title: Dynamics of left ventricular apex rotation during angioplasty: a sensitive index of ischemic dysfunction.
abstract: BACKGROUND
  Apex rotation has been shown to provide a reliable index of the dynamics of left ventricular (LV) twist. In this study, we aimed to characterize twist at baseline and during acute ischemia in 20 patients undergoing percutaneous transluminal coronary angioplasty to the left anterior descending (LAD) artery and to test whether an old myocardial infarction or collateral flow affected twist dynamics.
  
  
  RESULTS
  Among patients with no previous infarction, five had no collaterals (group A) and six had angiographically visible collaterals (group B). Previous anterior infarction was present in nine patients (group C). Data were acquired with the LAD angioplasty wire passed beyond the apex using a view aligned with the LV long axis. Frame-by-frame dynamics of apex rotation were measured from the angular movement of the portion of the wire that traversed the apex. Aortic pressure recordings allowed precise temporal definition of the cardiac cycle. Dynamics of apex rotation were measured at fixed intervals until 60 seconds of occlusion and up to 60 seconds of reperfusion. In group A, counterclockwise apex rotation (twist) during ejection of -22.0+/-1.7 degrees (mean+/-SEE) was followed by rapid clockwise rotation (untwist) during isovolumic relaxation. During 60 seconds of ischemia, maximum apex rotation decreased to -8.2+/-2.0 degrees (P<.001 versus baseline). In group B, baseline apex rotation was similar (-26.2+/-6.9 degrees) to that in group A, but ischemia had less effect, with apex rotation values of -17.7+/-3.4 degrees (P<.05 versus group A values). Group C was characterized by reduced baseline apex rotation values (-9.7+/-3.1 degrees, P<.05 versus group A values), with little change observed during ischemia (-8.1+/-2.6 degrees).
  
  
  CONCLUSIONS
  Apex rotation, an index of ventricular twist, is sensitive to acute ischemia in patients without previous myocardial infarction. Visible collaterals to the ischemic region attenuate the acute ischemic response at 60 seconds. Previous myocardial infarction causes abnormalities in the baseline twist pattern with no further deterioration at 60 seconds of ischemia.
authors.affiliation: Department of Medicine, The University of Calgary, The Foothills Hospital, Alberta, Canada.
authors.forename: M L
authors.initials: ML
authors.lastname: Knudtson
authors.forename: P D
authors.initials: PD
authors.lastname: Galbraith
authors.forename: K L
authors.initials: KL
authors.lastname: Hildebrand
authors.forename: J V
authors.initials: JV
authors.lastname: Tyberg
authors.forename: R
authors.initials: R
authors.lastname: Beyar
mesh_terms: D000328:Adult; D015906:Angioplasty, Balloon, Coronary; D003097:Collateral Circulation; D006801:Humans; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications; D017202:Myocardial Ischemia / Q000150:complications / Q000503:physiopathology*; D012399:Rotation; D012680:Sensitivity and Specificity; D013599:Systole; D016277:Ventricular Function, Left