Introduction 

Before we delve into the complexities of pectus excavatum, let’s begin by breaking down the name of this condition. 

Pectus is another word for the chest or the thorax. Anatomically, it defines the area between the neck and the diaphragm.¹ 

To excavate something is to form a hole or a cavity.² 

So, ‘pectus excavatum’ is a medical term used to define a sunken appearance of the chest. Pectus excavatum is a relatively common chest wall deformity, occurring in 1/300 to 1/1000 live births and affecting males more commonly than females.³ This condition can become apparent at birth and develops during the adolescent period. The significance of pectus excavatums prevalence underscores the importance of raising awareness, early diagnosis and appropriate management to ensure the physical and psychological well-being of affected individuals. 

This article thus aims to discuss the definition of pectus excavatum, the fundamental anatomy of the chest, causes and risk factors, symptoms, diagnosis, treatment and complications. 

Anatomy of the chest 

Normal anatomy of the chest

As aforementioned, the thorax or the chest is defined by the neck superiorly and the abdomen/ diaphragm inferiorly. The thorax comprises the thoracic wall, its superficial structures (including the breasts, muscles and skin) and the thoracic cavity.⁴

The thoracic wall is formed from 12 ribs, 12 thoracic vertebrae, cartilage, the sternum and muscles. Functionally it aids in movement, respiration and protection of the internal organs.⁴ The ribs and sternum are of particular importance in pectus excavatum. Since the indentation of the chest is commonly formed from the inward growth of these structures.⁵ It is imperative to understand their anatomy. The sternum is a ‘t-shaped’ bone in essence and forms the central anterior section of the chest wall.⁶ It is divided into three segments: the manubrium (broad superior section), body (middle section) and xiphoid process (narrow distal segment).⁶ The costal cartilages of the sternum connect to the ribs, forming the anterior ribcage.⁶ An in-depth discussion of the thoracic walls superficial structures is not required here due to their simplistic nature. The thoracic cavity consists of various organs and tissues, divided into separate organ systems, such as the respiratory, cardiovascular, nervous, immune and digestive systems.⁴ There are two well established compartments of the thoracic cavity; the pleural cavities and the mediastinum which contain the lungs and other vital structures (such as the heart, great vessels, trachea and essential nerves).^4,7

Thoracic anatomy in pectus excavatum 

Pectus excavatum involves the third to seventh ribs. However, the more severe facet of the deformity occurs in the xiphisternal region.⁸ This congenital condition is commonly asymmetrical and may involve displaced vertebral bodies, in addition to varying levels of scoliosis.⁸ The sternum and ribs can have a significant impact on the organs in the thoracic cavity. For instance, cardiopulmonary and respiratory function can become impaired due to anatomical compression.⁹

Causes and risk factors 

Although the underlying causes of pectus excavatum is not well understood, the abnormal growth of the costal cartilages (connecting the sternum to the ribs) is accepted as the anatomical pathophysiology.¹⁰ A family history of pectus excavatum can often result in a genetic predisposition, supported by a positive family history in approximately 40% of cases.⁸

Conditions associated with pectus excavatum include:¹¹

• Marfan’s syndrome (a connective tissue disorder)
• Noonan’s syndrome (genetic condition inhibiting normal development in various parts of the body)
• Poland syndrome (congenital condition resulting in missing or underdeveloped chest muscles)
• Rickets (softening and weakening of the bones)
• Scoliosis (abnormal curvature of the spine) 

Signs and symptoms

Many people may use the terms signs and symptoms interchangeably; however, they have distinct meanings. They usually differ through the person who is perceiving the condition. For instance, symptoms are manifestations of a condition that the patient is aware of, however, signs are clinical observations that are perceived via a healthcare professional.

Symptoms 

Individuals with pectus excavatum can experience a variety of symptoms, both physical and psychological. For instance:¹²

• Pain (exacerbated by exercise, puberty and growth spurts, poor posture)
• Breathlessness (shortness of breath, tight chestiness possibly worse on exercise)
• Palpitations (can occur in severe cases of pectus excavatum with heart distortion)
• Fainting (during exercise)
• Reduced exercise tolerance 
• Psychological (Impacted self-esteem or confidence)

Signs

During a physical examination of the cardiovascular and respiratory systems, your healthcare provider will note clinical manifestations of the condition. For instance, tall stature, audible murmurs attributed to a defective mitral valve⁸ and most obviously, a sunken in chest. 

Investigations and diagnosis

A clinical diagnosis usually determines the confirmation of pectus excavatum. It involves a physical examination via a healthcare professional that is experienced and familiar with the condition. 

With this, investigations such as blood tests are not commonly conducted for the diagnosis, however radiological assessments and imaging (for instance x-rays) can help to evaluate and assess the severity of pectus excavatum.¹² The most clinically useful imaging method is CT scans, as they are sensitive towards cardiac deformation, rotation and lung compression as a result of the pectus excavatum.¹² MRI can also be used for a diagnosis in children.¹² Other imaging tools used to aid diagnosis are echocardiograms (to assess the heart function) and electrocardiograms (to identify abnormal heart rhythms).¹⁰ Pulmonary or lung function tests can also be performed, however these are usually conducted to assess symptom severity and condition progression.¹⁰

Treatment and management 

There are currently more sustainable and appropriate managements for pectus excavatum, however the severity can determine conclusive treatment options compared to general managements.

Management 

Conservative management options for mild pectus excavatum involve physiotherapy which incorporates exercises aimed to improve posture and chest expansion.¹⁰ Psychological counselling is also a conservative management used to aid those who have difficulty coping with the conditions and its effect on their mental health.¹⁰

Treatment 

Surgical correction is indicated for moderate to severe cases of pectus excavatum, however although these procedures result in improved symptoms and quality of life, they often carry a number of complications and risks that arise with surgery.¹⁰

Following discussion with a healthcare provider, individuals will be able to weigh up the pros and cons of each treatment or management and find a solution that works best for them.

Complications

Complications of pectus excavatum can arise from more severe cases, resulting in impaired cardiopulmonary function. Symptoms of complications can include:⁸

• Chest pain 
• Fatigue 
• Breathlessness on exertion (i.e during exercise)
• Repeat respiratory tract infections 
• Asthma 
• Palpitations 
• Heart murmurs (mitral regurgitation)
• Arrythmias 
• Fainting/ syncope

Summary

Pectus excavatum is a congenital chest deformity that can significantly impact individuals both physically and emotionally. Exploration of the anatomy of the chest, causes of pectus excavatum, signs, symptoms and treatment options has facilitated the comprehension of this condition’s importance. The prevalence of pectus excavatum, affecting a substantial number of individuals potentiates the requirement for continued research, awareness, education and support. Pectus excavatum extends beyond physical implications; therefore, this article aimed to raise awareness and signify the importance of holistic care and the creation of a supportive environment for those struggling with this condition.