Prolongation of the QTc Interval Is Seen Uniformly During Early Transmural Ischemia
David N. Kenigsberg, MD2,
Sanjaya Khanal, MD2,
Marcin Kowalski, MD and
Subramaniam C. Krishnan, MD1,*
Henry Ford Heart and Vascular Institute, Henry Ford Hospital, Detroit, Michigan.
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Figure 1 Electrocardiographic Changes Induced by Transmural Ischemia
(A) Single electrocardiographic complex from lead V2 obtained under baseline conditions, before the start of the angioplasty of the left anterior descending coronary artery (LAD). (B) Single electrocardiographic complex from the same lead shown in A is displayed 25 s after balloon inflation in the proximal LAD. The QT interval is seen to prolong by 44 ms. (C) The 2 complexes seen in A and B are superimposed to better illustrate ischemia-induced changes showing prolongation of QT interval.
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Figure 2 QTc Interval Prolongation Induced by Brief Episodes of Transmural Ischemia in 74 Patients Analyzed by the MUSE Automated System
(A) Line graph demonstrating transmural ischemia-induced QTc interval prolongation in all 74 patients. (B) Bar graph displaying average QTc interval in 74 patients at baseline, during balloon inflation, and after deflation. The QTc interval is prolonged by 32 ms with balloon inflation and partially returns to baseline upon deflation.
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Figure 4 Time Course of Ischemia-Induced Changes in Different Components of the ECG
Analysis performed with the MUSE automated system. Prolongation of the QTc interval occurs earlier than the established criteria for acute ischemia (ST-segment elevation [STE], ST-segment depression [STD]  1 mm in 2 contiguous leads). ECG = electrocardiogram; TWC = T-wave change.
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