wihelmsen et al., 2001; Sybert, 1998). Although some authors have found no correlation between karyotype and heart