title: Anatomy of the left main coronary artery of particular relevance to ablation of left atrial and outflow tract arrhythmias.
abstract: BACKGROUND
  Left main coronary artery (LMCA) damage is a rare but catastrophic complication of cardiac ablation procedures.
  
  
  OBJECTIVE
  The purpose of this study was to describe the anatomic relationships of the LMCA to its adjacent structures using analysis of computed tomographic coronary angiograms (CTCA).
  
  
  METHODS
  We studied 100 patients (55 males, age 51 ± 10 years) who were investigated for chest pain with CTCA. The relationships between the LMCA and adjacent structures were described by analysis of 2-dimensional images and 3-dimensional reconstructions.
  
  
  RESULTS
  The LMCA coursed within 5 mm of the anterior left atrial endocardium and/or base of left atrial appendage in 49% (within 2 mm in 17%) and from the pulmonary artery in 90% (within 2 mm in 43%). The LMCA was within 5 mm of the right ventricular outflow tract in 1%. In 4% the LMCA coursed inferiorly, remaining within 5 mm of the left aortic sinus of Valsalva at a vertical distance >5 mm from the inferior margin of the LMCA ostium.
  
  
  CONCLUSIONS
  The LMCA is often intimately related to the anterior left atrium, left atrial appendage base, and pulmonary artery and occasionally to the inferior part of the left aortic sinus of Valsalva and thus is exposed to the risk of injury during ablation in these areas. The LMCA is rarely close to the right ventricular outflow tract.
authors.affiliation: Department of Cardiology, Cork University Hospital, Cork, Ireland.
authors.forename: Katie A
authors.initials: KA
authors.lastname: Walsh
authors.affiliation: Department of Cardiology, Cork University Hospital, Cork, Ireland. Electronic address: fahysdsl@eircom.net.
authors.forename: Gerard J
authors.initials: GJ
authors.lastname: Fahy
mesh_terms: D000328:Adult; D017115:Catheter Ablation / Q000009:adverse effects* / Q000379:methods; D015331:Cohort Studies; D017023:Coronary Angiography / Q000379:methods; D003331:Coronary Vessels / Q000033:anatomy & histology* / Q000000981:diagnostic imaging* / Q000293:injuries; D004562:Electrocardiography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D007431:Intraoperative Complications / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012720:Severity of Illness Index; D017180:Tachycardia, Ventricular / Q000175:diagnosis / Q000601:surgery*; D014057:Tomography, X-Ray Computed / Q000379:methods; D014694:Ventricular Outflow Obstruction
keywords: Anatomy; Complications; Left main coronary artery; Radiofrequency ablation