Definition of Pectus Excavatum

Description of the condition

Pectus excavatum is a congenital chest wall disorder and happens when a person’s sternum and ribs (the breastbone) grow inward, leaving a concave shape. Other names include sunken chest or funnel chest. Pectus excavatum can have physical and mental implications on patients. This article will explore how pectus excavatum can cause breathing problems and present the impact of treatment options.

Prevalence and demographic information

Pectus excavatum is the most common chest wall abnormality, making up 90% of all chest wall deformities.¹ The condition is more prevalent in those biologically male, being 5x more present in males than females.² Pectus excavatum appears in 1 in 300 to 1 in 1000 births, making it a relatively common condition.

The specific causes and therefore the risk factors are not yet known, however, researchers suspect what may make some individuals more likely to have the condition.

Pectus excavatum is an inherited disorder with the inheritance being multifactorial;³ meaning the condition isn’t caused by a single gene, but a lot of different factors can affect whether a child will inherit the condition. Around 40-53% of people with pectus excavatum have a family member who also has the condition.⁴

Pectus excavatum may develop as part of a rare musculoskeletal condition such as Marfan syndrome, Ehlers-Danlos syndrome⁴ or Noonan syndrome.⁵ Scoliosis is also present in 1 in 10 people with pectus excavatum.⁵

Importance of studying the relationship with breathing problems

Impact on quality of life

Individuals with pectus excavatum may experience difficulties which impact their daily life. The Cleveland Clinic describes the common breathing problems associated with the condition:

• a lower tolerance to exercise due to shortness of breath
• chest pain
• lowered stamina
• increased fatigue

Anatomy and Pathophysiology of Pectus Excavatum

Normal thoracic anatomy

Structure and function of the rib cage and sternum

The sternum and ribcage protect the lungs and the heart. When they are at their usual convex angle, the breastbone and ribs move outwards and upwards when we take a breath in. This makes room for the expanding lungs.

The connective tissue connecting the sternum to the ribs supports this movement and provides the elasticity needed for the chest to expand. However, it is also a tough tissue which keeps the ribs securely attached to the sternum.

The heart is what pumps this oxygen-filled blood from the lungs around the body. It also circulates used blood from organs back to the lungs to be replenished. These actions are essential for effective breathing. To carry out its role, the heart needs enough space in the chest cavity.

Anatomical changes in pectus excavatum

Deformity characteristics

In pectus excavatum, there is an abnormal growth of this connective tissue surrounding the sternum and the ribs. As the connective tissue grows too much, it causes a depression of the sternum, leading to a ‘sunken’ appearance.⁶

Variability in severity

Not all patients with pectus excavatum will experience breathing problems. Individuals with a milder chest depression usually do not experience these symptoms.⁶ Those with moderate to severe cases may experience the breathing problems mentioned in the Introduction section. In severe cases of pectus excavatum, compression of the heart and lungs may occur.⁶

Breathing problems associated with pectus excavatum

Types of breathing problems

Dyspnea (shortness of breath)

Shortness of breath or chest tightness, especially on exertion, are common symptoms. Both chest pain and back pain are common and this is likely related to a musculoskeletal cause. This pain and shortness of breath may be partly caused by the poor posture associated with the condition.⁷

Reduced exercise tolerance

In daily life, individuals with pectus excavatum may not experience symptoms. Yet when more oxygen is needed during intense exercise, symptoms may appear.⁸

As the lungs struggle to expand, the body tries to compensate by engaging the diaphragm to help the lungs expand. This type of breathing requires more effort and is therefore one of the reasons for the fatigue experienced by people with pectus excavatum. Individuals may struggle to carry out exercises as intense as their peers.⁸

Mechanisms of breathing impairment

Mechanical limitations

Decreased lung volume

For most people with pectus excavatum, their lungs don’t work as well as they should. Although some simple tests might not show normal pulmonary function, advanced tests, especially during exercise,e show a relationship between breathlessness on exertion and a lower lung reserve.⁷ Studies show lower results on lung function tests including the FVC, FEV1 and FEF 25-75;⁹ all measure of the amount of air someone can forcefully exhale.

Impaired chest wall movement

The effect on lung volume may be due to the abnormally rigid rib cage present in the condition.¹⁰ The excessive connective tissue and the indentation prevent the lungs from expanding.

Cardiopulmonary interactions

Cardiac compression

Severe depression of the breastbone can limit the space in the chest. This can especially be a problem during breathing when the lungs need this extra room to expand. Furthermore, the heart may also become compressed, which will push it further onto the left side of the chest and limit how well it can pump blood around the body.¹⁰

Along with the compression of the heart, occasionally the close interaction between the sternum and the pulmonary artery can cause a heart murmur⁸.

Severe heart compression can result in palpitations because of distortion of the normal form of the heart. Although rare, this distortion of the heart can also cause some people with pectus excavatum to feel faint or actually faint during intense exercise.⁷

Cardiac output may be reduced because the compression of the heart prevents the blood from filling and therefore reduces the blood going out. This means less blood is efficiently delivering oxygen to the body.¹¹

Clinical presentation and diagnosis

Physical examination findings

The diagnosis of pectus excavatum is a clinical diagnosis where a doctor will examine the chest and diagnose pectus excavatum by the depression of the breastbone.

The lower sternum is usually most affected and the deformity might be associated with rib flaring or rib flattening. There are different ways to describe the type of deformity like trench-like, cup-shaped or saucer-shaped.⁷

Treatment options are informed by the type of pectus deformity, its severity and whether the deformity is present alone or as part of a syndrome.

The condition may not be noticed until after puberty, when the deformity becomes more prominent during growth spurts and might increase symptoms.

Diagnostic tools and techniques

Imaging studies

There is no specific test to diagnose pectus excavatum. X-rays may tell us how severe the condition is and whether any associated conditions are present such as scoliosis.⁷

A CT scan is the best option as it can tell us how severe the pectus excavatum is more accurately and how much the heart and the sternum are displaced. It is useful in deciding between the Nuss procedure or the Ravitch procedure.⁷

An MRI test is a useful alternative test.⁷

Other tests

Tests such as pulmonary function tests (PFTs), cardiopulmonary testing (CPET) or heart ECGs are not usually carried out unless severe symptoms are present or associated conditions such as Marfan’s syndrome are suspected.⁷

Treatment options and their impact on breathing

Non-surgical treatments

Physical therapy and exercises

Non-surgical treatments can be used to manage symptoms such as posture and exercise programs as well as bracing.¹²

Vacuum bell therapy is an intervention which can help alleviate the depression of the sternum through a suction cup in milder cases.¹²

Surgical Treatments

Surgical treatments are usually used when severe pectus excavatum compresses the lungs and heart so much it can cause life-threatening symptoms.¹²

Studies have shown that surgical treatment for severe pectus excavatum has been effective in improving lung reserve and exercise tolerance, however, this hasn’t been true across all studies.⁷ Similarly, for cardiac function resulting from compression of the heart; although not universal, some studies have shown an improvement.⁷

Nuss procedure

The Nuss procedure is minimally invasive and places steel bars through small holes in the chest just under the sternum to elevate the depression of the breastbone.¹²

• Impact on respiratory function

Both surgeries can reduce the compression on the heart and lungs and therefore reduce breathing difficulties.

A study found that after the Nuss procedure, the movement of the chest wall which allows air to be taken up into the lungs is indistinguishable from that of someone without pectus excavatum.⁹ Furthermore, the lung volume (intrathoracic volume) is increased and an improvement in pulmonary function tests is seen.⁹

Ravitch procedure

The Ravitch procedure, or open correction, is more invasive and involves cutting away the excessive connective tissue of the ribs and flattening the sternum. Unlike in the Nuss procedure, the bars which are inserted are permanent.¹²

• Impact on respiratory function

A study showed that the impact on how much air can be forcefully exhaled (FEV1, FVC) as well as vital capacity and total lung capacity were similar 1 year after the Nuss and the Ravitch procedures.¹³

However, the results years after surgery and bar removal of the Nuss procedure showed more improvement in lung function.¹³

Both surgeries have possible complications which are important to be aware of.

Prognosis

Both the Nuss and Ravitch procedures have great results which significantly improve the depression of the sternum and the associated breathing symptoms in most patients.⁴

Symptoms can not only get worse during puberty but also as individuals grow older as it makes it harder for the body to compensate for the reduced heart and lung function.⁴

Summary

Pectus excavatum is the most common congenital chest wall disorder and can cause breathing problems due to the depression of the breastbone. This may cause compression of the heart and lungs. Treatments such as the Nuss or Ravitch procedure can alleviate symptoms.