The Surgical approach to Pectus Excavatum: Present and Future insights

2011/2012 José Miguel Alves Lobato The Surgical approach to Pectus Excavatum: Present and Future insights Março, 2012 Mestrado Integrado em Medicina Área: Cirurgia Pediátrica Trabalho efetuado sob a Orientação de: Prof. Dr. Tiago Henriques-Coelho Trabalho organizado de acordo com as normas da revista: European Journal of Pediatric Surgery José Miguel Alves Lobato The Surgical approach to Pectus Excavatum: Present and Future insights Março, 2012 1 Agradecimentos Ao Prof. Dr. Tiago Henriques-Coelho, meu orientador, pela disponibilidade que demonstrou para ouvir um aluno de 5ºano com uma proposta e encetar os esforços para que uma pequena ideia possa quiçá crescer e dar frutos mais tarde. Aos Professores, que mesmo órfãos do título, foram-no integralmente neste meu longo percurso académico, apoiando-me e fazendo-me crescer passo a passo, em especial a Prof. Dr. Augusta Silveira. À minha Mãe e ao meu Pai pela força e crença que sempre demonstraram em mim, com um beijo muito sentido à minha Mãe por me fazer questionar tudo e um especial abraço ao meu Pai por sempre me ter tentado mostrar que quando pomos um pé na Lua devemos ter Marte no horizonte. À Marta por ser quem é e pela força que me transmite diariamente, nunca esmorecendo e sendo peça fundamental neste meu percurso na Faculdade de Medicina. Finalmente à minha Avó, que certamente reluziria um orgulho que empalideceria o sol ao me ver Médico formado, adorava que me pudesses ver agora. 2 Resumo Pectus Excavatum é uma patologia prevalente em idade pediátrica, pode afectar até 1 em cada 400 indivíduos e levar a disfunção cardíaca e pulmonar. Esta doença presume-se ser de origem genética, levando a um crescimento excessivo de estruturas cartilaginosas esternais. O gene responsável por este fenótipo ainda é desconhecido. Esta patologia caracteriza-se habitualmente por diminuição na capacidade de exercício assim como perda de auto-estima com consequências tardias no normal desenvolvimento social da criança. Uma abordagem cirúrgica pode minimizar as complicações no desenvolvimento psico-social e fisiológico da criança. As cirurgias mais utilizadas são os procedimentos de Ravitch e de Nuss. O procedimento de Ravitch consiste numa cirurgia com exposição de estruturas ósseas e correção local de defeitos costocondrais. O procedimento de Nuss é minimamente invasivo e recorre a uma barra pré-formada que é colocada na cavidade torácica com auxílio de fibroscopia. Neste artigo os autores sumarizam o que é correntemente empregue para corrigir esta patologia de forma cirúrgica e não-cirúrgica assim como procedimentos de diagnóstico utilizados para categorizar a mesma. Também avaliamos as principais diferenças entre ambas as técnicas cirúrgicas enfatizando as vantagens e desvantagens entre ambas. De olhos postos no futuro, os autores também estabelecem o que consideram ser o primeiro modelo experimental para Pectus Excavatum assim como referem pela primeira vez uma possível nova abordagem cirúrgica para a correcção desta deformidade. 3 The Surgical Approach to Pectus Excavatum: Present and Future insights José Miguel A. Lobato Faculty of Medicine of the University of Oporto Al. Prof. Hernâni Monteiro 4200 – 319 Porto, Portugal [email protected] Address of the corresponding author: José Miguel A. Lobato Faculty of Medicine of the University of Oporto Al. Prof. Hernâni Monteiro 4200 – 319 Porto, Portugal [email protected] 4 Abstract Pectus Excavatum is a prevalent pathology in the pediatric age group, it can afflict up to 1 in 400 individuals and lead to pulmonar and cardiac dysfunction. This disease appears to have a genetic origin, causing an excessive growth of cartilaginous sternal structure. The gene responsible for this phenotype is not yet known. This pathology is commonly characterized by diminished exercise capacity as well as a lower self-esteem with later consequences in the child’s normal social development. A surgical approach can minimize the psycho-social developmental and physiological distress caused by this disease. The most frequently used surgical approaches are the Ravitch and Nuss procedures. The Ravitch procedure consists of an open chest surgery with exposition local correction of the costochondral defects. The Nuss procedure is minimally invasive and resorts to a pre-formed bar that is placed inside the thorax using fibroscopy. In this article, the authors summarize what is currently employed to surgically and non-surgically correct this pathology, as well as diagnostic procedures utilized to categorize the disease. We also assess the main differences between both surgical techniques emphasizing their advantages and disadvantages regarding each other. Looking towards the future, the authors also establish what they consider to be the first experimental model for pectus excavatum as well as referring for the first time a putative new approach to the surgical correction of this illness. Key words: Pectus Excavatum; Experimental model; Ravitch procedure; Nuss Procedure 5 Introduction Pectus Excavatum (PE) is a major congenital anomaly which affects mostly men over women on a 5:1 ratio and occurs in 1:400 childbirths. It consists of changes in the development of the costal arches and the sternum which cause sternal depression, often compressing mediastinic structures and usually involving the lower sternum and costal cartilages. It is present at birth but most frequently manifests itself during early childhood, the severity of the deformity is usually exacerbated when puberty ends. Cardiac and pulmonary compressions are responsible for physiologic and structural changes. [1-3] Psychosocial issues can arise from this pathology and its exacerbation occurs in the adolescent. Some surgical procedures have been successfully applied to the correction of this pathology. The current trend is Nuss procedure that has an obvious esthetical advantage compared to Ravitch procedure. The purpose of this study is to review the main treatment options for PE, focus on the advantages and disadvantages, as well as propose an experimental protocol for an alternative approach to this pathology. 12 Conclusion Currently there are two well documented and well established surgical approaches to PE. Both the Ravitch and the Nuss procedure have their advantages and disadvantages. If the decision is on the patient’s side, Nuss procedure is preferred probably because of the final aesthetic results without an anterior chest scar. Other alternatives such as Vacuum bell appear to be limited in applicability whilst the magnetic mini-mover is just now showing its first results undergoing clinical trials. Proposal for an experimental protocol Pectus Excavatum is an interesting area of research. There is no wellestablished animal model. There is a mouse strain for Marfan disease that carries PE and the work of Haje et al which document a surgical animal model for PE. [31] - Experimental design Young Wistar rats will be weaned at 21 days of age. At the 30th day of life they will be anesthetized and subjected to a midline longitudinal incision in the sternum with division of pectoral muscles and subsequent exposition of the costal and sternal cartilages. The anterior portion of the sternal growth plate will be destroyed by electrocoagulation (Haje et al). The incision will be closed with sutures through the pectoral muscles and skin. The control group will consist of animals without any surgical procedure. At 90 days of age the surviving rats will be radiographically analyzed to compare the length and curvature of the sternum. It is expected that the Group submitted to surgical procedure will have acquired some form of Pectus deformity. The animals with induced PE will be submitted to the placement of orthodontic thermolabile wires across 4 adjoining ribs and its contralateral counterparts. The 13 fixation of these wires will resort to microimplants that will attach the metal arches to the osseous structures. One implant will be placed on the costal angle on the rib in its anterior surface and another one on the contralateral rib in the exact same place. The other two implants which sustain each arch will be fixated to the sternum. The arch for each set of contralateral ribs will thus be fixated by 4 implants. A Sham group will undergo the exact same surgical procedure but the arches will not be attached to the bone and will remain subcutaneously under the pectoral muscles. Radiographic evaluation will be assessed at 120 and 150 days of age in both groups and the animals will be euthanized and target of assessment both by imaging and histologically at 180 days of age. 14 References 1. Williams, A.M. and D.C. Crabbe, Pectus deformities of the anterior chest wall. Paediatr Respir Rev, 2003. 4(3): p. 237-42. 2. Coskun, Z.K., et al., The prevalence and effects of Pectus Excavatum and Pectus Carinatum on the respiratory function in children between 7-14 years old. Indian J Pediatr, 2010. 77(9): p. 1017-9. 3. Westphal, F.L., et al., Prevalence of pectus carinatum and pectus excavatum in students in the city of Manaus, Brazil. J Bras Pneumol, 2009. 35(3): p. 221-6. 4. Robicsek, F., L.T. Watts, and A.A. Fokin, Surgical repair of pectus excavatum and carinatum. Semin Thorac Cardiovasc Surg, 2009. 21(1): p. 64-75. 5. Kelly, R.E., Jr., Pectus excavatum: historical background, clinical picture, preoperative evaluation and criteria for operation. 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Redlinger, R.E., Jr., et al., One hundred patients with recurrent pectus excavatum repaired via the minimally invasive Nuss technique--effective in most regardless of initial operative approach. J Pediatr Surg, 2011. 46(6): p. 1177-81. 29. Jo, W.M., et al., Surgical treatment for pectus excavatum. J Korean Med Sci, 2003. 18(3): p. 360-4. 30. Luu, T.D., et al., Surgery for recurrent pectus deformities. Ann Thorac Surg, 2009. 88(5): p. 1627-31. 31. Haje, S.A., et al., Disorders in the sternal growth and pectus deformities: an experimental model and clinical correlation. ACTA ORTOP BRAS 1998. 6(2)(ABR/JUN). 17 European Journal of Pediatric Surgery: Instruction for Authors European Journal of Pediatric Surgery is a broad-based international journal, appearing six times per year, publishing vital developments in pediatric surgery through original articles, reviews, case reports, case galleries, special reports, abstracts of the literature and meeting announcements. 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