Pectus excavatum repair using a minimally invasive approach. An apprisal.

Dr L.M.DarlongMS ( AIIMS )Fellow Thoracic Surg ( Korea Univ Med Centre, Seoul )

Email : lmdarlong@gmail.com, drthoracoscopy@g mail.com Phone : 91-9436303717.

Abstract Pectus excavatum (PE) is the most common congenital chest wall deformity and it has physiological, cosmetic and intangible psychosocial implications. Especially with availability of state of the art minimally invasive techniques and rising Indian economy where everyone has the freedom to

feel & live healthy and the right to look good, such patients and their families will be better informed by the medical community and not merely neglect it as a cosmetic defect. Key words: Pectus ex cavatum, Minimally invasive repair of pectus ex cavatum ( MIRPE).

Introduction The most common cong enital chest wall deformity Pectus ex cavatum (PE), or funnel chest occurs in approximately 1 in every 400 to 500 births [1], Males are afflicted approx imately 5 times more often than females althoug h no data is available in the Indian context. The deformity usually occurs as sporadic cases though familial incidence has also been seen through either parent, although not clearly as a recessive trait. It is first recognized by the parents in infancy and it slowly becomes more prominent until full skeletal growth is achieved. This is an important phase during the early ag e as early repair during childhood brings about the best results in terms of morphological correction of the chest wall and thus the development of the mediastinal and pleural cavity contents. In the Indian scenario most of the time medical consultation for such child leaves the majority of patients and their families poorly informed about the limiting physiologic effects of the deformity, or the availability of safe and highly successful options for surg ical correction. This leaves the parents with the impression of it being just a cosmetic deformity with no implications on the cardiopulmonary functions, and it is only during adulthood that the child realizes his defect. Symptoms are infrequent during early childhood, apart from a shy awareness of the abnormality and a typical unwillingness to

ex pose the chest while swimming or taking part in other social or athletic activities. Easy fatigability, shortness of breath with mild ex ercise, and decreased stamina and endurance often become apparent during early adolescence when children become involved in competitive sports. Tachycardia and palpitations are common along with exercise induced wheezing and also an increased frequency of respiratory infections or asthma. The deformity along the sternum displaces the heart into the left chest with pulmonary ex pansion during inspiration restricted resulting in a “restrictive pattern” as noted on pulmonary function tests. The deformity clearly places physiologic restrictions on the patient and thus should not be neglected merely a cosmetic concern. This trend has been mainly due to the nonavailabity of centres or surgeons dealing with this condition and also where available the conventional techniques used for such being too radical with a hig h complication and thus low acceptance. This condition may also be noticed because of other anomalies, like scoliosis (65%), occasionally clubfoot, syndactylism, Marfan syndrome, or Klippel-Feil syndrome. The likely pathogenesis of the deformity results from unbalanced overgrowth in the costochondral reg ions where the involved cartilages are often fused, bizarrely deformed, or rotated. The awareness of this condition and considering it to be a disease

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and not as cosmetic defect will be a g reat boon for such patients, this is especially so

with the introduction of the minimally invasive repair of pectus ex cavatum

EvaluationClinical evaluation involves assessment of the ex ternal morphology along with the CT thorax findings and measurement of the various indices. Various classification are available, and one of them is the morphological classification by Dr Park ( Table 1, Fig 1,2 ) [2] which guides the shaping of the stainless steel bar used in minimally invasive repair. This classification is of great utility in helping shape the bar for asymmetrical defects as the orig inal procedure described by Dr Nuss had limitation for asymmetrical defects. Various indices are used to measure the degree of severity and to evaluate the degree of morpholog ical

correction [3].Hallers CT index is the most widely used index, which is the ratio of the transverse diameter of the rib cage and the anteroposterior distance between the sternum and vertebra (fig3). Normal hallers index is considered upto 2.5 and severity can reach up to 5.5 . Standard pulmonary function tests at rest are either within normal limits or show a mild restrictive defect, however it is difficult to obtain reliable measurements in children’s and limits its use. Electrocardiographic abnormalities are common in PE patients, consisting primarily of right-axis deviation and depressed ST segments, which reflect rotation of the heart within the thorax rather than an intrinsic abnormality.

Minimally invasive approach (MIRPE). The aims of correction of the deformity is to remove the compressive force on the mediastinum and pleural cavity by chest wall remodeling for optimal cardiopulmonary function with the added advantage of improved cosmesis and self confidence of the individual. The optimal age for surg ical correction of the deformity is the earlier the better with optimum at 3 years of ag e. This is due to the bones and cartilage which are more malleable and remodeling is easier and well tolerated with lower recurrences. With increasing age the repair becomes more difficult and more painful because of the rig id bones requiring more force and resulting pain, adults in the age group up to 51 years has been reported by Dr Park who has the largest reported series [4]. Minimally invasive repair was first described by Dr Nuss in 1997 who used a stainless steel bar placed retrosternally to lift the deformed chest wall in the desired chest contour [5]. This procedure has underg one various modification to place the bar retrosternally under vision using thoracoscope or the parks pectoscope ( Perimed Seoul S.Korea ) and also for

correction of asymmetrical defects [4,5,6,7]. The technique described by Dr Park has as spectrum covering repair of symmetric, asymmetric and also adult patients with a problem seeking approach [6]. It involves the placement of stainless steel bar placed retrosternally from one end of the lateral chest wall to the other end through a retrosternal tunnel made under vision using Parks pectoscope, which is very crucial to avoid life threatening cardiac injury in the narrow compressed mediastinum [7]. Following this the bars which have been shaped to exactly duplicate the chest wall morphology with elevation at depressed site and depression at elevated site is introduced in the retrosternal space and fixed at the lateral chest wall leaving behind two small incisions each of 2 cm (fig 4,5). In defects involving long seg ments as in Grand canyon ( Type 2A3 ) or adults two bars are usually placed at the level of the target sites (fig6).Following the procedure pain control is achieved using injectable narcotics initially which can be converted to oral analgesics from day 4 of surgery and may be continued for a period of 2-3 weeks. The bars are removed after 2 years in paediatric cases, 2-3 years in teenager and 3–4 years in adults.

Discussion The management of pectus excavatum is done

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by paediatric surgeon, plastic surgeon, general surgeon and the thoracic surgeons thoug h at times such cases are often referred to orthopaedic surg eon in view of it being a bony and cartilage deformity.The minimally invasive repair of pectus excavtum (MIRPE) as initiated by Dr Nuss in 1997 has found greater acceptance to the surg eons doing the procedure and also higher acceptance among patients. This is truly a minimally invasive procedure unlike the Ravitch, as it does not involve the resection of the cartilages but preservation of the cartilag e for remodeling of the chest wall along the rig id bars contour. As the MIRPE does not involve resection of the cartilage as in other procedure physical activity can be resumed as soon as possible with adequate pain control. However following the resection of the cartilage it takes about 6 months for the ribs to g row again and during this period the chest wall is unstable thus restricting physical activity. Besides this aesthetically the scar of MIRPE is minimal about 2cm only compared to the long scar for

ravitch procedure making it also a minimally access procedure. The complications seen with the procedure are usually pneumothorax, wound infection, pericarditis, pleural and pericardial effusion, bar displacement or dislocation, hemothorax and rarely life threatening cardiac injuries which can be avoided if retrosternal space is created under vision using a thoracoscope or more preferably a pectoscope [7].Recurrence rate less then 5% following bar removal in MIRPE [5] is similar to the ravitch procedure of 2% and thus with surgeons performing more procedure a further reduction is likely. Conclusion With a knowledge of the chest wall anomaly and development of centres in India such patients and their families will be better informed by the medical community and not merely neglected as a cosmetic defects especially with the rising Indian economy where everyone ones to feel healthy and look good.

References1. Boas SR. Skeletal diseases influencing pulmonary function. In: Klieg man RM, et al. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa.: Saunders Elsevier; 2007.2. Park HJ, Lee SY, Lee CS, et al. The Nuss procedure for pectus excavatum: an evolution of techniques and results on 322 patients. Ann Thorac Surg . 2004;77:289–295.3. Lee CS, Park HJ, Lee SY. New computerized tomogram (CT) indices for pectus excavatum: tools for assessing modified techniques for asymmetry in Nuss repair. Chest.2004; 126 (suppl): 777S. 4.Park HJ, Jeong JY, Jo WM, Shin JS, Lee IS, kim KT, Choi YH.Minimally invasive repair

of pectus excavatum: A novel morphology-tailored, patient-specific approach. J Thorac Cardiovasc Surg 2010;139:379-386.5. Nuss D, Kelly RE, Croitoru DP, et al. A 10-year review of a minimally invasive technique for the correction of pectus ex cavatum. J Pediatr Surg. 1998;33:545–552.6. Park HJ. Technical innovations in minimally invasive approach for pectus ex cavatum: a paradigm shift throug h 630 patients. Innovations. 2007;2:25-8.7. Park HJ, Jeong JY, Kim KT, Choi YH. A new videoscopic device to avoid cardiac injury in minimally invasive pectus ex cavatum repair. J Paediatr Surg 2010 ( In Press ).

Table 1

Parks morphological classification of Pectus excavatum.

Morphologic type FeaturesType 1: Symmetric Centre of sternum and depression are in the

midline

1 A: Prototype (Deep,focal) Typical deep focal symmetric sternal depression 1 B: Broad, flat Broad flat symmetric sternal depression

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Type 2: Asymmetric Centre of depression not in the centre of the sternum but found laterally to the left or right

Type 2A:Eccentric Centre of sternum in midline but maximal depression located laterally in cartilage to the left or rig ht

2A1:Focal Deep focal asymmetric depression 2A2:Broad flat Broad flat asymmetric depression 2A3:Long canal, Grand canyon Ex treme form with deep longitudinal groove

from clavicle to lower chest

Type 2 B:Unbalanced Centre of depression in midline but one of the walls of the depression is more severely depressed than other, angles formed by each wall and vertical ax is are different ( alpha < beta )

Type 2 C:Combined Combination of 2A and 2B

Fig 1. Illustration of Parks morphologic

classification of Petus ex cavatum

Fig 2. CT reconstruction of pectus ex cavatum.

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Fig 3. CT measurement of Hallers Index .

Fig 4. Lateral CXR showing steel bar placed retrosternally.

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Fig 5. CT thorax post MIRPE showing corrected deformity and bar on lateral aspect.

Fig 6. CXR showing double bar for g rand canyon type defect.Legends

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Fig 1. Illustration of Parks morphologic classification of Petus ex cavatum.Fig 2. CT reconstruction of pectus ex cavatum.Fig 3. CT measurement of Hallers Index .Fig 4. Lateral CXR showing steel bar placed retrosternally.Fig 5. CT thorax post MIRPE showing corrected deformity and bar on lateral aspect.Fig 6. CXR showing double bar for g rand canyon type defect.

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