Anatomy Patients with mitral stenosis and aortic stenosis are often referred to as having Shone’s syndrome, although as originally described Shone’s syndrome has four necessary components. Shone’s complex is a term that connotes 2-3 of the components.
- Supramitral membrane in the left atrium. In the most extreme cases, this may be a stenosing, perforated diaphragm above the mitral valve at the mitral annulus. More commonly, this represents a non-obstructive ridge.
- Parachute deformity of MV. Papillary muscles converge on a single papillary head (or narrowly spaced papillaries), which limits MV opening.
- Subaortic stenosis. Usually associated with subaortic flow acceleration due to marked focal hypertrophy (bulging) of the basal anterior ventricular septum, resulting in a fibrous ridge on top of the muscular bulge.
- Coarctation of aorta
Clinically, Shone’s syndrome often creates mitral stenosis, LA hypertension, and restrictive LV physiology. More severe cases fall along the HLHS spectrum of disease.