Shone complex

from Wikipedia, the free encyclopedia
Classification according to ICD-11
LA88.Y Other specified congenital anomaly of a ventricle or the ventricular septum
ICD-11 ( WHO version 2019)

The Shone complex (also called Shone syndrome) was first described in 1963 by JD Shone together with several colleagues as a combination of congenital heart malformations that are logically related in terms of development. Since then, the joint or partial occurrence of these individual components has been referred to as the "Shone complex". It is a rare congenital heart malformation . The following components were named in the initial description:

Today the term is broader and used for the combination of malformations of the left heart, which include the inflow into the left ventricle, the left ventricle itself, the outflow from the ventricle and the aortic arch . These include (in the direction of blood flow):

However, the full picture of the disease with all the malformations mentioned is rare and its severity varies widely. The diagnosis "Shone complex" is made when several of the named components (inlet and outlet of the left ventricle) are present together. Is z. If, for example, there is a coarctation of the aorta, the diagnosis must be carefully looked for further malformations.

The malformations

  • The malformations of the mitral valve (supravalvular mitral stenosis, parachute mitral valve and Hammock valve) have already been described.
  • The hypoplasia (underdevelopment) of the left ventricle arises in the fetal development because not enough blood flows into the ventricle. It is relatively rare in the Shone complex, but is an important factor in the long-term prognosis.
  • If not enough blood flows through the mitral valve into the left ventricle during the embryonic period, the blood seeks a "bypass circuit" via the foramen ovale and reaches the right ventricle via the right atrium. This increased blood in the right ventricle of the heart can prevent the large gap in the ventricular septum from closing at the beginning of heart development. A ventricular septal defect (VSD) remains . Since sufficient blood flows into the left ventricle through this defect, hypoplasia of the ventricle is prevented.
    Both left ventricular hypoplasia and VSD are relatively rare, but can be easily diagnosed with echocardiography.
  • The subaortic stenosis is a narrowing of the outflow tract of the left ventricle below the flap. It occurs in many anatomical structures. In the case of the Shone complex, the following forms can be identified:
    • a connective tissue membrane that extends from the ventricular septum to the mitral valve leaflets. Often there is also a small VSD
    • Additional mitral valve tissue in the case of a malformed mitral valve, whereby sail-like structures that protrude into the ventricle make it difficult to escape from the left ventricle
    • a tunnel-shaped stenosis in which the ventricular septum (ventricular septum) is significantly thickened and the path of the blood to the aorta is obstructed
    • a displaced ventricular septum : the upper part of the ventricular septum has not grown together with the lower part during development. There is also a larger VSD.
      The first two forms mentioned are common, the latter less common. But what all forms have in common is that they usually only develop in the course of the child's first years of life - subaortic stenoses in infancy are extremely rare.
  • Aortic valve malformations: a "biscupid" (two-lobed - instead of three-lobed) aortic valve may be created, which does not necessarily form a real stenosis, or there is a real aortic valve stenosis .
  • Aortic arch hypoplasia : the entire aortic arch or parts of it are underdeveloped (which is explained by the lack of blood flow in the embryonic development).
  • Coarctation of the aorta

Diagnosis

therapy

If a shone complex is suspected, the therapeutic approach is carefully planned on an individual basis. Coarctation of the aorta is often one of the "leading" symptoms. This can usually be widened without surgery as part of a dilatation with the heart catheter .
If there are several intracardiac malformations, one tries to wait as long as the clinical condition of the patient allows. In the then necessary operation (with the help of the heart-lung machine ) all / many of the individual components are addressed. The mitral valve is often the critical factor and a replacement can often not be avoided in the course of life. There is a risk of AV block intraoperatively , so that a pacemaker must be used.
The subaortic stenosis must be removed early to avoid damage to the aortic valve behind it, and aortic valve replacement cannot always be avoided.

Long-term forecast

In all patients with a Shone complex, numerous operations are to be expected until good hemodynamic conditions are achieved. The goal, however, is to keep the total number of operations as small as possible. In cases with a marginally small left ventricle, there is a risk that the ventricular compliance disorder - despite the anatomically good conditions - will result in (congestion-related) pulmonary hypertension , which in the long term irreversibly damages the pulmonary vascular bed and makes the prognosis doubtful. The only option here is a combined heart-lung transplant.

Lifelong check-ups must be observed and strict compliance with endocarditis prophylaxis must be observed.