Pectus excavatum (PE), funnel chest or sunken chest is the most frequent congenital anomaly of the anterior chest wall. It represents approximately 90 % of these. It is more common in males compared to females with a ratio 4-6:1. The incidence is 1 in 3-400 living born males. It might be discovered in the first living year in around 80 % but in some cases it is first seen at the beginning of the puberty. A family history is occurring in 40 %. Scoliosis is seen in about 20 %. There is also a higher rate of PE in some connective tissue disorders as Marfan and Ehlers-Danlos syndrome.

Leonardo da Vinci was the first to depict it and the first description of PE was done by Bauhinus in 1594. The first attempt to correct it was done by a German surgeon Ludwig Meyer in 1911. The modern era of correction started after 1949 where Ravitch from US published his first paper. This was an open technique with resection of ribs and cartilages. The technique was later modified with smaller incisions, preserving of the perichondrium and introduction of supporting material under the sternum to retain the position. This technique was the gold standard until Nuss published his technique of minimal invasive repair in 1998. Other methods have also been used as reversing the sternum and treatment with braces.

Indication

In many years it was thought that PE was only a cosmetic problem for the patients and the cosmetic complains are stated as indication in around 90 % of the published papers in this field. Several papers studying the quality of life in patients with PE have shown a significant better quality of life after correction with higher self-esteem. More of these studies have also shown that patients after treatment feel that they have a better physical performance. More than 60 % have symptoms like exercise intolerance, lack of endurance and shortness of breat].

It is obvious from CT-scans that the heart is moved more to the left in PE-patients because of the pressure from the sternum and it is also seen in many patients that the right side of the heart is compressed. This does not influence on the cardiac performance at rest but restricts the filling of the heart under physical activity. The cardiac performance is found to be reduced about 20 % in adolescent age 14-17 years with a PE, but after treatment it becomes equal to normal control]. In adults it has too been shown that the cardiac performance is significant raised after correction by the modified Ravitch.

In most cases patients with PE have a normal lung function but in the lower area. The reduced lung function has a restrictive picture. Studies have shown decreased movement of the chest in PE patients which change to better movement after correction.

Some surgeons use the Haller index as an indication. The Haller index is the ratio between the internal diameter of the chest at the level of the deepest point of the excavation and the distance from the backside of the sternum to the anterior part of the spine. If this is > 3,25 , there might be indication for treatment. The index is dependent of the chest shape, because the same excavation seen from outside may give different indexes depending on if the chest is barrel shaped or more flat.

There is no evidence for the optimal age for performing the procedure. In the eastern part of the world surgeons often correct the patients in the age group 2-6 years. It is difficult to understand that so young children are complaining about the cosmetic and they do probably not have any symptoms. Nuss has seen that there is a trend to see more recurrences if the bar is removed before the puberty where the growth spurt starts. I would not treat a patient before the age of 11 years. It is important that the child understand what is going on and what one might expect of pain concerning the correction. My optimal age is 11-13 years, but many girls are even older so they have had a demarcation of the breasts which allow to place the incisions in the groove between the breast and the chest wall. The upper limit for doing the Nuss procedure is not defined. When the procedure was published it was said that only children and adolescents were candidates for this treatment, but with the growing experience even patients more than 60 years have been corrected with good results and few complications.

Preoperative evaluation

Patients are seen for a clinical examination. An x-ray of the chest in the AP- and the lateral view is often sufficient. You may from this x-ray calculate a Haller index if you want, even it is not as exact as from a CT-scan. Doing only an x-ray also reduces the radiation to the patient. If there is suspicion to the internal organs in the chest, it is necessary with a CT-scan of the chest and especially if Marfan is suspected, also an echocardiography has to be done.

The patient should be informed about the expected result. This means that the excavated area disappears but if there are flaired ribs they will often remain.

Technique

The original technique prescribed a bar length going from one mid-axillary line to the other. It is difficult to understand why the bar should be so long. The ends of the bar would only be parallel to the lateral chest wall and therefore not deliver any force from the pressure of the sternum. Placing the stabilizer(s) at the end(s) would really not secure the bar against rotation.

Today more surgeons are using a shorter bar as proposed by Pilegaard. A short bar is easier to place. The median length of bars is in 840 corrected patients 10”. The bar might be guided in a better way through the chest and is also easier to remove. The stabilizer can be placed very close to the hinge point which gives a very stable situation, so you do not need additional sutures around the bar and the rib.

How many bars which is needed in the patient is dependent of the depth of the excavation and the age of the patient. It is better to put two bars in a patient instead of abstain one. Two bars may in many cases be inserted through the same incisions especially in females, where the skin of the breasts often are more moveable. More bars will probably decrease the pain because of delivering the pressure to a bigger surface. In very few cases even 3 bars may be needed to get a good correctio).

One bar should normally support the deepest point. If the PE is very long like a grand canyon type a bar is often placed at the level of the nipples. In such a case a periareolar incision around the nipple on the left side makes it easier to put the stabilizer on.  If the PE is very low and the deepest point is below the sternum you should use two bars where the upper one support the sternum and the lower one is under the deepest point. The deepest point is sometimes between two levels of intercostal spaces. Here it might be a good idea to use an oblique approach. If the excavation is very deep it is a good idea to place the first introducer higher than the deepest point as this will work like a crane and facilitate to go under the deepest point with the next introducer. Different types of crane systems might also be used.

The procedure is done in general anaesthesia. All patients should in my opinion have an epidural catheter for postoperative pain treatment. This stays for two days. The patient is intubated with a single lumen tube, and only if you expect problems inside the chest cavity because of previous intervention or infections you need a double lumen tube. You may use CO₂ gas to get a better view in the chest cavity, but it is often not necessary in my experience. The  patient is located to the right on the table with the arm in front of the head . The thoracoscope is inserted through the right lateral chest wall at the level of the nipple. This gives you free movement of the scope and no problems to follow a very low bar.

The deepest point is identified, and the intercostal spaces which is related to this is marked just medially to the highest point. You may check this by putting a finger where you have marked and push, you can then see through the scope if it is the correct point related to the deepest point. A template is shaped to the wanted shape of the chest and even with some overcorrection, because the bar will flattened in some way by the pressure from the elevated sternum. The bar is bended in the same way. The tunnel under the sternum is normally done by one of the introducers and the large one will in most cases be the one you should use. If there previously has been surgery inside the chest cavity and adhesions are found, they should all been cut and the tunnel done by blunt dissection using a long instrument with a peanut. If it is a long excavation and two bars are needed, it is often an advantage to place both the introducers at first and then replace one after the other with a bar.

The bar is guided by a tape or a suture under the sternum and inserted like a U and turned 180^o. Generally the stabilizer is located on the left side. The bar is placed asymmetric on the chest, so the end with no stabilizer too has a base of two ribs . No additional sutures are necessary. The position of the stabilizer to the left might be a good idea to avoid compression of the heart if the end of the bar without a stabilizer occasionally should drop into the chest.

The air inside the chest is exsufflated by a thin tube through the port to the scope and then the tube is removed.

The bar(s) is generally removed after 3 years.

Complications

The complication rate should be low. The infection rate is about 1-2 %. The risk of bleeding is < 1 %. The rate of rotation or dislocation is approximately 1 %. Doing this kind of surgery you need to be able open the chest by a sternotomy if you get lesions to the heart or there should be access to cardiac surgeons who can help if such a complication should happen. The number of procedures which is needed to keep complication rate low and have good results are not known, but 2-4 cases a month might be an acceptable number.

Even you exsufflate the air after surgery you will see that about 50 % has a small pneumothorax. It is generally not necessary to treat this because it would be absorbed during few days. Even the pneumothorax is bigger, observation might be done if the patient has no symptoms.

Removal of the bar(s)

This is done 3 years after insertion as a day surgery procedure in most cases. The patient comes to the hospital in the morning prepared for general anaesthesia. The bar is removed and the patient may be discharged later in the day time without further control.

The recurrence rate is low around 1 %.

Excerpt from

H. Pilegaard in “Thoracic Surgery in Children and Adolescents”, Claus Petersen, Benno M. Ure (Eds.), 2016 Walter de Gruyter GmbH, Berlin/Boston