Is pectus excavatum hereditary?

Written by Zhang Zhi Gong
Cardiothoracic Surgery
Updated on September 04, 2024
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Is pectus excavatum hereditary? According to modern genetic medicine, actually, about 80% of diseases are related to genetics to some extent, and pectus excavatum is no exception. Normally, pectus excavatum occurs in about one in 400 to 1000 people, with a higher prevalence in males. Research has also found that pectus excavatum is often seen in several genetic disorders, including Noonan syndrome, Turner syndrome, and Marfan syndrome. This indicates that it shares certain genes with these genetic disorders, such as the fibrillin-1 gene and others in the RAS/MAPK pathway. These genetic correlations may not always be evident, for example, the parents may not have pectus excavatum themselves. However, when parents with these recessive genes reproduce, their combination might result in pectus excavatum in their child. The development of pectus excavatum might be related to abnormal asymmetrical development of the cartilage. Thus, there is indeed a certain correlation between pectus excavatum and genetic factors.

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Written by Zhang Zhi Gong
Cardiothoracic Surgery
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Pectus excavatum heart hazards

Pectus excavatum can harm the patient's or child's heart, primarily manifesting in compression of the heart and affecting the function of the internal heart valves. Imagine a normal person's rib cage, which is oval in cross-section. There is a certain ratio between the lateral diameter and the anterior-posterior diameter, with normal individuals having a ratio of less than 2.5. However, in patients with pectus excavatum, this anterior-posterior diameter is significantly compressed, meaning the sternum moves closer to the spine, compressing inward and backward, squeezing the heart - this is the first step. The heart itself is a contractile muscular organ, its purpose being to eject blood and circulate it throughout the body. If the sternum and spine directly compress the heart, preventing it from fully expanding, then blood cannot fully flow back into the heart, and thus the ejection or pumping function of the heart will be impacted. Secondly, besides the heart being compressed, just like a house becoming deformed from being squeezed, the doors within the house cannot function properly; they cannot close or open well. Thus, pectus excavatum not only compresses the heart itself but also severely harms the function of the heart valves, even causing mitral valve prolapse in some patients.

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Written by Zhang Zhi Gong
Cardiothoracic Surgery
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Causes of Pectus Excavatum

Although current medicine has developed to the molecular and genetic levels, the true causes of many modern diseases are still not completely clear, which includes pectus excavatum. There have been medical cases indicating that scientists have never ceased to explore the causes of pectus excavatum. It was once believed by early medical scientists that pectus excavatum might be caused by the inward and backward pulling of the sternum by the diaphragm. Therefore, for a period, the treatment for pectus excavatum involved releasing adhesions of the diaphragm, but this method was later found to be ineffective for children and was abandoned. Subsequently, it was discovered that pectus excavatum is somewhat related to the genetics of many families, such as those with Marfan syndrome (an autosomal dominant hereditary connective tissue disorder) and Noonan syndrome (a genetic disorder caused by mutations). However, no definitive pathogenic genes have been identified in families with sporadic cases of pectus excavatum. In summary, pectus excavatum is currently believed to be possibly caused by factors such as the development of rib cartilage on both sides, genetics, and other acquired conditions, like underdeveloped laryngeal cartilage or post-surgical factors from congenital diaphragmatic hernia repair. Overall, the causes of pectus excavatum are still actively being explored by medical scientists.

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Written by Zhang Zhi Gong
Cardiothoracic Surgery
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Does pectus excavatum require surgery?

The decision on whether surgery is needed for pectus excavatum depends on the patient's age, the severity of the deformity, and the elasticity of the chest wall. If the patient is very young, under one year old, and the pectus excavatum is not very severe, we recommend a watchful waiting approach. In patients with pectus excavatum under one year old, it is possible that the condition is pseudopectus excavatum, which may improve as they grow and develop within the first year. However, not everyone improves, with about one third of the cases showing improvement within the first year. If the child is older than one year, the likelihood of improvement is basically none, and at this time, conservative treatment using a pectus excavatum suction cup can be considered. If adhered to effectively, the suction cup can have a certain effect for some patients with pectus excavatum. But if the patient is over three to five years old and the chest wall has matured, surgery should be considered. Therefore, for the vast majority of patients with pectus excavatum, surgery is a relatively definitive and immediately effective method.

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Minimally invasive surgery for pectus excavatum

Pectus excavatum minimally invasive surgery currently comes in two varieties. The first resembles a variation of the traditional Nuss procedure, which involves making a small incision under the patient's armpit and inserting a pre-shaped trapezoidal steel plate through this small hole to the back of the depressed breastbone. The steel plate is then flipped to push out the depression. Because it requires only a one to two centimeter incision on the patient, it is considered much less invasive compared to the traditional Nuss procedure which requires two incisions. There is also another type of minimally invasive surgery which involves bilateral incisions but does not require flipping the steel plate, thus avoiding damage associated with flipping and muscle disruption between the ribs. This is also considered a current minimally invasive surgical technique. Additionally, there is the recent Wang procedure, which is also minimally invasive, requiring only one incision and not necessitating access behind the breastbone. However, it is generally suitable only for younger patients with softer breastbones. For older adults, the Wang procedure might not be appropriate and further observation is required.

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Best age for pectus excavatum surgery

The best age for funnel chest surgery, according to the latest and most authoritative ninth edition of the surgical textbook, is between three and five years old. Historically, there has been controversy over the best age for funnel chest surgery, with some pediatricians previously believing it should wait until adolescence. However, it has been found that by the age of five, children start to become more aware and might realize their chest shape differs from others, potentially leading to feelings of inferiority and reluctance to make friends. Thus, performing the surgery before the age of five—before the child is fully aware of their deformity—might actually be preferable, as it could minimize psychological and physiological impacts. Of course, there is also a viewpoint supporting surgery before the age of three, but the younger the child, the softer the chest bone, which sometimes allows for other potential corrective methods.