Cyanotic Attackをくり返すファロー氏四徴症に対するIsoproterenolおよびPropranolol投与の及ぼす影響

Hemodynamic Effects of Isoproterenol and Propranolol in Patients with Tetralogy of Fallot accompanied by Repeated Cyanotic Attack

緒言

　ファロー氏四微症や類似の血行動態をもつ疾患患者の一部に発作性に呼吸困難，チアノーゼの増強をきたす，いわゆるcyanotic attackを伴うもののあることはよく知られている。このcyanotic attackはさらに失神発作や痙攣などの中枢神経症状を起こし，悪くすれば時に死に至らしめる。この点臨床上重要な症状の一つである。しかしその発生機序に関し種々の考察がなされているが，いまだ明確にはされていない。近年このcyanotic　attackにpronethalolやpropranololなどのβ—reccptorのblockerが治療効果を持つことが確かめられてきた^5）〜9）。また最近Cumming^10）はファロー氏四徴症にβ—receptorのstimulant （isoproterenol）とblo—cker （propranolol）の両者を用い血行動態の検索を行ない本症のcyanotic attackが右室流出路のspasmにより急激な肺血流量の減少，右—左短路の増加により発生するとの考えを支持する成績を発表した。われわれもcyanotic attackをくり返す重篤なファロー氏四徴症患者2例に同様の検索を行なったのでその成績を報告し，本症のcyanotic attackのmechanismに関し多少考察を加えてみたい。

The hemodynamic effects of isoproterenol (beta-adrenergic stimulant) and propranolol (beta-adrenergic blockade) were studied on two patients with tetralogy of Fallot, having repeated deep cyanotic attack.

In right ventriculogram all of them had slight degree of right ventricular outflow obstruction, not so narrow pulmonary artery and ventricular septal defect beneath the crista supraventricularis.

By the administration of isoproterenol, the clinical symptoms same with that of cyanoticattack were developed. Then the increase of right to left shunt and degree of right ventricular outflow obstruction, the decrease of pulmonary blood flow and arterial oxygen saturation were observed.

Propranolol evidently released cyanosis and developed the hemodynamic state contrary to the above mentioned effects of isoproterenol. Also this drug was clinically useful in pre-venting and treating cyanotic attack in all of these patients.

These findings and results may suggest that the functional increase of right ventri-cular outflow obstruction is closely related with the mechanism of cyanotic attack in tetralogy of Fallot.