How I do .... a Pectus Repair


Aetiology
Syndromes

Natural history and timing of surgery
Indications for operation
Operation
Other procedures



Further reading:
Surgical Treatment of Anterior Chest Wall deformities, Chest Surgery Clinics of North America, May 2000, 261 - 276

Aetiology

The actual cause of pectus deformities is unknown. The usual explanation, for which there is some experimental evidence, is that there is overgrowth of the costal cartilages resulting in either protrusion or intrusion of the sternal elements.

Syndromes
Pectus excavatum (funnel chest)
Pectus excavatum occurs when the cartilage overgrowth results in the sternal manubrium being forced back towards the vertebrae. It is more common in males and frequently runs in families.

Pectus excavatum occurs when the cartilage overgrowth results in the sternal manubrium being forced back towards the vertebrae. It is more common in males and frequently runs in families.

In severe cases the xiphisternum virtually touches the vertebrae, displacing the heart laterally, usually to the left. The excavatum deformity behaves as though there are attachments to the tendinous diaphragm and even the vertebrae. As the child grows around this attachment, the sternum and cartilages are drawn in. Eventually the ends of the ribs are drawn in and the chest cavity becomes elongated and flattened. The clavicular heads are drawn in when the deformity is severe. The appearance is of a tall thin male with a flattened elongated chest and a concavity at the lower end of the manubrium.

Patients are often referred because of their associated asthma, the deformity being blamed for the respiratory effects. There is no evidence that it does. Others fear pressure on the heart. Again the evidence is rather poor for any cardiac compromise, many a pectus patient being well able to run a marathon. There is some evidence that severe deformities may impede right atrial filling at maximal exertion. As the heart is rotated to the left in severe deformities, right axis deviation and tall P waves can be seen in lead II.

Pectus carinatum (pigeon chest)
Pectus carinatum is thought to have a similar aetiology to excavatum. However, there is no similarity to the diaphragmatic adhesion. As parents do not fear cardiac compression minor deformities are often well tolerated. As breast development progresses normally girls often do not mind a mild carinatum deformity.

Mixed excavatum/carinatum
To be truthful virtually all deformities are mixed to a degree with some rotation of the sternum. It should be expected and not regarded as a difficulty. Frequently the rotation is so slight it is best left alone. More extensive rotation will need to be corrected with imaginative osteotomies and wedges.

Kypho-scoliosis associated
Pectus-like chest wall deformities often accompany Kypho-scoliosis. The deformity is usually unilateral and carinatum in nature. It is usually secondary to the vertebral rotation and is a rib deformity rather than a cartilage deformity. The deformity is exacerbated by the need for the lung to find some volume in which to operate. Therefore, any attempt to correct the deformity tends to fail as the lung re-expands and pushes the chest wall back out. To correct the deformity, rib osteotomies would need to be performed. This is virtually impossible to perform in flat bones.

Poland’s syndrome
Poland’s syndrome is a more extensive syndrome of defects of the chest wall. It includes loss of pectoralis major or minor muscles, hypogenesis or absence of the breast, absence of mammary and axilary hair, absence of costal cartilages and failure of the ribs to grow. Correction involves a combined procedure with the thoracic surgeon re-construcing the chest wall while the plastic surgeon performs an augmentation mammoplasty with latissimus muscle myocutaneous flap. The procedure must therefore be performed when growth is complete.

Agenesis of the sternum
Various degrees of sternal agenesis can occur with varying degrees of cardiac herniation. It is a rare congenital condition associated with craniofacial haemangiomata and omphalocele. It should be corrected in the neonatal period when the two halves of the sternum can usually be sutured together. Usually there are residual cartilaginous sternal bars connecting the rib ends.

In older children it may be necessary to perform slide chondroplasty accompanied by longitudinal osteotomies of the sternal bars to bring the two halves together. Skin cover may require omental or pectoral flaps. (See Cleft sternum and Sternal Foramen. Alexander A Forkin. In Surgical Treatment of Anterior Chest Wall deformities, Chest Surgery Clinics of North America, May 2000, 261 - 276)

Natural history and timing of surgery
If left unoperated the deformity increases in size, most markedly in the years of the pubertal growth spurt. As it becomes more severe, the rib ends are drawn in and the deformity of the ribs becomes permanent if correction is not performed before growth finishes. Many clinicians leave surgery “till growth has stopped”, hoping they will grow out of the deformity or that muscle growth will obscure it. Neither is the case in truth. At this stage the rib deformity cannot be corrected and the results cannot be satisfactory.

Young children are hardly aware of the diagnosis and have no interest in having it corrected. The easily embarrassed teenager however, will avoid taking his shirt off and will avoid swimming, changing in front of his mates for football and so on. In his late teens the self-conscious youth will be embarrassed by his appearance when dealing with the fairer sex.

There is no need to operate on the pre-school child when he is exposed to all the paediatric anaesthetic risks. I usually operate at about 8 years of age when anaesthesia is safer, there is plenty of time for the deformed ribs to refashion themselves and a few weeks off school will not affect his academic progress. At this stage the deformity is mild and he is usually not worried by the condition. However, at this age he is still not conscious of the deformity, though his parents may be, and it will be difficult to convince him that, by the time he is conscious of it (at age 15) it will be too late to get a good result. This then is the dilemma facing the advising surgeon.

Indications for operation
The indication for the operation is cosmesis. It is a cosmetic operation only. Concerns about asthma and pressure on the heart are unfounded.

However cosmesis is important to the full development of a child. I know I am exposing my Australian sport-loving bias when I say it is important for a young man to go swimming and to play football without worrying about his appearance. If my operation allows him to fully develop socially and in sport, I feel it is worthwhile. One must of course remember that this is an operation with all its attendant risks and it is being performed purely for cosmetic reasons.

Having said that, where there is a severe deformity at a relatively young age I do suggest strongly to the parents that they should consider surgery. While there is little evidence for it I find it hard not to imagine some restriction of cardiac filling on exertion when there is severe displacement of the heart.

Operation

The operation I perform is a modification of the sub-perichondrial excision operation popularised by Ravitch. The sternum is radically mobilised and only an absorbable PDS suture is left to support it.

The operation steps are the same for an excavatum or carinatum defect with only the final osteotomies being different. Even for unilateral deformities I usually find it necessary to perform bilateral dissections in order to make the two sides equal. There are exceptions to this where leaving the normal side intact acts as a good scaffold for the reconstructed side.

Anaesthesia, position and preparation
General anaesthesia with muscle relaxation is used. Single lumen endotracheal intubation is used, there being no indication for single lung ventilation. Intravenous access and both invasive and non invasive blood pressure monitoring should be in place. Blood group and save should be obtained but cross match should not be required. Some anaesthetists favour epidural analgesia placed prior to surgery. Because of the difficulty anaesthetising to the level of the second costal cartilage, others prefer PCAS and systemic analgesia.

The patient is placed supine. A small sandbag may be placed between the scapulae.

The skin is prepared from the chin to below the umbilicus. Draping should leave the sternal notch, nipples and umbilicus exposed to allow planning of the incision and extent of the repair.

Equipment
Special instrument sets are available for chest wall reconstruction, particularly for paediatric use. As with most procedures I try to keep to standard instruments.