title: The effect of pacing-induced heart rate variation on longitudinal and circumferential regional myocardial function after acute beta-blockade--a cardiac ultrasound study.
abstract: OBJECTIVE
  To evaluate the effect of acute beta-blockade in combination with differing heart rates on longitudinal and circumferential regional myocardial function using Doppler myocardial imaging and two-dimensional-echocardiography.
  
  
  RESULTS
  In seven pigs the following echocardiographic indices were measured at baseline, after beta-blockade both without and with atrial pacing: wall thickening fraction, fractional shortening, myocardial peak systolic velocity, transmyocardial velocity gradient and systolic velocity time integral of the posterolateral wall in short-axis view; mitral valve plane excursion, myocardial peak systolic velocity and systolic velocity time integral of the posterolateral wall in an apical five-chamber view. Peak systolic velocities and velocity gradients decreased significantly following acute beta-blockade but no further decay occurred at high heart rate due to pacing. The velocity time integrals and mitral valve plane excursion showed a tendency to decrease following beta-blockade but only after pacing were they significantly reduced. The wall thickening fraction and fractional shortening showed a significant reduction after beta-blockade but no further decay after pacing.
  
  
  CONCLUSIONS
  Changes in systolic velocities and velocity gradients were independent of heart rate reduction under high dosage beta-blockade, whereas wall thickening fraction, mitral valve plane excursion and velocity time integrals changed due to pacing.
authors.affiliation: Linköping Heart Center, University Hospital, Linköping, Sweden.
authors.forename: J M
authors.initials: JM
authors.lastname: Strotmann
authors.forename: B
authors.initials: B
authors.lastname: Janerot-Sjöberg
authors.forename: P
authors.initials: P
authors.lastname: Kimme
authors.forename: B
authors.initials: B
authors.lastname: Fröhlich
authors.forename: J U
authors.initials: JU
authors.lastname: Voigt
authors.forename: A B
authors.initials: AB
authors.lastname: Schreckenberger
authors.forename: L
authors.initials: L
authors.lastname: Hatle
authors.forename: G R
authors.initials: GR
authors.lastname: Sutherland
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D001783:Blood Flow Velocity; D004452:Echocardiography / Q000379:methods*; D006321:Heart / Q000033:anatomy & histology / Q000187:drug effects; D006439:Hemodynamics; D023421:Models, Animal; D009200:Myocardial Contraction / Q000187:drug effects*; D013552:Swine; D016277:Ventricular Function, Left / Q000187:drug effects* / Q000502:physiology*
chemical_list: D000319:Adrenergic beta-Antagonists