Abstract:
BACKGROUND:The suggestion that increased QT dispersion (QTD) is due to increased differences in local action potential durations within the myocardium is wanting. An alternative explanation was sought by relating QTD to vectorcardiographic T-loop morphology. METHODS AND RESULTS:The T loop is characterized by its amplitude and width (defined as the spatial angle between the mean vectors of the first and second halves of the loop). We reasoned that small, wide ("pathological") T loops produce larger QTD than large, narrow ("normal") loops. To quantify the relationship between QTD and T-loop morphology, we used a program for automated analysis of ECGs and a database of 1220 standard simultaneous 12-lead ECGs. For each ECG, QT durations, QTD, and T-loop parameters were computed. T-loop amplitude and width were dichotomized, with 250 microV (small versus large amplitudes) and 30 degrees (narrow versus wide loops) taken as thresholds. Over all 1220 ECGs, QTDs were smallest for large, narrow T loops (54.2+/-27.1 ms) and largest for small, wide loops (69. 5+/-33.5 ms; P<0.001). CONCLUSIONS:QTD is an attribute of T-loop morphology, as expressed by T-loop amplitude and width.
journal_name
Circulationjournal_title
Circulationauthors
Kors JA,van Herpen G,van Bemmel JHdoi
10.1161/01.cir.99.11.1458subject
Has Abstractpub_date
1999-03-23 00:00:00pages
1458-63issue
11eissn
0009-7322issn
1524-4539journal_volume
99pub_type
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