Heterotaxy Syndrome

This is not a CHD but people with Heterotaxy Syndrome also have a Congenital Heart Defect.

Heterotaxy Syndrome is a complex syndrome that occurs when the axes of the body fail to rotate correctly when developing in the womb. This can result in many different organ systems being affected, and also means that each individual with Heterotaxy is unique. Many individuals have a variety of severe congenital heart disease, while a smaller percentage have minor heart problems or none at all. Some have lung complications, while for others the major concern is their gastro-intestinal or immune system.

Heterotaxy Syndrome is known by several different terms. It can be referred to as situsinversus ambiguous. (Note: situsinversustotalis is a complete reversal of organ placement with no functional abnormalities.) It is also known as Ivemark’s Syndrome, after the doctor who first recognized the pattern of abnormalities. Heterotaxy Syndrome is sometimes called right or left atrial isomerism as well. It often appears that the individual has either two right sides or two left sides, as if the body attempted to make itself symmetrical. Since our internal organs are not symmetrical, this causes several anomalies. It is often classified based on the number or lack of spleens.

Asplenia Syndrome:

Generally speaking, this is the form of Heterotaxy that is also known as right atrial isomerism, in which the patient has two “right sides,” and there is no spleen present (since the spleen is found on the left side in typical anatomy). Due to the lack of a spleen leading to an increase risk of infection, this form is associated with higher mortality rates. This form is also typically associated with more severe heart defects and two trilobed lungs.

Polysplenia Syndrome:

This form is usually paired with the term left atrial isomerism, in which the patient has two “left sides.” Typically, multiple spleens or spleen nodules can be identified. It is important to remember that although these patients may have several spleens, their spleens may not be functioning. A blood test called a Howell Jolly Body test can determine whether the patient has a functioning spleen. If they do not, they are referred to and treated as functionally asplenic. Patients with this form generally have two bilobed lungs, which can mean more severe lung issues. They are more likely to have milder heart defects or none at all. These patients are also more likely to have Primary Ciliary Dyskinesia, which can be associated with either type.

Many patients do not fit neatly into one of these two forms. Some people with severe complex heart defects may have polysplenia, while others with milder to no heart defects have asplenia. The heart defects that are associated with Heterotaxy include: dextocardia, single atrium/atrial septal defect, single ventricle/ventricular septal defect, transposition of the great vessels, common AV valve, total/partial anomalous pulmonary venous return (TAPVR/PAPVR), multiple sinus nodes, endocardial cushion defect, coarctation of the aorta, pulmonary atresia, pulmonary stenosis, and double outlet right ventricle. Many children with Heterotaxy have a combination of heart defects, often including a single ventricle or large ventricular septal defect. For this reason, it is common for a Heterotaxy patient to undergo the staged surgeries, with the final surgery being the Fontan.

The abdominal defects that are associated with Heterotaxy are: duodenal atresia, symmetrical/transverse liver, splenic agenesis, multiple spleens, or spleen abnormality, midline gallbladder, pancreatic malformation, annular pancreas, horseshoe/fused adrenal glands, and malrotation of the intestines. Other health issues associated with Heterotaxy include: scoliosis, eye sight problems, deficiency in serum IgM and IgE, reversal of the frontal and occipital petalia, crossed diaschisis, agenesis/malformation of the corpus callosum, left cerebral hemisphere language dominance and strong right-handedness, and clubbing.

It is very difficult to give a survival rate for Heterotaxy due to the uniqueness of each individual case. Babies born in the 1980’s with Asplenia Syndrome that included severe complex heart disease were given a 10% chance of surviving past their second birthday. Fortunately, with medical technology survival rates have significantly increased. Many children with functional asplenia are on prophylactic antibiotics, usually penicillin or amoxicillin. Some are taken off antibiotics when they turn 18, although many take them for their entire lives. The most concerning time for infections is before the age of five. After about the age of five, the child has been able to develop their immune system enough so that they are not at as high of a risk as when they were younger for catching an infection.

Patients with Heterotaxy Syndrome face many challenges. They see many types of doctors including pediatric cardiologists, pulmonologists, neurologists, immunologists, pediatricians, and gastroenterologists.

Wrote by Mary Elizabeth Thoreson
Vice President of Heterotaxy Hope Organization.
May 2011