What Is Heterotaxy Syndrome?
Heterotaxy syndrome occurs when the heart and other organs are positioned abnormally within the chest and abdomen. This complex heart condition often involves the liver, lungs, spleen, intestines, and stomach.
How Is Heterotaxy Syndrome Inherited?
Heterotaxy syndrome is predominantly sporadic, typically affecting only one family member. However, about 10 percent of individuals with heterotaxy syndrome have a close relative, such as a sibling or parent, who has a congenital heart defect but does not display other features of heterotaxy syndrome. This variation in presentation, where some family members have isolated congenital heart defects while others have heterotaxy syndrome, can be attributed to variable expressivity. This variability may be due to a genetic mutation or a combination of genetic and environmental factors.
Heterotaxy syndrome can be inherited in three different patterns within families:
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Autosomal dominant inheritance implies that a single copy of the altered gene in each cell is sufficient to cause the disorder.
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Autosomal recessive inheritance indicates that both gene copies in each cell have mutations. Although the parents of an individual with an autosomal recessive problem each carry one mutated gene copy, they usually do not exhibit signs or symptoms of the condition.
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In X-linked inheritance, the mutated gene causing the disorder is on the X chromosome.
What Are the Causes of Heterotaxy Syndrome?
The mutation of multiple genes is the leading cause of heterotaxy syndrome. The genetic proteins produced from the genes help guide the location of the organs while development gets mutated, which leads to the abnormal formation of the wrong gene code. All of this occurs in the embryonic stage of fetal development. Heterotaxy is extremely rare, but it does run in the family. There a high chance that genetic and environmental factors blend to produce a mutation in the gene.
Below are some of the causes that lead to heterotaxy syndrome;
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Chromosomal insertions.
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Chromosomal deletions.
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Chromosomal rearrangements.
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Pregnant while suffering from diabetes mellitus.
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Smoking while pregnant.
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Ingestion of cocaine during pregnancy.
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Exposure to specific laboratory chemicals during pregnancy.
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Coming into contact with certain hair dyes or toxins during pregnancy.
What Are the Signs and Symptoms of Heterotaxy Syndrome?
Heterotaxy syndrome generally modifies the structure of the heart. In addition to this, it also disrupts the attachments of the blood vessels that carry oxygenated and deoxygenated blood throughout the body. The bronchi of the lungs, the spleen being abnormal or absent, the liver capturing the position of the stomach, malrotation, and twisting of the intestine are some of the classical signs and symptoms of heterotaxy syndrome.
Below are a few of the classical signs and symptoms of heterotaxy syndrome.
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Bluish discoloration of the lips.
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A bluish tinge of the skin and nails.
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Difficulty in breathing.
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Congenital heart diseases.
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Fast breathing pattern.
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Abnormally slow heart rate.
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Unusually rapid heart rate.
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Green vomiting.
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Frequent infections in the heart.
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Abnormal position of the heart.
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Dextrocardia.
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Mesocardia.
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Holes in the heart walls.
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Defects in the heart valves.
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Transposition of great arteries or TGA.
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Underdeveloped pumping sections of the heart.
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Reduced cardiac output.
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Abnormal heart rhythm.
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Malfunction of the bile ducts.
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Shortage of oxygen in the body.
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Right-sided cardiac apex.
How to Diagnose Heterotaxy Syndrome?
Heterotaxy syndrome is a congenital condition characterized by internal organs such as the heart not being arranged as expected in the chest. A computed tomography (CT) scan reveals the internal organs in detail. A magnetic resonance imaging (MRI) scan can diagnose a more detailed look at the size, location, and other malpositioned factors of the heart and other vital organs.
Echocardiography or electrocardiography will be necessary to determine the exact cardiac situation. In addition, specific tests that evaluate the normal functioning of organs need to be done.
A complete blood picture will also give insight into the heart’s electrical activity. Ultrasounds and endoscopies are also robust diagnostic tools for heterotaxy. Holter monitoring, chest X-rays, and cardiac catheterization are other cardiac imaging tests that can be conducted.
What Is the Treatment for Heterotaxy Syndrome?
The heart is divided into four sections. The upper two heart chambers are the right and left atrium, and the right and left ventricles are the lower sections. Heterotaxy may hamper any or all the chambers of the heart. Since heterotaxy is a syndrome involving multiple organs, treatment is also aligned with correcting all the malpositioned organs. Heart surgery depends on the positions and results of the cardiac diagnostic tools. Any heart defect needs to be immediately managed due to the importance of the organ.
A well-known heart procedure for heterotaxy is the Fontan procedure, where the ventricle of the heart that pumps and transports blood to the whole body is solely corrected. A pacemaker can also be surgically inserted into the heart to manage the abnormal heart rhythm. Prophylactic vaccinations and antibiotic therapy will secure the heart from frequent infections. A heart transplant, being the last option, may also be discussed, but this will require a multidisciplinary approach to patient management.
What Are the Potential Long-Term Consequences of Heterotaxy Syndrome?
The long-term outlook for children with heterotaxy syndrome depends on the timing of diagnosis and the organs involved. Although survival rates have improved, infants undergoing open-heart surgery are at an increased risk of developing lung, liver, and gastrointestinal (GI) diseases, as well as neurodevelopmental issues. Many of them may require a heart transplant later in life. Conversely, individuals diagnosed with heterotaxy syndrome in adulthood typically experience fewer medical complications. Children born with heterotaxy syndrome will require lifelong care from a cardiologist and are likely to need the expertise of several other specialists.
Conclusion
Heterotaxy is a condition that is congenital but may also develop due to certain environmental factors or as a result of other underlying conditions and syndromes. The vital organs are not positioned in their usual expected location in the chest and abdomen. The heart is a major organ malfunctioning due to this syndrome. It has been widely studied that most of the complications and complex cases in patients suffering from heterotaxy are due to the cardiac defects found in them. Current advancements in cardiovascular management of heterotaxy patients with better surgical skills and techniques worldwide will hopefully improve the survival rate and outlook of such patients. Early diagnosis is essential, as is in any condition that involves the heart. Heterotaxy remains among the most challenging congenital defects for cardiologists and pediatric congenital cardiovascular surgeons.
