title: Continuous ST-segment monitoring during coronary angioplasty using orthogonal ECG leads.
abstract: In order to characterize ST-segment shifts during transient coronary artery occlusion, 24 patients with single-vessel disease were continuously monitored during percutaneous transluminal coronary angioplasty by use of a computerized orthogonal lead system. Changes of ST-segment (J + 60 ms) in leads X, Y, and Z and of the ST vector magnitude were analyzed by using 20 microV as a threshold for significant ST-segment shift. The sensitivity and magnitude of this shift were compared among the left anterior descending, right coronary, and circumflex artery groups (11, 8, and 5 patients, respectively) during balloon inflation. Significant ST-segment shifts were seen in 22 patients (92%) in ST-VM, Y, and Z leads and all patients in lead X (100%). There was no significant difference in sensitivity of either the ST vector magnitude or the most sensitive lead for occlusion detection among the three groups. There was a significantly greater magnitude of ST shift during left anterior descending artery occlusion than during right coronary artery and circumflex artery occlusions in ST-VM. Analysis of the direction of ST shifts in the X, Y, and Z leads showed a characteristic pattern, which could distinguish among the three coronary groups in 21 patients (88%). The presence of collaterals was significantly associated with ST-segment depression in leads oriented toward ischemia (3 of 6 patients) as compared with ST-segment elevation in the absence of collaterals (all of 15 patients), P > .01. It is concluded that ST-segment shift in the orthogonal leads is a reliable marker for myocardial ischemia. It is equally sensitive to occlusion of each of the three major coronary arteries and can thus identify the occluded coronary. An ST-segment depression instead of an elevation was related to the presence of collaterals, which may reflect a lesser degree of ischemia.
authors.affiliation: Research Centre, Hôpital du Sacré-Coeur de Montréal, Québec, Canada.
authors.forename: B F
authors.initials: BF
authors.lastname: Badir
authors.forename: A R
authors.initials: AR
authors.lastname: LeBlanc
authors.forename: J B
authors.initials: JB
authors.lastname: Nasmith
authors.forename: D
authors.initials: D
authors.lastname: Palisaitis
authors.forename: B
authors.initials: B
authors.lastname: Dubé
authors.forename: R
authors.initials: R
authors.lastname: Nadeau
mesh_terms: D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D015906:Angioplasty, Balloon, Coronary / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D003097:Collateral Circulation; D003327:Coronary Disease / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data; D009203:Myocardial Infarction / Q000503:physiopathology; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D014672:Vectorcardiography / Q000295:instrumentation / Q000379:methods* / Q000706:statistics & numerical data