Introduction

A large range of congenital illnesses are collectively referred to as chest wall deformities. These may present as discrete disorders or show correlations with genetic syndromes and extra-thoracic anomalies. From infancy through adolescence, there can be detrimental effects that range from psychological cosmetic issues to potentially fatal illnesses. Chest wall deformities do not have a universally recognised classification. Pectus Excavatum (PE), Plectus carinatum, Poland syndrome, Sterna Clefts, Ectopia Cordis, Jeunes syndrome, and Jarcho Levin syndrome are the known deformities. From these conditions, Pectus Excavatum accounts for 90% of deformities of the chest wall.⁶ The cartilage that joins the ribs to the breastbone (sternum) has abnormal growth patterns, which results in Pectus Excavatum, a congenital deformity of the chest wall. A "sunken in” or "funnel chest" appearance results from this, causing the sternum to become depressed.¹ Pectus carinatum, Cleft Sternum, Pentalogy of Cantrell, Asphyxiating Thoracic Dystrophy, and Spondylothoracic Dysplasia are the next most common types.²

Anatomy and pathophysiology

Prevalence and demographics 

Pectus Excavatum is more common in white people and manifests as an isolated, non-familiar deformity. Up to 40% of cases have a familiar, non-syndromic positive history, indicating an autosomal dominant inheritance patron. Genetic syndromes may involve the deformity known as Pectus Excavatum. The most significant associated syndromes found by WBDD (Winter-Baraitser Dysmorphology Database version 1.0.14) and POSSUM (Pictures of Standard Syndromes and Undiagnosed Malformations version 5.7) are Noonan and Marfan. It is critical that secondary Pectus Excavatum, which may require a modified Ravitch procedure for repair, be caused by Poland syndrome rib hypoplasia. An underlying connective tissue disorder is present in less than 1% of cases of Pectus Excavatum. According to data, 80% of cases are diagnosed when the patient is just two years old.⁶ An estimated 1 in 300–400 babies is born with Pectus Excavatum, with a 3:1 male–to–female ratio predominating. Usually diagnosed within the first year of life, the condition is observed from birth in over 90% of cases. 

Physical characteristics 

The onset of symptoms and worsening of the chest's appearance are typically noted in the early teenage years, during a period of rapid bone growth.² With only a visible pectus defect, the patient is typically tall, thin, and in good health when they present clinically. Emphasising: shape of morphological abnormality, coexistence of spine alteration, sternal border pain, and detection of lower rib margin.⁷

Pathophysiology of Pectus Excavatum

Impact on chest wall structure

The cause of Pectus Excavatum in humans is still unknown. However, based on research, it appears to be an inherited disease, with the underlying defect causing the sternum's depression existing from birth. But this deformity appears later in life, usually in the skeletal growth phase. The structure and function of the costal hyaline cartilage are connected to the primordial defect that caused the anterior chest wall to distort. There are two main currents regarding this: the hypothesis of the weak costal cartilage causing the chest wall to collapse and the overgrowth of the costal cartilage theory. This last hypothesis has not been fully proven, although recent histologic, imagistic, and experimental studies suggest it. The process by which a defective growth pattern and modified physical characteristics of the costal cartilages combine to cause PE deformation of the chest wall is most likely a complex one.¹⁹

Effects on cardiac function

The rib cage's anteroposterior dimensions are greatly reduced by the sternal depression that is characteristic of the defect. This reduction makes it more difficult for the heart to expand to the proper extent, which in turn restricts its capacity to raise the stroke volume in response to elevated metabolic demands (such as those encountered during exercise). The heart's displacement and potential rotation of the great vessels could further complicate cardiovascular function.²⁰

Respiratory implications

The rib cage is distorted in Pectus Excavatum patients, which puts them at a mechanical disadvantage despite the fact that none of the respiratory muscle groups are directly affected. This is indicated by the significant decrease in the maximal inspiratory and expiratory pressures (MIP and MEP) of these patients. Although the decrease in respiratory muscle strength is usually not severe, the effects could be much more severe because a higher pressure would be needed to achieve the same level of lung inflation due to the decreased chest wall compliance. Therefore, it's plausible that poor chest wall mechanics, rather than poor lung growth, is the cause of the decreased lung volumes that different researchers have noted.²¹

Ventricular systolic dysfunction is correlated with Pectus Excavatum severity. Pectus Excavatum affects exercise tolerance as well as the systolic function of the left and right ventricles. The best indicators of impairment might be the Haller and correction indices.⁴

Symptoms and diagnosis

Symptoms

Exercise intolerance, tachycardia, and positional and exertional chest pain are common manifestations of Pectus Excavatum. When Pectus Excavatum is severe, it can cause psychological distress, compression of the heart and great vessels, dyspnea and pulmonary restriction. The degree of the pectus deformity is generally thought to be correlated with cardiopulmonary limitations.³ The heart and lungs are under pressure in Pectus Excavatum because of the collapsing chest wall. People start to have breathing problems when exercising gets tough.

They have trouble keeping up with their friends. Adults and children alike may experience anxiety and depression due to their pectus deformity. The symptoms may have an impact on their athletic performance, which may lead to low self-esteem and an avoidance of physical activity and sports. Some pectus patients may avoid activities like swimming where others may see their chest because they feel uncomfortable being stared at or made fun of.⁸ 

Diagnostic methods

A comprehensive assessment is recommended for patients exhibiting symptoms, which may encompass a medical history and physical examination; thoracic imaging (e.g., inspiratory and expiratory computed tomography, magnetic resonance imaging, electrocardiography, echocardiography); blood chemistry analysis (e.g., basic metabolic profile, complete blood cell count, lactate dehydrogenase [LDH] level); cardiopulmonary exercise testing via measurement of maximum oxygen consumption (Vo2); and pulmonary function tests.⁹

Thoracic imaging 

Imaging, especially magnetic resonance imaging or non-contrast computed tomography, should be part of the initial evaluation. These imaging modalities enable visualisation of the malformation and can detect the presence of atelectasis or compression of the tracheobronchial, as well as cardiac displacement and compression. Because the severity of the defect may significantly worsen when a patient exhales, computed tomographic images should be obtained on both inspiration and expiration. Imaging is used to determine the index of severity, usually using the Haller index or the correction index, at the lowest level of the pectus malformation. By dividing the width of the chest by the separation between the anterior and posterior surfaces of the spine, one can determine the Haller index. A Haller index score ranges from 2.5 to 2.7 for normal and from 3.25 to greater for severe. Patients with a more barrel-shaped chest and an incorrectly low Haller index score are better evaluated by the correction index.¹⁰

Echocardiography

Echocardiography should be carried out to rule out significant anatomic abnormalities, even though transthoracic imaging may be limited in patients with severe anomalies. To evaluate the aortic dimensions and mitral valve function in patients suspected of having Marfan syndrome, this imaging is essential. There have also been reports of anatomic anomalies in the mitral valve leaflets and morphologic alterations in the right ventricle, such as a rounded apex, trabecular hypertrophy, structural alterations in the moderator band, and ventricular wall sacculations. Although invasive, transesophageal echocardiography (TEEG) is a better way to evaluate the right side of the heart in PE patients. Significant right-sided heart compression is sometimes present, accompanied by reduced outflow and diastolic dysfunction.¹¹

Cardiopulmonary exercise testing

This test should be done to measure the extent to which PE is influencing a patient's capacity for exercise and oxygen consumption. During exercise testing, an abnormally low maximum anaerobic Vo2 level can indicate cardiac limitations caused by the malformation. According to a study, patients with PE were unable, at any exercise intensity, to achieve the stroke volumes of control patients. As a result, there was a reduction in cardiac output, which limited the amount of peak exercise capacity. Studies have demonstrated that following PE repair, exercise capacity and maximum Vo2 are statistically significantly improved.¹²

Treatment options

Non-surgical approaches

Physical therapy and exercise programs

For mild cases of Pectus Excavatum, there are specific exercises that can help. Your therapist will probably recommend exercises to help you strengthen, breathe better, and move more freely during your physical therapy sessions. Exercises for postural control can also be done. Maintaining good posture and strength as well as lowering the chance of needing surgery for your Pectus Excavatum are the ultimate goals of the exercises. Pectus Excavatum exercises should be performed three to five times a week, and postural awareness exercises (which involve paying attention to your posture and making adjustments) should be performed every day. It is crucial to talk to your doctor or physical therapist about Pectus Excavatum before beginning any exercise program to make sure it is safe for you. These include T-Stretch, Push-Ups, Dumbbell Row, Chest Fly, Seated Twist, Bow Pose, and Camel Pose.¹³ 

Respiratory therapy 

An alternative to surgery for Pectus Excavatum is the application of negative pressure to the thorax. The patient uses a hand pump to apply negative pressure while a vacuum bell is applied to the chest wall defect. Even though there aren't many long-term results, this could work well in the future for managing less serious defects. Furthermore, this treatment would be useful for younger symptomatic patients when prepubertal surgical correction is not desired.¹⁸

Surgical interventions 

Patients with a Haller Index score greater than 3.25 or a correction index score greater than 20% are considered to have severe PE, and surgical procedures are advised. For surgical correction, the mid-adolescent years are generally the recommended age. In addition to lowering the chance of recurrence, repair during this stage enables patients to finish growing.¹⁴

Nuss procedure 

The minimally invasive technique described by Nuss and Kelly involves small incisions made on both sides of the chest for this minimally invasive procedure. Through the incisions, narrow fibre-optic cameras and long-handled tools are inserted. The depressed breastbone is raised into a more normal position by threading a curved metal bar under it. Occasionally, multiple bars are utilized. Three or two years later, the bars were removed.¹⁶

Ravitch procedure

A far larger incision is made down the middle of the chest during this older procedure. After removing the damaged cartilage that connects the ribs to the lower breastbone, the surgeon uses surgical hardware, such as mesh supports or a metal strut, to realign the breastbone in a more normal position. After a year, these supports are taken down.¹⁷

The classic open Ravitch procedure can be used to surgically correct Pectus Excavatum, or the Nuss procedure can be used for minimally invasive repair of Pectus Excavatum (MIRPE). The Nuss procedure is now regarded as the preferred method of treatment because it involves the implantation of a retrosternal bar while the costal cartilages are preserved, remodelling of the sternum, and has significantly lower morbidity—including scarring—than the Ravitch procedure.⁵

Outcomes and recovery

Any kind of surgical repair for Pectus Excavatum carries a risk of recurrence that varies according to the patient's age, the nature and severity of the PE, and the existence of underlying connective tissue disorders. Recurrence rates have dropped to 2% to 5% following the removal of the support bars two to three years after the Nuss procedure. Surgery has been shown to improve self-esteem and quality of life. Patients reported improved health-related quality of life when surveyed following either the Nuss or the Ravitch procedure, with little variation in patient satisfaction between the two surgical techniques.¹⁵

Future directions in research and treatment 

It is imperative to conduct more research on Pectus Excavatum in particular and on chest wall deformities in general. A robust scientific basis is the only one that can offer insights into therapeutic and diagnostic pathways and enable an equitable comparison of results. It also provides a valuable service to our pregnant patients and can be a powerful tool in the fight against occasionally charitable health insurance providers. It is crucial to establish a prospective, (inter-)national data registry. The following topics should undoubtedly be the main focus of research in the upcoming years, even though they are by no means exhaustive.

First, a consensus on the definition and preoperative workup ought to be established.

Second, the physiological effects of Pectus Excavatum, such as those resulting from cardiac compression, need to be proven beyond a reasonable doubt or excluded.

Third, newer analgesic approaches like cryoanalgesia or other cutting-edge techniques like virtual reality therapy ought to be studied more thoroughly, ideally through prospective multicenter cohort studies or randomised controlled trials.

Fourth, for the purpose of preplanning, outcome prediction, and recurrence risk assessment, new methods such as 3D imaging, 3D printing, and artificial intelligence should be investigated and implemented. In order to put value-based healthcare principles into practice, it is also necessary to develop and validate questionnaires and patient-reported outcome measures. Taking into account the perspectives of both the surgeon and the patient, these points may allow us to establish success criteria for Pectus Excavatum repair.

Summary

Chest wall deformities are a group of congenital conditions, with Pectus Excavatum (PE) being the most common, accounting for 90% of cases. PE is characterized by abnormal growth of costal cartilage leading to a sunken chest appearance, typically evident at birth but worsening during adolescence. The condition can cause psychological distress and physiological issues such as reduced cardiac output and restricted respiratory function. Diagnosis involves physical exams, imaging (CT, MRI), echocardiography, and exercise testing. Treatment ranges from physical therapy and vacuum bell use for mild cases to surgical options like the Nuss or Ravitch procedures for severe deformities. While surgical outcomes often improve quality of life and self-esteem, recurrence remains a concern. Future research should focus on standardized definitions, improved diagnostic tools, and innovative treatment methods including cryoanalgesia and 3D imaging.