Asplenia with cardiovascular anomalies or Ivemark syndrome, also known as Right Atrial Isomerism, is an example of a heterotaxy syndrome

Situs ambiguus

Situs ambiguus or situs ambiguous , also known as heterotaxy, is a rare congenital defect in which the major visceral organs are distributed abnormally within the chest and abdomen.The normal position of the organs is known as situs solitus; situs inversus is a condition in which the usual...

. These uncommon congenital disorders are characterized by defects in the heart, spleen and paired organs such as the lungs and kidneys.

Another name is "asplenia-cardiovascular defect-heterotaxy".

Right atrial isomerism is named for its discoverer, the Swedish pathologist Biörn Ivemark

Biörn Ivemark

Biörn Ivemark was a Swedish pediatrician and pathologist. He is credited with characterizing Asplenia with cardiovascular anomalies, also sometimes known as "Ivemark syndrome"....

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Presentation

In right atrial isomerism, both atria of the heart are morphological right atria leading to associated abnormalities in the pulmonary venous system. In addition, individuals with right atrial isomerism develop asplenia

Asplenia

Asplenia refers to the absence of normal spleen function and is associated with some serious infection risks. Hyposplenism is used to describe reduced splenic functioning, but not as severely affected as with asplenism.-Congenital:...

, a mid-line liver, malrotation of the small intestine and the presence of two morphologic right lungs. Individuals with left atrial isomerism, by comparison, have two morphologic left atria, polysplenia

Polysplenia

-Associated conditions:There are frequent associated congenital anomalies all related to deviations in the development of anatomical asymmetries in early embryonic stages...

, intestinal malrotation and two morphologic left lungs.
The majority of cases present at the time of birth or within a few days or weeks with clinical features of the congenital heart defect (which may including symptoms of cyanosis, breathless, lethargy and poor feeding.)

Causes

The cause of heterotaxy is unknown.

The Ivemark Syndrome Association, which is based in Dorset

Dorset

Dorset , is a county in South West England on the English Channel coast. The county town is Dorchester which is situated in the south. The Hampshire towns of Bournemouth and Christchurch joined the county with the reorganisation of local government in 1974...

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is one of the organisations dedicated to helping sufferrers and funding research.