title: The Thebesian valve and its significance for electrophysiologists.
abstract: BACKGROUND
  Invasive cardiac procedures, such as arrhythmia ablation, cardiac resynchronisation therapy, percutaneous mitral annuloplasty and retrograde cardioplegia delivery require cannulation of the coronary sinus (CS). Detailed knowledge of the CS ostium region, including recognition of the presence of the Thebesian valve which sometimes covers the sinus, is a key to successfully carryout such procedures.
  
  
  METHODS
  In the present study, 160 autopsied human hearts from both sexes were examined for the presence of the Thebesian valve. If identified, the histological structure of the valve was studied.
  
  
  RESULTS
  Five types of the CS valve were distinguished; all of them presented with a typical histological structure with the exception of the cord-like type, in which cells were similar to those of the conduction system of the heart.
  
  
  CONCLUSIONS
  Proper identification of the CS valve and analysis of its size and histological features could have important implications for electrophysiologists.
authors.affiliation: Department of Anatomy, Jagiellonian University Medical College, Krakow, Poland. malg.mazur@uj.edu.pl.
authors.forename: M
authors.initials: M
authors.lastname: Mazur
authors.forename: R
authors.initials: R
authors.lastname: Tomaszewska
authors.forename: A
authors.initials: A
authors.lastname: Pasternak
authors.forename: M
authors.initials: M
authors.lastname: Kuniewicz
authors.forename: J A
authors.initials: JA
authors.lastname: Walocha