Shone’s complex is characterized by multiple obstructive anomalies involving the inflow and outflow of the left ventricle, including supravalvular mitral membrane, parachute mitral valve, subvalvular aortic stenosis, and aortic coarctation. It appears that 10-15% of people with a left ventricular outflow tract (LVOT) defect have a chromosomal defect; recent studies suggest a genetic component to these heart malformations.
It is estimated that there are more than 500 genes that may be important in heart development. Changes in any of the genes may impact how a child’s heart forms. Findings showed an association between the gene ERBB4 and LVOT defects. This gene now joins a previously identified gene, NOTCH1, as a susceptibility gene for LVOT…show more content… The subaortic obstruction may be made worse by thickened papillary muscles.
Clinical manifestations. Symptoms may include failure to thrive, fatigue, tachypnea, tachycardia, poor weight gain, edema and wheezing due to exudation of fluid in lungs. “Loud first and second heart sounds, ejection click, and opening snap may be auscultated” (Shone’s Syndrome, 2012). Pulmonary regurgitation murmur may be present with long-standing pulmonary hypertension.
Types of Shone’s complex. There are two types of Shone’s complex: complete and incomplete. The complete form includes all four congenital heart defects. The incomplete form is two or three of the…show more content… John Shone theorized the compounded effects of supravalvular mitral membrane, parachute mitral valve, subaortic stenosis, and aortic coarctation in 1963 from eight cases. Since then, more cases have been studied and reported. Other conditions may now be included in the diagnostic criteria: cor triatriatum, bicuspid aortic valve, small aortic valve annulus, hypoplastic left ventricle, and small aortic arch.
Prognosis
The prognosis for Shone’s complex is poor, and the survival rate of Shone’s complex varies with the degree of the defects in each individual. Each defect complicates the others, and quality of life is often diminished due to the secondary conditions caused by the defects. Death is often secondary to severe mitral valve disease and the need for multiple surgeries to correct.
Morbidity. It is estimated that 4 to 10 per 1,000 have a cardiac malformation (Pierpont, et al., 2007). Shone’s complex occurs in less than 1% of all congenital heart defects (Shone’s Syndrome, 2012).
Mortality. A study of 27 children reported the 15-year survival rate at 89% (Brown, Ruzmetov, Vijay, Hoyer, Girod, Rodefeld, & Turrentine, 2005). Another study of 45 children reported the 15-year survival rate at 70.3 +/- 8.9% (Walter, Komoda, Siniawski, Miera, Praagh, & Hetzer, 2012). A third study of 121 patients reported the 10-year survival at 86% (Nicholson, et al.,
