Shone's Complex

Introduction
Shone’s complex is a congenital heart disease, consisting of
multiple levels of left sided obstructive lesions including
supravalvar mitral ring, parachute mitral valve, subaortic
stenosis, and coarctation of aorta. This is a very rare malformation
and a very few cases have been reported in literature.


Discussion
Shone’s complex is a rare congenital heart disease described
by Shone et al initially in 1963. It typically consists of four
obstructive lesions of the left side of the heart and circulation
namely parachute like mitral valve, supravalvar mitral ring,
subaortic stenosis , and coarctation of aorta. There is a complete
form of Shone’s complex wherein all the four lesions are present;
however incomplete forms with two or three lesions are also
described. Other coexisting mitral valve anomalies have been
reported such as fused chordae, single papillary muscle and
“typical” (Ruckman & Van Praagh) congenital mitral stenosis.
The LVOT obstruction features may include subaortic stenosis,
valvar aortic stenosis, bicuspid aortic valve, and coarctation of
aorta.

Supravalvar mitral ring is a circumferential ridge or
membrane, which arises from the left atrial wall overlying
the mitral valve and is frequently attached to the mitral valve.
The ring may range from a thin membrane to a thick discrete
fibrous ridge. It may vary in its extent. Adhesion to the valve
may impair opening of the leaflets causing mitral-valve inflow
obstruction in some patients. In other patients, the ring may
be large and protrude into the mitral-valve inflow thus causing
obstruction.

Parachute mitral valve is defined as a unifocal attachment
of mitral valve chordae independent of the number of papillary
muscles. A true parachute mitral valve (PMV) is characterized by
attachment of the chordae to a single or fused papillary muscle;
however PMV also includes asymmetrical mitral valves having
two papillary muscles, one of which is dominant and elongated,
with its tip reaching to the valve leaflets. The unifocal attachment
of the chordae results in a restricted valve opening and subvalvar
obstruction and, rarely, valvar regurgitation. Oosthoek et
al suggested that these morphological features distinguish a
parachute-like mitral valve from a true PMV.

Shone’s complex is a rare congenital anomaly. Fewer than 100
patients have been reported in the literature. It is mostly detected
in childhood as the patient becomes symptomatic by the age of
2 years. The usual symptoms are dyspnea, nocturnal cough,
tachypnea, poor feeding, failure to thrive, fatigue, and signs
and symptoms of heart failure and reduced cardiac output. The
child usually has recurrent episodes of wheezing and respiratory
tract infections due to pulmonary congestion and exudation of
fluid into the lungs. The patient may occasionally present with
acute pulmonary edema.

It is extremely unusual for a patient to remain largely
asymptomatic throughout childhood and get incidentally
detected during adulthood while evaluating for some unrelated
illness. The present case therefore assumes significance. This
patient had been largely asymptomatic (except for NYHA class I
dyspnoea which he had ignored) in childhood. He had presented
to us for meningitis during which his clinical examination
revealed evidence of mitral stenosis along with left ventricular
outflow tract obstruction and aortic coarctation. This prompted
us to investigate the patient in detail. The echocardiographic
findings revealed the features of complete form of Shone’s
complex.

A literature search revealed a few articles mostly case reports.
Goswami et al reported Shone’s anomaly in a young gravid
female mimicking preeclampsia at 25 weeks gestation. Most of
the other reports are in children. Most of these reports are from
foreign literature. To the best of our knowledge the present case
report is the first report of Shone’s anomaly from India.
A good outcome is possible in patients with Shone’s complex,
provided the surgical intervention is undertaken early before
the onset of pulmonary hypertension. Mitral valve repair
along with resection of supramitral ring is preferable over valve
replacement. Other surgical procedures depend upon existence
of associated cardiac anomalies, which ultimately define late
surgical outcome.

Click here for Case Report referenced.