1. The conduction system in hearts with pulmonary atresia and intact ventricular septum 
Aneel Ansari, MBBS, Diane Goltz, MD, Karen Patricia McCarthy, BS, Andrew Cook, BS, Siew Yen Ho, PhD 
The Annals of Thoracic Surgery 
Volume 75, Issue 5, Pages (May 2003)
DOI: /S (02)
Copyright © 2003 The Society of Thoracic Surgeons Terms and Conditions

2. Fig 1
(a) A 29-week fetal heart with a tripartite hypoplastic right ventricle, comprising inlet (I), apical trabecular (T), and outlet (O) components. The outlet tapered to muscular atresia. (b) The youngest case, at 18 weeks gestation, had a well-developed pulmonary trunk (PT) leading to a nonpatent pulmonary valve. (c) This heart from a fetus of 22 weeks gestation had muscular atresia of the outflow tract and a cord-like atretic pulmonary trunk (PT). (d) The cavity of the right ventricle in this heart of 20 weeks gestation was severely reduced by muscular hypertrophy. A narrow infundibulum led to the imperforate pulmonary valve (arrow).
The Annals of Thoracic Surgery  , DOI: ( /S (02) )
Copyright © 2003 The Society of Thoracic Surgeons Terms and Conditions

3. Fig 2
Photomicrographs showing the atrioventricular conduction system in the heart of 20 weeks gestation. (a) The atrioventricular node (AVN) was sited in its regular location, and continued into the penetrating bundle of His (AVB) passing towards the ventricular septum (Masson’s trichrome stain, ×40). (b) The atrioventricular bundle (BB), enclosed by fibrous tissue, was located on the crest of the muscular ventricular septum (Masson’s trichrome stain, ×16). (LV = left ventricle; RV = right ventricle.) (c) The branching bundle separates into the proximal portions of the left (LBB) and right bundle branches (RBB) (Masson’s trichrome stain, ×16).
The Annals of Thoracic Surgery  , DOI: ( /S (02) )
Copyright © 2003 The Society of Thoracic Surgeons Terms and Conditions