title: The normal sequence of right and left atrial contraction.
abstract: OBJECTIVE
  To study the sequence of atrial activation and the interatrial electromechanical delay (IEmD) noninvasively in healthy subjects during sinus rhythm (SR).
  
  
  RESULTS
  In 66 SR healthy subjects P-wave activation was analyzed by means of vectorcardiography. The timing of atrial contractions was measured as the intervals between the P-wave and the A-wave of the Doppler right and left ventricular inflows (P-A(t) and P-A(m)), and IEmD was calculated as the algebraic difference P-A(m)- P-A(t). In the horizontal plane the vectorcardiographic P-loop was anteroposterior ("typical", 41 subjects), anterior (18), or posterior (7). IEmD (mean +/- SE 17 +/- 8 ms) was directly related to R-R and P-R intervals. IEmD was significantly shorter in anterior and posterior P loops than in the typical (6.5 +/- 5.3 and 8.1 +/- 10.1, respectively, vs 24.2 +/- 3.1 ms). In the posterior P-loop group, who exhibited longer P-A(t), mitral E-wave velocity and E/A ratio were reduced, and left atrial booster function was increased.
  
  
  CONCLUSIONS
  IEmD was widely variable in SR, reflecting the origin site of sinus impulse, which independently influenced ventricular filling dynamics.
authors.affiliation: Department of Cardiology, Careggi Hospital, University of Florence, Italy. g.barletta@dfc.unifi.it
authors.forename: G
authors.initials: G
authors.lastname: Barletta
authors.forename: R
authors.initials: R
authors.lastname: Del Bene
authors.forename: F
authors.initials: F
authors.lastname: Fantini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016275:Atrial Function; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009200:Myocardial Contraction / Q000502:physiology*; D012016:Reference Values; D014672:Vectorcardiography / Q000379:methods