Shone’s syndrome also called as Shone’s complex or Shone’s anomaly, is a rare congenital heart disease described by Shone in 1963. It mainly comprises of a set of four left sided cardiac defects namely supravalvular mitral membrane (SVMM), parachute mitral valve, subaortic stenosis (membranous or muscular) and coarctation of the aorta. Out of these four defects, supravalvular mitral membrane (SVMM) is the first to occur which then causes the development of other three defects. It is an obstruction caused to the inflow and outflow of the left ventricle. So, the prognosis depends on the degree of obstruction that is being caused to the flow of blood.
Shone’s syndrome is a form of heart disease resulting in multiple problems with the left side of the heart and it gets worse over time. Shone’s syndrome is a rare entity that is said to pose a major threat on the left ventricle. There are two types of Shone’s syndrome; they are complete and incomplete Shone’s syndrome. In the complete form of Shone’s syndrome, all the four lesions will be present, whereas in case of incomplete form, two or three lesions will be present.
As discussed earlier, Shone’s syndrome is a rare disorder that is often detected in very young children. The children tend to show symptoms like fatigue, nocturnal cough, and reduced cardiac output by the age of two years. The child will also develop wheezing problem due to the exudation of fluid into the lungs.
The procedure of classifying cardiac lesions in infants is quite difficult. That is why an accurate diagnosis becomes very essential in case of Shone’s syndrome. The diagnosis of Shone’s complex requires an ultrasound of the heart (echocardiogram) and a cardiac catheterization procedure, that is, insertion of a device through blood vessels in the groin to the heart that helps identify heart anatomy. Heart anomalies like abnormal parachute mitral heart valve, a supramitral ring, subaortic stenosis ,that is, narrowing below the aortic valve, and coarctation of the aorta which is, narrowing of a section of the aorta, are usually seen.
MR Imaging is best suited to evaluate patients with Shone's complex. Routine blood tests should be done prior to cardiac catheterization. The surgeons will repair the mitral valve and al the partial surgical removal of supramitral ring is done. This surgical method is preferred to the valve replacement procedure.
The prognosis of Shone’s syndrome is poor, but at recent times due to the advances in cardiothoracic surgery, the survival rate has increased. When treated early, that is, before the onset of pulmonary hypertension, a good outcome is possible in patients with Shone’s syndrome. However, other surgical methods can be employed depending upon the patient’s medical background.