The duration of the QT interval on the surface electrocardiogram represents the time required for all ventricular depolarization and repolarization processes to occur. Among the many physiologic and pathologic factors that contribute to the QT interval, heart rate plays a major role. Several approaches ...
We evaluated atrioventricular conduction time (PR), heart rate (HR), and QT interval patterns defining the range of normality of these electrocardiographic parameters. The PR interval ranged from 154± 10 ms (mean±SD) for HR¤60 to 102±12 ms for HR 120 (range 85180). The absolute mean ...
In parallel, a new model of QT-interval dynamics behavior related to heart rate changes is presented. Since two kinds of QT response have been pointed out, the main idea is to split the modeling process into two steps: 1) the modeling of the fast adaptation, which is inspired by the ...
or LQTS, is when somebody’s QT interval is longer than normal, which should typically be less than half of a cardiac cycle. In fact, for a heart rate of 60 beats per minute, the QT interval’s generally
Slow QT Interval adaptation to heart rate changes in normal ambulatory subjects. Ann Nonin Electrocardiol 2011; 16: 148-155.Razak E, Buncova M, Shusterman V, Winter B, Shen WK, Ackerman MJ, et al. Slow QT interval adapta- tion to heart rate changes in normal ambulatory subjects. Annals ...
The normal physiologic response of the QT interval to an increasing heart rate is to shorten and can be evaluated using the QT/heart rate (QT/HR) ratio during accelerating heart rate (33). In normal individuals, the QT/HR ratio generally exhibits a linear relationship in response to exercise...
The heart rate–corrected QT (QTc) interval exhibits circadian variation. However, little is known about QTc interval variation with month of year. We sought to determine whether the QTc interval varies with month of year. We retrospectively analyzed a database of 24,370 electrocardiograms (ECGs)...
The QT interval is an electrocardiographic measure representing the sum of ventricular depolarization and repolarization, estimated by QRS duration and JT interval, respectively. QT interval abnormalities are associated with potentially fatal ventricular
Objective To investigate the mechanism underlying the changes ofQTinterval. 目的探讨QT间期发生变化的内在机理. 互联网 QTand QTc of electrocardiogram were also prolonged, but in normal range. 心电图QT、QTc有所延长, 但在正常范围内. 互联网
DISCUSSION The major findings of this study are: (i) the rate-corrected QTc interval was not altered during normal pregnancy, but the QT/HR hysteresis lag was shorter and the QT/HR regression residual was higher compared with those of non-pregnant women; and (ii) pregnancies with abnormal ...