Blood cyst in the heart is a very rare finding and was first reported by Elasser
in 1844. The cysts are most commonly present on the supporting
structures; atrioventricular valves, accounting for 96% of the cysts in
infants, and are less often present on pulmonary and aortic valves.
Histologically,
it is thin-walled and normally lined by cobblestone-shaped endothelial cells
and does not contain any tumorous cells.
Blood
cysts are often asymptomatic, small and congenital. The cysts regress
spontaneously in most patients and are consequently rare in adults, there are
some cases reported in contrast. Cyst
growth potential complications include valve dysfunction, left ventricular
outflow tract obstruction, and embolic stroke have been documented.
In differential
diagnosis primary cystic tumor such as
hemangioma or myxoma should be taken into account and the right-sided cystic
mass includes
aneurysmatic
atrioventricular septum, cavitating thrombus, abscess formation as a process of endocarditis, hydatid cyst, and blood cyst.
However,
absence of intracystic calcification, homogenous pattern of cystic
fluid, relation
to the tricuspid valve, and clinical history strongly suggested a blood cyst in
our patient.
Echocardiography indicated the cystic nature of the tumor which is highly
mistaken with cardiac hydatidosis. However, cardiac MRI was important for its
diagnosis.
Hydatid cysts
exhibit a different behavior under MRI, being a
a round
homogeneous image is observed with signs of bleeding (iso- or hyperintense in
T1 and iso- or hypointense in T2) with no uptake of IV contrast media, which
indicates its hematic and cystic nature
Because of the
cyst’s location, a myxoma could be suspected, but myxomas tend to be
heterogeneous, and although some may exhibit a more homogeneous behavior, they
always exhibit contrast uptake, being solid lesions.
A chronic
thrombus may have similar intensity in T1 and T2, but its round morphology, its
well-defined margins, the presence of a tiny pedicle, and its cystic nature as
revealed by MRI and echocardiography do not support this diagnosis.
Although a
cardiac blood cyst is a very rare finding, it can
be diagnosed
using cardiac MRI and it should be included in
the
differential table of masses inside heart cavities.
There are several purposed mechanisms for formation of cystic mass
,however, it is believed that invagination at crevices
of the valve surface into stroma by high ventricular pressure may result in
blood-filled cyst formation. Subsequently, the mouths
of the crevices may fuse to form a closed cyst.
The
followings are hypotheses :
The first is that blood
cysts are formed during valve development as a result of blood being pressed
and trapped in crevices that are later sealed off.
The second hypothesis is
that blood cysts are the result of hematoma formation in the subvalvular region
secondary to the occlusion of small vascular branches of end arteries due to
inflammation, vagal stimulation, anoxia, or hemorrhagic events.
The third hypothesis
involves possible heteroplastic changes in the tissue that comes from primitive
pericardial mesothelium.
The fourth and fifth
hypotheses are that these blood cysts simply represent ectatic or dilated blood
vessels in the valve or that they represent angiomas.
However, there is still
no consensus regarding the development of blood cysts.
Dencker et al suggested
that a conservative approach in asymptomatic patient with minor cyst, and
surgical resection should be considered if symptoms exist or if the cysts lead
to any cardiac dysfunction.
References
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2)
Jose VJ, Gupta SN, Jose S, Chacko B, Abraham PK, Abraham OC et al. Blood-filled cysts of heart. Indian Heart J 2004;56:174–5.
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Shing M, Rubenson DS.
Embolic stroke and cardiac papillary fibroelastoma. Clin Cardiol 2001;
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Prasad A, Callahan MJ, Malouf JF. Acquired right atrial blood
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López-Pardo F, López-Haldón J, Granado-Sánchez C, Rodríguez- Puras
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