Pectus excavatum

Japanese: 漏斗胸

(1) Pectus excavatum
Definition and Concept Pectus excavatum is a disease in which the sternum, the costal cartilage attached to it, and the ribs are depressed. It is thought that the main cause is an abnormality in the costal cartilage, but there is no clear proof. It is known that it often occurs within families and is often associated with Marfan syndrome, and genetic predisposition is also thought to be involved. Another cause is thought to be a depression in the thorax due to excessive negative pressure in the thorax during inspiration caused by tonsillar hypertrophy or upper airway stenosis such as adenoids. The incidence of pectus excavatum is thought to be about 0.5%, with a male-female ratio of 3-4:1, and it is more common in men. The degree of depression in the thorax varies, and usually the central anterior chest is depressed, but in some cases the depression is asymmetric with a deviation to the right, and in some cases it is deviated to the left, although this is rare. The depression is often noticed from birth to 1 year of age, and increases with growth. After the age of 10, the depression deviates to the right, and about half of children in junior high school and above are asymmetric. In women, it also affects breast development, posing a cosmetic problem.
Pathogenesis and clinical symptoms: Respiratory function tests reveal obstructive respiratory dysfunction in accordance with the deformation of the thorax, but subjective chest symptoms are rare. Up until school age, children are prone to developing bronchitis along with colds, and narrowed bronchi can cause asthma-like symptoms. The deformation of the thorax causes the heart to shift to the left, compressing it anteriorly and posteriorly (Figure 7-17-1), and electrocardiograms reveal incomplete right bundle branch block and negative conversion of P waves in V1. Abnormalities in valve formation are also common, and it is known that valvular disease, especially mitral valve prolapse, is common.
Treatment: In infancy, it is difficult to distinguish from pseudopectus excavatum, so the treatment is usually performed at age 3 or older. Since surgery is easier when the costal cartilage is soft and mobile, the optimal age is around 10 years old. The purpose is not to improve cardiopulmonary function, but to improve cosmetic appearance. Surgery has traditionally been performed using sternal elevation and sternal flipping. The sternal elevation method involves removing the deformed costal cartilage, resecting the sternum, and then resuture to elevate the sternum, as reported by Ravitch et al. in 1949. This is the basic method, and has been improved with several modifications, making it a widely used standard surgical procedure. In adults with stiff sternum and ribs that have reduced mobility, sternal flipping is performed. The depressed sternum and costal cartilage are removed as a single unit, and a shallow incision is made to flatten the sternum, after which it is flipped and resutured.
A new minimally invasive surgery was reported by Nuss et al. in 1998. With the assistance of a thoracoscope, a metal bar is inserted under the sternum to elevate the depressed sternum. As there is no need to remove the sternum or costal cartilage, only a small incision is made on the side of the chest, the operation time is short, and there is little blood loss. As a result, many facilities have adopted this procedure, and the number of surgeries using this procedure is increasing in Japan as well. Complications include cardiac damage during insertion of the bar, infection caused by the bar, and dislocation of the bar. The inserted bar is removed after approximately two years. [Suya Akihisa and Isobe Takeshi]

Source : Internal Medicine, 10th Edition About Internal Medicine, 10th Edition Information

Japanese:

（1）漏斗胸（pectus excavatum）
定義・概念
　漏斗胸は胸骨とそれに付着する肋軟骨および肋骨が陥凹する疾患で，肋軟骨の異常がおもな原因と考えられているが，はっきりとした証明はされていない．家族内発生やMarfan症候群での合併が多いことも知られており，遺伝的素因の関与も考えられている．また扁桃肥大や，アデノイドなどの上気道狭窄により吸気時の過剰な胸郭陰圧負荷による胸郭の陥凹も原因の1つとして考えられている．　漏斗胸の発生率は0.5％程度と考えられ，男女比は3～4：1で男性に多い．胸郭の陥凹の程度はさまざまであり，通常は前胸部中央が陥凹しているが，陥凹が右側に偏倚し非対称性になるものもみられ，さらに頻度は低いが左側に偏倚するものもある．陥凹は出生時から1歳までに気づかれることが多く，成長とともに増強する．10歳をこえると陥凹は右側に偏倚していき，中学生以上では約半数が非対称性となる．女性では乳房の発育にも影響し，美容上の問題となる．
病態・臨床症状
　呼吸機能検査では，胸郭の変形に応じた閉塞性呼吸機能障害を認めるが，胸部の自覚症状を伴うことは少ない．学童期までは感冒に気管支炎を併発しやすく，狭窄した気管支により喘息様の症状を呈することがある．　胸郭の変形により心臓の位置も左に偏倚し，前後に圧排変形するため（図7-17-1），心電図では不完全右脚ブロックやV1でP波の陰転化などを認める．弁形成の異常も伴いやすく，弁膜症，特に僧房弁逸脱症の合併が多いことが知られている．
治療
　乳児期では偽性漏斗胸様陥凹との区別がつきにくいため通常は3歳以上で，また肋軟骨が軟らかく可動性に富むほうが手術が容易なため10歳程度までが至適年齢となる．心肺機能の改善が目的ではなく，美容的改善が目的となる．　手術は従来，胸骨拳上法と胸骨翻転術が行われてきた．胸骨拳上法は変形した肋軟骨を切除し，胸骨を喫状切除後再縫合し胸骨を拳上させる方法で1949年にRavitchらにより報告された．これを基本法とし，いくつかの変法による改良のもと広く標準的な術式として行われている．胸骨や肋骨が硬く，可動性の低下した成人例では胸骨翻転術が行われる．陥凹した胸骨と肋軟骨を一塊として切除し，浅い切開を入れ扁平に形成したのちに，翻転し再縫合する．
　1998年Nussらにより新しい低侵襲手術が報告された．胸腔鏡補助下に胸骨裏面に金属製のバーを挿入し陥凹した胸骨を拳上する方法で，胸骨や肋軟骨の切除が不要なため，創部は側胸部の小さな傷のみで，手術時間も短く，出血量も少ない．そのため，多くの施設が取り入れ，わが国でもこの術式での手術件数が増えている．合併症としてはバー挿入の際の心臓損傷，バーによる感染，バーのずれなどがある．挿入したバーは約2年後に抜去する．［須谷顕尚・礒部　威］

出典　内科学第10版内科学第10版について　情報

<<: Reading - Roudoku

>>: Labour force participation rate