What is Heterotaxy

Heterotaxy, or Situs Ambiguous, refers to the abnormal arranging of the body organs. This is different from Situs Inversus (mirror image of situs solitus/reversed from left to right) or Situs solitus (the normal position of the organs & vessels w/in the body).

The following may be assocaite w/Heterotaxy

Congential Heart Diseas: Cardiac looping malformations – commonly Fallot’s tetralogy, transposition of the great vessles, pulmonary valve stenosis, and ventricular and atrial septal defects.

Abnormal postion of the body’s organs - the stomach and spleen are particularly prone to isolated reversal, and the stomach, liver and a single adrenal gland are occasionally found in the midline.

Organ malformations (part of the body is misshapen or malformed) Spleen: asplenia (no spleen) – polysplenia (many spleens) and more rarely a failure of the head of the pancreas to form, and horseshoe adrenals and kidneys

Rotation errors, causing volvulus and/or faulty peritoneal attachments.

More rarely, vascular abnormalities (related to blood vessels) are found, including interrupted inferior vena cava, bilateral superior or inferior venae cavae, intrahepatic interruption of the inferior vena cava with connection to the azygos or hemiaxygos veins, and aberrant portal veins.

Other terms used in Heterotaxy are cardiac (heart) positions: malposition (used to describe both the location of the heart), dextrocardia (refers to the heart being situated on the right side of the body), levocardia (normal position), and mesocardia (heart in the middle of the thorax).

Complications from Asplenia or Polysplenia Syndrome are: increased risk of congenital heart disease, immune deficiency (this is due to splenic absence or function of the spleen), and catastrophic volvulus with malrotation (twisting of the intestines) are due to severity of this disease.

What is a spleen? The spleen is located in the abdomen of the body; the function of the spleen is to destroy old red blood cells & holds a basin of blood. The spleen plays a role in the immune system. The spleen helps clear bacteria from the bloodstream. A patient with Asplenia is at significant risk for life-threatening infections & fulminant sepsis especially for the 1st 2 years of life. Also a person with Polysplenia can have a functional asplenia where the spleen is not working at a 100%. It has been noted that after age 6 months, Streptococcus pneumoniae and Haemophilus influenzae type b may cause fulminant sepsis; Neisseria meningitides is less common. Malaria, babesiosis, and certain viral infections may also be more severe in individuals with asplenia. The younger the patient at the time of splenic function loss, the higher his or her risk for serious infection.

Asplenia: Asplenia is most often found in alliance with other anomalies. Such as Ivemark syndrome, this is also known as asplenia syndrome. Visceral Heterotaxy is present with bilateral right-sidedness. The right-sided organs are duplicated, and organs that are normally present on the left side are missing.

Polysplenia: The stomach may be on the right side, and multiple spleens are found along the greater curvature. Absence of the hepatic portion of the inferior vena cava with an azygos venous connection is distinctive. Information regarding how well the spleen works is limited. Reports vary from suboptimal function to normal function. Accessory spleens should be distinguished from polysplenia. In polysplenia, a normal spleen with multiple spleens involvement is not present. This is why they call it a functional Asplenia. Accessory spleens are usually located in the hilus of the normal spleen or in the tail of the pancreas. The accessory splenules are typically tiny and clinically unimportant, but they may become hypertrophied in specific situations. Polysplenia may be regarded as bilateral left-sidedness, and it may be associated with left atrial isomerism (syndrome in which generally unpaired organs, develop more symmetrically in mirror image; two or more spleens, one on each side, are usually noted, and cardiovascular anomalies are frequent).

For more information on Heterotaxy with Asplenia or Polysplenia please see websites noted below. This is where a lot of my information comes from (you know I did not come up with all this on my on). I just took what I thought was easier to understand for my readers.

http://www.emedicine.com/PED/topic2513.htm
http://www.emedicine.com/ped/topic2514.htm
http://radiographics.rsnajnls.org/cgi/content/full/19/4/837