(A) Type I to IV, by Collett and Edwards (1949). Of note, type IV is no longer considered a variant of truncus arteriosus, but rather it is categorized as pulmonary atresia.
(B) Types A1 to A4, by Van Praagh and Van Praagh (1965).
Reproduced with permission from: Cabalka AK, Edwards WD, Dearani JA. Truncus arteriosus. In: Heart Disease in Infants, Children, and Adolescents Including the Fetus and Young Adult, 7
th ed, Allen HD, Shaddy RE, Driscoll DJ, Feltes TF (Eds), Lippincott Williams & Wilkins, Philadelphia 2007. Copyright © 2007 Lippincott Williams & Wilkins.
www.lww.com.