title: The comparative relationships between locations of the papillary muscles and electrophysiologic QRS axis in patients with atrioventricular septal defect and common as opposed to separate orifices in the valve guarding the common atrioventricular junction.
abstract: BACKGROUND
  Knowledge regarding factors that influence deviation of the QRS axis is important when seeking to differentiate between physiological and pathological changes. We hypothesised that, in contrast to those patients with an atrioventricular septal defect and common atrioventricular junction permitting only atrial shunting, those associated with ventricular shunting would show no relationship between the positions of the papillary muscles and the degree of the leftward deviation of the QRS axis.
  
  
  METHODS
  We compared the positions of endocardial origin of the papillary muscles, and the frontal plane QRS axis, in patients with atrioventricular septal defects and common atrioventricular junction permitting exclusively atrial as opposed to atrial and ventricular shunting.
  
  
  RESULTS
  We analysed 18 patients with atrial and ventricular shunting and 23 patients with exclusively atrial shunting. The correlation coefficient between the ratio of distances of the papillary muscles from the mid-septum and the amount of leftward deviation in the frontal plane QRS axis was 0.1 (p=0.4) in those with ventricular shunting and 0.26 (p=0.01) in those with exclusively atrial shunting.
  
  
  CONCLUSIONS
  In contrast to patients with the so-called primum form of atrioventricular septal defect, in whom the locations of the papillary muscles correlate with the degree of QRS axis, such relationships are lacking in patients with defects permitting both atrial and ventricular shunting. It may be, therefore, that the presence of ventricular shunting and/or their younger age causes pressure overload, which negates the leftward QRS forces caused by the abnormally positioned papillary muscles.
authors.affiliation: 1Academic Unit of Ophthalmology,Institute of Inflammation and Ageing, University of Birmingham,Birmingham,United Kingdom.
authors.forename: Liying
authors.initials: L
authors.lastname: Low
authors.affiliation: 2Duke University Medical Center,Divisions of Cardiology and Pediatric Cardiology,Durham North Carolina,United States of America.
authors.forename: Salim F
authors.initials: SF
authors.lastname: Idriss
authors.affiliation: 3Institute of Genetic Medicine,Newcastle University,Newcastle-upon-Tyne,United Kingdom.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Anderson
authors.affiliation: 4Department of Health Services University of Washington Seattle,Washington,United States of America.
authors.forename: Charles
authors.initials: C
authors.lastname: Maynard
authors.affiliation: 2Duke University Medical Center,Divisions of Cardiology and Pediatric Cardiology,Durham North Carolina,United States of America.
authors.forename: Galen
authors.initials: G
authors.lastname: Wagner
authors.affiliation: 5Children's Heart Centre,Children's University Hospital,Lund,Sweden.
authors.forename: Nina
authors.initials: N
authors.lastname: Hakacova
mesh_terms: D002675:Child, Preschool; D004452:Echocardiography; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006325:Heart Atria / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006329:Heart Conduction System / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006343:Heart Septal Defects / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007223:Infant; D008297:Male; D010210:Papillary Muscles / Q000000981:diagnostic imaging*; D012189:Retrospective Studies
keywords: QRS axis; atrioventricular septal defect; papillary muscles