Maximal ascending and descending slopes of the T wave in men and women.
To investigate possible sex differences in the dynamics of T wave generation, the maximum instantaneous slope of the ascending and descending limbs of the T wave (max dV/dt and min dV/dt, respectively), were calculated. These rate of repolarization parameters, as well as more traditional repolarization duration parameters (QT, JT, Q to T wave peak [QTm] and J to T wave peak [JTm]), were measured by computer using digitized electrocardiograms (ECGs) from the V5 lead in 562 normal subjects (443 men and 119 women; mean age 37 years), whose heart rates (HRs) were confined to one of three narrow ranges, namely 60 +/- 1, 70 +/- 1, or 80 +/- 1 beats/min. In both men and women, for each HR range absolute values of min dV/dt exceeded those of max dV/dt (P < .0001). However, absolute values of both max dV/dt and min dV/dt were consistently greater in men than in women for each HR range (P < .0001 at HR 60 +/- 1; P < .02 at HR 70 +/- 1, or 80 +/- 1). By using correlation analysis, max dV/dt and min dV/dt were shown to be independent of the repolarization duration variables (r < .30). Thus, whereas in both men and women the descending limb of the T wave is steeper than the ascending limb, the maximum slope of each limb of the T wave is steeper in men than in women. These findings add to a growing body of data indicating fundamental sex differences in the physiology of cardiac repolarization and propensity to torsade de pointes.
Yang
H
H
Arrhythmia Center, Sinai Hospital Detroit, Michigan 48235, USA.
Elko
P
P
Fromm
B S
BS
Baga
J J
JJ
Pires
L A
LA
Schuger
C D
CD
Steinman
R T
RT
Lehmann
M H
MH
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012727:Sex Characteristics; D012815:Signal Processing, Computer-Assisted