Shonosuke Ryu

Intramural Purkinje Cell Network of Sheep Ventricles as the Terminal Pathway of Conduction System

To identify the anatomical basis for cardiac electrical signal conduction, particularly seeking the intramural terminals of conduction pathway within the ventricles, sheep hearts were examined compared with human hearts utilizing the characteristic morphology of Purkinje cells as a histological marker. In 15 sheep and five human autopsies of noncardiac death, prevalence of Purkinje or Purkinje‐type cells were histologically examined in the atrioventricular node, its distal conduction pathway, the interventricular septum, and the right‐ and left‐ventricular free walls. Myocardial tissue cleavages were examined in the transmural sections (along cardiac base‐to‐apex axis) obtained from the septum and ventricular free walls. Serial histological sections through virtually the entirety of the septum in selected sheep were used as the basis of a three‐dimensional reconstruction of the conduction pathway, particularly of the intramural Purkinje cell network. Purkinje cells were found within the mural myocardium of sheep ventricles whereas no intramural Purkinje‐type cell was detected within the human ventricles. In the sheep septum, every intramural Purkinje cell composed a three‐dimensional network throughout the mural myocardium, which proximally connected to the subendocardial extension of the bundle branches and distally formed an occasional junction with ordinary working myocytes. The Purkinje‐cell network may participate in the ventricular excitation as the terminal conduction pathway. Individual connections among the Purkinje cells contain the links of through‐wall orientation which would benefit the signal conduction crossing the architectural barriers by cleavages in sheep hearts. The myocardial architectural changes found in diseased hearts could disrupt the network links including those with transmural orientation. Anat Rec, 2009.

Acute myocardial infarction in a young adult patient with simultaneous total occlusion of double coronary arteries

We report an otherwise healthy 16-year-old male patient with simultaneous double vessel acute myocardial infarction. Coronary angiography (CAG) showed simultaneous total occlusion of the left anterior descending artery (LAD) and the left circumflex artery (LCX). Emergent percutaneous coronary intervention (PCI) was performed on the diseased lesions. After PCI, coronary artery aneurysms were found in both the LAD and LCX. The patient was discharged after a 56-day hospitalization. The New York Heart Association (NYHA) Functional Classification at discharge was II. Medical therapy became ineffective over time because of exacerbated ischemic mitral regurgitation; successful mitral annuloplasty was performed. The post-operative course was uneventful.