Anatomy of the left atrium for interventional electrophysiologists

Pacing Clin Electrophysiol. 2010 May;33(5):620-7. doi: 10.1111/j.1540-8159.2009.02659.x. Epub 2009 Dec 18.


Increasingly, interventional procedures require accessing the left atrium from the inside of the heart as well as from the pericardial space. The right phrenic nerve running along the fibrous pericardium is close to the atrial insertion of the right superior pulmonary vein while the left phrenic nerve passes over the left atrial appendage. Posteriorly, the esophagus descends adjacent to the fibrous pericardium covering the posterior and postero-inferior walls of the left atrium. The component parts of the left atrium are reviewed with emphasis on the structure of the atrial septum, the left atrial ridge, the mitral isthmus, and the left atrial walls. Although the atrial walls are mainly smooth, pits and crevices are common in the region of the mitral isthmus and the vicinity of the os of the atrial appendage. The muscular rim around the valve of the oval fossa delimits the extent of the true atrial septum. Interatrial muscular connections exist at the septum, along Bachmann's bundle and also at the muscular sleeves of the coronary sinus and pulmonary veins. Anatomical features relevant to interventional electrophysiologists are highlighted.

Publication types

  • Review

MeSH terms

  • Atrial Function*
  • Atrial Septum / anatomy & histology
  • Electrophysiological Phenomena*
  • Heart Atria / anatomy & histology*
  • Heart Atria / innervation*
  • Humans
  • Pericardium / anatomy & histology
  • Pericardium / innervation
  • Phrenic Nerve / anatomy & histology
  • Phrenic Nerve / physiology
  • Pulmonary Veins / anatomy & histology