Repair of Pectus Excavatum

Introduction

Pectus excavatum (PE) is a congenital chest wall deformity characterized by a sternal depression, which typically begins at the manubrium and ends toward the xiphoid. Adjacent costal cartilages are displaced as well. The deformity can be symmetric or asymmetric. It is also called a funnel chest or trichterburst.

PE has an incidence of 1 to 8 per 1000 and accounts for 88% of anterior chest wall disorders. It is followed by pectus carinatum with 5%. It is up to 4 times more prevalent in males.

Sometimes PE is associated with connective tissue disease like Marfan syndrome, Ehlers Danlos or osteogenesis imperfecta, or with neuromuscular disease. It is also seen in some genetic disorders like Noonan syndrome and Turner syndrome.

There are a number of hypotheses for what causes PE, but the most widely adopted theory is abnormal rib or cartilage overgrowth. Park et al. evaluated the costal cartilage and rib length between 18 prepubertal patients, 10 years old, with symmetric PE and 18 age-and sex-matched controls without chest wall deformity. They concluded that in patients with symmetric PE, the rib lengths in the patient group were significantly longer than in the control group for the sixth right rib and fourth, fifth, and sixth left ribs, suggesting that abnormal rib overgrowth may be a contributing factor responsible for PE rather than cartilage overgrowth.

Only 22% of PE are present in the first decade of life. In pubertal growth, PE deformity often worsens. A mild PE can progress in 6 to 12 months to a severe type.

At young age, the PE causes no complaints, but as they grow up and become more active, symptoms of shortness of breath on exertion, lack of endurance, and exercise tolerance appears to be problematic.

A frequent reason to seek medical attention is cosmetic concern. A severe PE may have devastating psychologic effects like depression or in rare cases even suicide. Chest pain is also often a complaint. Patients with mild PE have almost normal cardiopulmonary function and the indication is cosmetic. Severe PE produces many more symptoms as listed in Fig. 41.1 .

Treatment Options

Sauerbruch (1920) resected bilateral rib and cartilage with sternal osteotomy requiring external traction to prevent flail chest. This technique has since been abandoned from clinical practice.

In 1949 Ravitch described subperichondral resection of only deformed costal cartilages without entering the chest. After some modifications, the external traction was not needed, but there was a large anterior operative scar. Further modifications resulted in much smaller scars.

Several modifications followed: Robicsek described the use of mesh support to stabilize the sternum. Leonard used a wire behind the sternum that is laterally externalized to be attached to a brace. Lacquet introduced a technique without prosthetic materials. All these procedures are rarely, if at all, used in clinical practice.

In 1997 Nuss introduced the insertion of a preshaped metal bar. His method is also known as the minimal invasive repair of PE (MIRPE). Advantage of this method is less invasive, less blood loss, less nonunion, pseudoarthrosis, floating sternum, less acquired dystrophy, and a shorter surgical time. Some modifications followed. The first modification was the use of thoracoscopy, which allows an extensive view of the surgical field. Before that the surgeon performed a risky blind blunt dissection between the sternum and pericardial sac. Initially thoracoscopy was performed bilaterally, while current practice is limited to unilateral approach. To decrease the incidence of bar flipping. Initially, pericostal rib fixation with a suture was used, and later a stabilizer was attached to the end of the bar. Pilegaard used very short bars in an effort to decrease flipping range.

Surgical alternatives for PE repair include magnet insertion upon the sternum in combination with external traction with a second magnet on a brace. For patients with low physical impact of the PE, the subcutaneous insertion of implantable custom-made prosthesis is an option. A nonsurgical alternative is external sternal suction with a vacuum bell. Physical therapy aiming at improving posture and increasing chest expansion can be offered to patient with mild PE.

Optimal Age for Treatment

At the beginning of PE repair, surgeons believed that operation was best performed early in childhood (before 20 months). Haller described in 1996 a serious complication after a Ravitch procedure: the development of a chest growth disorder or acquired asphyxiating chondrodystrophy. The restricted thoracic cage also restricts lung growth resulting in a reduction of forced vital capacity (FVC) as low as 33% to 55% of predicted. Risk factors are surgery at young age and excessive resection of costal cartilage and growth centers.

Early surgery can also lead to recurrence of the abnormality. In the first publication of Nuss, the median age at surgery was 5 years. Later he recommended to operate before puberty. The current practice is to correct the PE around 14 years. There are few centers that only perform the operation at 3 years; middle-aged patients are only successfully operated. In adult patients aged over 30 years, the addition of open cartilage resection and open sternal osteotomy is more common.

Case Presentation

At the age of 14 years, a healthy young man presented with PE, which was noticeable since a young age. At this time, he weighed 36 kg and his height is 156 cm. He had no physical complaints. Because there was only a 2-cm depression, and the growth spurt had not yet finished, the correction was postponed. At the age of 17 years, he presented again now with symptoms of shortness of breath and chest pain with deep sigh. He also felt embarrassed from his disfiguration. At this stage he was 59 kg and 184 cm. The depression had a depth of 3 cm and was slightly asymmetrically. A photograph of the chest deformity is made ( Fig. 41.2 ). The Haller index was 4 ( Fig. 41.3 ), FVC was 88%, and forced expiratory volume in 1 second (FEV ₁ ) 79% of predicted.

Before the operation a thoracic epidural catheter was placed at T4–T5. The surgery, which will be detailed later in the chapter, was uneventful and a 11-inch bar with two fixation plates was placed. Following extubation, the patient went to the postanesthesia care unit and a few hours later to the ward. On chest radiograph a small bilateral apical pneumothorax (left 1 cm, right 2 cm) was observed ( Fig. 41.4 ). Pain was managed with patient control epidural analgesia (PCEA) ropivacaine/sufentanil. Satisfied with the result, the patient was discharged home on the fifth postoperative day.

Case Management

Preoperative Evaluation and Indications for Surgery

The first step is to assess the severity of the deformity by inspection. The depth of the sternal depression and the asymmetry should be recorded. A depth of more than 2.5 cm is considered moderate to severe deformity. It is common practice for the chest to be imaged by photography to follow-up the progression of the PE or to illustrate the result of a treatment as the pre-surgical image is depicted in Fig. 41.2 .

The practitioner must evaluate the history and progression of the PE and the presence of other symptoms, such as diminished physical activity, fatigue, shortness of breath, or pain. Psychologic and emotional complaints often play an important role to seek for medical help. In addition, associated syndromes or congenital disorders must be considered. Possible allergy to nickel and cobalt (2%) which is the composition of the metal bars must be excluded.

In mild or severe deformity or in cases of cardiorespiratory symptoms, a chest computed tomography (CT) scan is made. The pectus severity index (PSI), also known as the Haller index, is measured at the point of maximal depression and is the ratio between the lateral diameter and the distance between spine and maximal depression as illustrated in Fig. 41.3 . A normal patient has a PSI of less than 2.5 and a severe PE has an PSI of equal to or more than 3.5. The mean Haller CT index, in a study of 1215 Nuss operations, was 5.15 (2.32) (mean standard deviation [SD]). On a CT scan, the position of the heart, lungs, and great vessels can be easily determined. Other chest abnormalities can be observed, (often kyphotic chest) and 10% to 20% will have associated scoliosis.

Cardiac function is evaluated if there is dyspnea or chest pain with exercise or when there are palpitations. Cardiac compression is found in 88% and cardiac displacement in 89% of cases whereas cardiac murmurs occur in 32%. A CT scans and magnetic resonance imaging scans are normally taken in supine position, and cardiac compression is underestimated compared with the upright position particularly with exercises.

Echocardiography (transthoracic or transesophageal) shows displacement of the heart to the left and this can hinders the standard views. Compression of the right ventricle outflow tract may cause a functional systolic murmur. Coln et al. evaluated retrospectively 123 patients, aged 5 to 18 years (average, 13 years) who underwent Nuss pectus repair. Symptoms related to exertion were present in 106 (86%) cases. The mean Haller chest wall index was 4.3 (2.4–10.85). Preoperative echo with exercise revealed cardiac compression in 117 (95%) cases. A mitral valve abnormality was present in 54 (44%) cases. Mitral valve prolapses occurred in 25 and mitral valve regurgitation in 29 cases. Postoperative echo was normal in 100 (93%) of those studied. Seven patients had persistent mitral valve prolapse, one had mild regurgitation. All patients were asymptomatic after surgery.

On electrocardiogram, a right axis deviation and a ST-segment depression can be seen, which reflects the displacement and compression of the heart.

Patients with a severe deformity should undergo pulmonary function testing. Compared with the normal population, patients with PE show a shift toward smaller FVC and FEV ₁ ( Fig. 41.5 ). FVC, FEV ₁ , and FEF _25-75 values were decreased by 15% below predicted value. The most common finding is restrictive pulmonary function, obstructive is less common but also possible and is believed to be caused by less effective respiratory mechanics compared with normal individuals. The relative fixation of the depressed sternum is compensated with increased abdominal wall movement.

A large proportion of patients will not be operated on, and they are referred to a preoperative exercise program that consists of improvement of cardiopulmonary condition, improvement of posture, and increase in chest expansion. Patients have to be re-evaluated within a year following completion of the program.

Donald Nuss summarized the indications for Nuss operation :

If two or more criteria apply:

• Patient is symptomatic, has severe deformity, and has documented progression of the deformity

• Chest CT shows cardiac or pulmonary compression and the CT-index is 3.25 or greater

• Cardiology evaluation demonstrates cardiac compression or displacement with mitral valve prolapse, murmurs, or conduction abnormalities

• Pulmonary function studies show restrictive or obstructive lung disease

• Previous repair has failed

The Surgical Procedure