## 1 Introduction  
Pectus excavation (funnel chest) is the most common chest wall deformity in childhood and adolescence with a prevalence in the literature ranging from 1 in 3400 to 1 in 1000 [1, 2]. Boys are 3 to 5 times more likely to be affected than girls. In most cases, there is an impression on the anterior chest wall that is either present at birth or develops in early childhood. It is caused by a defect in the cartilage of the ribs, involving the sternum. The deformity increases during growth and persists when growth stops [3, 4]. Pectus excavation is often diagnosed in early childhood and usually does not cause symptoms until after puberty or in adulthood. One of the reasons for this is the increased rigidity of the thorax, i.e., the reduced compliance of the chest wall [3]. There is great variability in the extent, depth, and symmetry of the anatomical findings. The deformity may show up as a hole limited to the inferior end of the sternum and the fourth to seventh ribs, but may extend superiorly as far as to the second costal cartilage and peripherally beyond the costochondral junction. The funnel may be symmetric (in about 40%) or asymmetric, with sternal rotation usually to the right [2, 3, 5]. There are also forms that are a mixture of pectus excavation and pectus carinatum, without clearly belonging to either category, as well as even more complex deformities. Patients with pectus excavation show a variety of complaints that do not correlate with the objective extent of the deformity. Breathlessness on exertion, weakness, and early fatigue compared to aged-matched peers are common symptoms, as are inappropriate tachycardia and palpitations on exertion, retrogstral tightness, back pain, and significant psychosocial difficulties [5, 6, 7, 8, 9, 10]. Objective findings that do not consistently correlate with the anatomic severity include restrictive pulmonary function (35-40% of the operated patients),mitral valve prolapse (25% of the patients), or an altered valve annulus and inappropriate tachycardia on exercise. At rest, there is a displacement and rotation of the heart, which can be seen on cross-sectional imaging, as well as reflected in ECG changes, but is usually without clinical significance. Deep deformities may compress the right atrium or ventricle. Gastroesophageal reflux may occasionally occur, and, rarely, swallowing may be impaired [3; 11; 12; 13]. Serious complications such as sudden cardiac arrest as an initial presentation of pectus excavatum are discussed in the literature [14]. In addition to conservative therapy with a suction cup and physiotherapy to improve posture, fitness, and muscle strength, there are several different surgical techniques, many of which have improved over time. The first surgical correction of pectus excavatum was performed by [PERSON] in 1899 with partial sternal resection. [PERSON] developed this technique into an open correction method with extensive subperichondral cartilage resection and non-metallic stabilization [15]: This was--in various modified forms--the standard therapy for decades, especially in the USA. Following the hypothesis that funnel chest is caused by growth disorders such as costal overgrowth, as postulated by [PERSON] and [PERSON] in 1939 [16], this led to an extensive costal cartilage resection sparing the perichondrium in addition to sternal osteotomy [15]. This method, like all other historical techniques, involved very long skin incisions (25-35 cm), extensive soft tissue mobilization, and often a significant blood loss. Subsequently, the trend was almost universally toward minimally invasive surgical techniques, not only for cosmetic reasons but also to reduce the trauma of surgery. [PERSON] took a decisive step forward in 1987 with his well-known Minimally Invasive Repair of Pectus Excavatum (MIRPE) technique. The basic principle is to bend rather than cut.