Congenital Chest Wall Deformities
Pectus excavatum, also known as an ‘excavated, sunken, or funnel chest,’ is the most common chest wall anomaly, constituting about 80% of deformities seen at our hospital (Table 20-1). Pectus carinatum, a chest wall protuberance, comprises approximately 12% of chest wall deformities, whereas combined excavatum/carinatum deformities are found in about 5%. Jeune syndrome, or asphyxiating chondrodystrophy, is an extreme form of mixed pectus excavatum/carinatum and is very rare.
TABLE 20-1
Incidence and Etiology of Congenital Chest Wall Anomalies Seen at Children’s Hospital of the King’s Daughters
Many of these deformities are present at birth. Some cases, such as ectopia cordis, are incompatible with life and have rarely been successfully repaired. Chest wall deformities are frequently associated with a systemic weakness of the connective tissues and with poor muscular development of the abdominal region, thorax, and spine. An association with Marfan syndrome, Ehlers–Danlos syndrome, and scoliosis, as well as with omphalocele in the case of bifid sternum, have been identified, all of which complicate the management of these patients (see Table 20-1).
Pectus Excavatum
Pectus excavatum is a depression of the anterior chest wall of variable severity and can usually be characterized as mild, moderate, or severe. The deformity may be localized and deep (‘cup-shaped’; Fig. 20-1A), or diffuse and shallow (‘saucer-shaped’; see Fig. 20-1B), or asymmetric (see Fig. 20-1C). The depth and extent of the depression determine the degree of cardiac and pulmonary compression, which, in turn, determines the degree of physiologic effect. Only one-third of patients referred from our own region had a deformity severe enough to require surgical correction. Even with referral of patients with a severe deformity from other centers, our ratio of operative correction has been only about 60% (Box 20-1).
FIGURE 20-1 (A) Localized or ‘cup-shaped’ pectus excavatum. (B) Diffuse or ‘saucer-shaped deformity. (C) Eccentric deformity.
History
Pectus excavatum was recognized as early as the 16th century. Johan Schenck collected literature on the subject.1 In 1594, Bauhinus described the clinical features of pectus excavatum in a patient who had pulmonary compression with dyspnea and paroxysmal cough, both attributed to the severe pectus excavatum.2 The familial predisposition was first noted by Coulson in 1820, who cited a family of three brothers with pectus excavatum.3 In 1872, Williams described a 17-year-old patient who was born with a pectus excavatum, and whose father and brother also had the condition.4
Numerous other case reports appeared in the 19th century, including a five-case report by Ebstein in 1882 that covered the clinical spectrum of this condition.5 Treatment at that time was limited to ‘fresh air, breathing exercises, aerobic activities, and lateral pressure’.6,7
Thoracic surgery remained ‘forbidden territory’ until the early years of the 20th century. The first attempt at correction was a tentative approach in 1911 by Meyer who removed the second and third costal cartilages on the right side without improvement.8 Sauerbruch, one of the pioneers of thoracic surgery, used a more aggressive approach in 1913 by excising a section of the anterior chest wall, which included the left fifth to ninth costal cartilages as well as a segment of the adjacent sternum.7 Before his operation, the patient was incapacitated by severe dyspnea and palpitations, even at rest, and was unable to work in his father’s watch factory. After recovery, the heart could be seen to pulsate under the muscle flap, but the patient was able to work without dyspnea and was married three years later.
In the 1920s, Sauerbruch performed the first pectus repair that used the bilateral costal cartilage resection and sternal osteotomy technique later popularized by Ravitch.9 He also advocated external traction to hold the sternum in its corrected position for six postoperative weeks. His technique was soon adapted by others in Europe and rapidly gained popularity in the USA. In 1939, Ochsner and DeBakey published their experience with this approach, and reviewed the entire surgical literature on the subject.10 Also in 1939, Lincoln Brown published his experience in two patients and reviewed the literature with particular reference to the etiology of pectus excavatum.11 He was impressed with the theory that short diaphragmatic ligaments and the pull of the diaphragm on the posterior sternum were causative factors.
Ravitch initially subscribed to the short ligament theory as well. As a result, he advocated even more radical mobilization of the sternum, with transection of all sternal attachments, including the intercostal bundles, rectus muscles, diaphragmatic attachments, and excision of the xiphisternum. In 1949, he published his experience with eight patients in which he used this radically extended modification of Sauerbruch’s technique of bilateral cartilage resection and sternal osteotomy, but without external traction.12
The lack of external traction may have led to an increased recurrence of the condition. As a result, Wallgren and Sulamaa introduced the concept of internal support in 1956 by using a slightly curved stainless steel bar that was pushed through the caudal end of the sternum from side to side and bridged the newly created gap between the sternum and ribs.13,14 In 1961, Adkins and Blades modified internal bracing further by passing a straight stainless steel bar behind, rather than through, the sternum.15 This technique was rapidly adapted for patients of all ages.
As early as 1958, Welch and Gross advocated a less radical approach than that of Ravitch.16,17 Welch showed excellent results in 75 patients without dividing all the intercostal bundles or the pectus muscle attachments. However, he still advocated performing the procedure in young patients. Conversely, Pena was very disturbed by the idea of resecting the rib cartilages from very young patients and demonstrated that asphyxiating chondrodystrophy developed in baby rabbits after cartilage resection during their growth phase.18 Later, Haller also reported the risk of acquired asphyxiating chondrodystrophy as well.19 As a result, many surgeons stopped performing open pectus repair in young children and waited until they had reached puberty. They also reduced the amount of cartilage resected and spoke about a ‘modified Ravitch procedure,’ which was really the original Sauerbruch procedure.
In 1997, we published our 10-year experience with a minimally invasive technique that did not utilize cartilage resection or sternal osteotomy, but instead relied on internal bracing made possible by the flexibility and malleability of the costal cartilages.20 The rationale for this technique was based on the three following observations:
1. Malleability of the chest. Children have a soft and malleable chest. In young children, the chest is so soft that even minor respiratory obstruction can cause severe sternal retraction. Trauma rarely causes rib fractures and flail chest because the chest is so soft and malleable.21–23 Thus, the American Heart Association recommends ‘using only two fingers’ when performing cardiac resuscitation in young children and ‘only one hand in older children’ for fear of crushing the heart.
2. Chest reconfiguration. In middle-aged and older adults, a barrel-shaped chest configuration develops in response to chronic obstructive respiratory diseases such as emphysema. If older adults are able to reconfigure the chest wall, children and teenagers should be able to remodel as well, especially with the increased malleability of their anterior chest wall.
3. Bracing. The role of braces and serial casting in successfully correcting skeletal anomalies such as scoliosis, clubfoot, and maxillomandibular malocclusion by orthopedic and orthodontic surgeons is well established. The anterior chest wall, being even more malleable than the previously mentioned skeletal structures, is ideally suited for this type of correction.
Incidence and Etiology
Pectus excavatum occurs in approximately 1 in 1000 children and constitutes 80% of all chest wall deformities in our center (see Table 20-1). However, this is not the case in all countries. In Argentina, pectus carinatum is more common than pectus excavatum.24 Pectus excavatum also is rare in African-Americans and in Africans. A genetic predisposition, already noted in the 19th century, has been found in almost 40% of our patients. We have seen families with three siblings, as well as cousins and other family members, who had a pectus deformity severe enough to require correction. We also have seen patients whose fathers and grandfathers have the deformity. The male-to-female ratio of 4 : 1 in our series of pectus excavatum patients is similar to that of other large series.25 Female patients have an increased risk of associated scoliosis. Inheritance is autosomal dominant, autosomal recessive, X-linked, and multifactorial in different families. 26, 27
Clinical Features
Pectus excavatum is noted in infancy in approximately one-third of patients,25 and usually progresses slowly as the child grows. Because young children have significant cardiac and pulmonary reserve and their chest wall is still very pliable, the majority of young children are asymptomatic. However, as they become older, the deformity becomes more severe and the chest wall becomes more rigid. Eventually, they find that they have difficulty keeping up with their peers when playing aerobic sports. A vicious cycle may develop as patients stop participating in aerobic activities because of their inability to keep up. Subsequently, their exercise capacity diminishes further. The downward spiral is further promoted by the fact that these patients, already embarrassed by their deformity, will avoid situations in which they have to remove their shirts in front of other children, inhibiting participation in school and team activities.
By withdrawing from participation in activities with their peers, they also become depressed, which may affect their schoolwork. Most pectus patients have a typical geriatric or ‘pectus posture’ that includes thoracic kyphosis, forward-sloping shoulders, and a protuberant abdomen (Fig. 20-2). A sedentary ‘couch potato’ lifestyle may aggravate this posture, and the poor posture depresses the sternum even farther. For this reason, we always recommend an aggressive pectus posture exercise and breathing program, both preoperatively and postoperatively.
FIGURE 20-2 Classic pectus posture with thoracic kyphosis, forward-sloping shoulders, and lumbar lordosis.
The earliest complaints are shortness of breath and lack of endurance with exercise. As the deformity progresses, chest pain and palpitations with exercise may develop, giving rise to exercise intolerance. Other symptoms include frequent and prolonged respiratory tract infections, which may lead to symptoms of asthma (Table 20-2).
TABLE 20-2
Presenting of Symptoms Patients Who Have Undergone Operative Correction of Pectus Excavatum at Children’s’ Hospital of the King’s Daughters
Number of patients with echocardiograms = 1148.
Number of patients with mention of cardiac compression (or not) on CT scan = 1450.
Number of patients with mention of cardiac displacement (or not) on CT scan = 1419.
a<80% defined as 2 SD below average of normal population; in a ‘normal’ dataset, only 2.5% of all persons.
A recent study showed that these patients have a poor body image, which has a major impact on their self-worth.28 Therefore, it is important to correct the deformity before it affects their ability to function normally. Just as one would not consider leaving a child with a cleft lip untreated, one should not leave a child with a severe pectus untreated. Both have a physiologic and psychological impact on the patient.
Cardiac and Pulmonary Effects of Pectus Excavatum
A great deal has been written about cardiopulmonary function in patients with pectus excavatum.29 In the last ten years, there has been increasing acknowledgement in the medical community that a severe pectus excavatum has a significant detrimental effect on cardiopulmonary function. Though studies conflict, many older studies treated the condition as either present or absent, with no quantification of the anatomic severity.30,31 Later work demonstrated the effects more clearly, and showed that in a minority of patients there are no deleterious effects on cardiopulmonary function.32 Several factors play a role when testing cardiopulmonary function. These include the severity of the deformity, the inherent physical fitness of the individual patient, the patient’s age, associated conditions, whether the tests are done supine or erect, and whether they are done at rest or during exercise. Recently, a study has shown statistically significant and clinically meaningful improvements in stroke volume, cardiac output, and cardiac index after minimally invasive repair of pectus excavatum.33 Also, an improvement in exercise cardiopulmonary function has been noted as well.
Cardiac effects include decreased cardiac output, mitral valve prolapse, and arrhythmias (see Table 20-2). Compression of the heart results in incomplete filling and decreased stroke volume, which in turn, results in decreased cardiac output.30,31,34,35 Cardiac compression may interfere with normal valve function. Mitral valve prolapse has been found in 13% of our patients and in up to 65% in other series.36,37 Prolapse occurs in only 1% in the normal pediatric population.38 In one study, the mitral prolapse resolved in about half of patients who underwent correction.36 Thus, both mechanical and connective tissue derangements may be involved. Dysrhythmias, including first-degree heart block, right bundle branch block, and Wolff–Parkinson–White syndrome have been found in 16% of patients.39
Pulmonary effects result from poor motion of the depressed part of the chest wall. Normal chest wall motion includes ‘pump handle’ movement of the sternum. The lower sternum moves up and out, like the handle of a mechanical water pump. Physical examination, and now motion capture analysis, show that this motion is almost absent in the depressed area of the pectus excavatum chest. Instead, patients compensate by increased abdominal diaphragmatic breathing. Following correction, the motion is indistinguishable from normal chest wall.40
Pulmonary function testing shows statistically and clinically meaningful diminution in static pulmonary function tests (forced vital capacity, forced expiratory volume in one second, and others) even though most patients do not have any problem with their airways or pulmonary parenchyma (see Table 20-2).35 These values improve after operation. Exercise pulmonary function testing also shows improvement. Stress testing has shown an increase in oxygen consumption for a given exercise when compared with that of normal patients.41 This shows that the work of breathing is increased and explains why they lack endurance.
Evaluation and Indications for Operation
A complete history and physical examination is performed on all patients and includes documenting photographs. Younger patients with a mild to moderate deformity are treated with a posture and exercise program in an attempt to halt the progression and are followed at yearly or longer intervals (Fig. 20-3).
Patients with a severe deformity or those with documented progression also are treated with the exercise and posture program. Additionally, they undergo objective studies to evaluate whether their condition is severe enough to warrant repair. These studies include pulmonary function tests (PFTs), a thoracic computed tomography (CT), or magnetic resonance imaging (MRI) scan, and a cardiac evaluation that includes an electrocardiogram (ECG) and an echocardiogram.
CT scans are very helpful because they clearly show the degree of cardiac compression and displacement, the degree of pulmonary compression and atelectasis, asymmetry of the chest, sternal torsion, compensatory development of a barrel-chest deformity in long-standing deformities, and ossification of the cartilages in patients with previous repairs (Fig. 20-4A, B). They also are used to calculate the CT index, which gives an objective measurement for comparing the severity among patients. The CT index is calculated by dividing the transverse diameter by the anteroposterior diameter (see Fig. 20-4C).42
FIGURE 20-4 (A) CT scan showing cardiac compression and displacement, pulmonary compression, asymmetry of the chest, and sternal torsion. (B) CT scan showing severe pulmonary compression and atelectasis. (C) CT index is calculated by dividing the transverse diameter by the anteroposterior diameter.
Determination of a severe pectus excavatum and the need for repair include two or more of the following criteria: (1) a CT index greater than 3.2; (2) pulmonary function studies that indicate restrictive airway disease; (3) a cardiology evaluation in which compression is causing murmurs, mitral valve prolapse, cardiac displacement, or conduction abnormalities on the echocardiogram or ECG tracings; (4) documentation of progression of the deformity with associated physical symptoms other than isolated concerns of body image; (5) a failed Ravitch procedure; or (6) a failed minimally invasive procedure. With these criteria, only about 60% of patients referred to us are found to have a deformity severe enough to warrant correction.20,43
The age parameters for surgical correction depend on the type of repair selected. Unlike the more invasive procedures (e.g., Ravitch procedure, sternal turnover), there is no interference with growth plates with the minimally invasive approach. Therefore, it can be done at any age, as evidenced by the fact that we have successfully operated on patients from ages 13 months through to 31 years (Fig. 20-5). However, the concern with patients younger than 11 years is that if the procedure is performed at too young an age, many years of subsequent growth remain during which the excavatum can recur.
FIGURE 20-5 Age distribution of the authors’ primary pectus excavatum repairs (n = 1463; median age at surgery 15 years, range 1 to 31 years; data collected from 5/18/1987 through to 1/1/2012).
Our experience suggests that the optimal age for repair is 11 to 14 years. At this age, the patient is prepubertal, the chest is still soft and malleable, there is a quick recovery with a rapid return to normal activities, and results are excellent. After puberty, the flexibility of the chest wall is decreased, sometimes requiring the insertion of two bars, which makes the operation more difficult. It also takes patients longer to recover. However, patients older than 20 years have been uniformly pleased with their results. Several other centers have reported success with patients up to age 44 years.34,44,45
Operative Approaches
Minimally Invasive Pectus Repair
The minimally invasive pectus repair (Fig. 20-6) involves making incisions on each side of the chest and creating a subcutaneous tunnel from the lateral thoracic incision to the top of the pectus ridge on each side. At the top of the ridge, bilateral thoracostomy incisions are bluntly created, and a large introducer is inserted into the chest cavity under thoracoscopic visualization. Very carefully, the pleura and pericardium are dissected off the undersurface of the sternum and the introducer is slowly advanced across the mediastinum and exteriorized through the thoracostomy incision on the contralateral side. When the introducer is in place, the sternum is lifted out of its depressed position by the introducer. Once the sternal depression has been corrected, an umbilical tape is attached to the introducer, and the introducer is slowly withdrawn. The pectus support bar is then attached to the umbilical tape and is slowly guided through the substernal tunnel with its convexity facing posteriorly until it emerges on the contralateral side. All the maneuvers are performed using thoracoscopy to see inside the chest.
FIGURE 20-6 (A) To calculate the length of the pectus bar, measure the distance from right to left midaxillary line and subtract 1–2 cm (1 inch). (B)
