Related Experiment Video
Updated: May 5, 2026
Isolation and Functional Characterization of Human Ventricular Cardiomyocytes from Fresh Surgical Samples
Published on: April 21, 2014
Sexual dimorphism in the electrocardiographic dynamics of human ventricular repolarization: characterization in true
1Department of Internal Medicine, Division of Cardiology, University of Michigan and Veterans Administration Medical Center, Ann Arbor, Michigan, USA.
Background:
Previous characterizations of sex differences in ST-T waveform voltages have largely focused on amplitudes at selected time points during repolarization, subject to potential distortions from variations in heart rate (HR) or reliance on a JT-normalized time scale.
Methods And Results:
Using digitized 12-lead ECGs from 553 normal adults (426 males) with HRs confined to 60+/-1, 70+/-1, or 80+/-1 bpm, we derived X, Y, and Z lead voltages and then generated, for each HR category by sex, summary (population mean) resultant spatial vector amplitudes (ST-T(XYZ)) and instantaneous slopes (dV/dt(XYZ)) at successive 4-ms intervals following the J point. Within each HR category, there was an early intersex divergence of ST-T(XYZ) trajectories (95% CIs nonoverlapping), with men exhibiting 2- to 3-fold greater dV/dt(XYZ) values during the ST segment and achieving greater maximum T(XYZ) and dV/dt(XYZ) values than women; descending T(XYZ) limbs were relatively more concordant between sexes but still steeper in men. The early sex differences in repolarization dynamics persisted in multiple regression analyses that took into account age and a morphometric index of left ventricular mass. In men, absolute values of extrema of T(XYZ) and dV/dt(XYZ) varied inversely with HR.
Conclusions:
At physiological resting HRs, the spatial ST-T vector voltage time trajectory is steeper in men than in women, beginning virtually from the J point. In addition to its mechanistic implications, the demonstration of marked sensitivity of ST-T(XYZ) and especially dV/dt(XYZ) to sex raises the possibility that these time-based, ECG-derived parameters might be informative in pathophysiological studies of ventricular repolarization.
Related Concept Videos
01:19Electrophysiology of Normal Cardiac Rhythm
01:29Electrocardiogram
Three major waveforms are present in a typical ECG recording: the P wave, the QRS complex, and...
01:25Correlation between ECG and Cardiac Cycle
A cardiac action potential originates in the SA node and spreads throughout the atria and the AV node in approximately 0.03 seconds. This results in the P wave in an ECG and triggers atrial contraction. The action potential is then briefly slowed at the AV node, allowing the atria to contract and fill the ventricles with blood before...
01:30Cardiac Action Potential
The cardiac action potential process involves a series of phases characterized by the movement of ions across the cardiac cell membranes, leading to the depolarization and repolarization of the cardiac myocytes.
Ionic Basis of Cardiac Action Potentials
01:28Electrocardiogram Fundamentals
An electrocardiogram (ECG) is a diagnostic tool for identifying cardiac conditions such as arrhythmias, conduction abnormalities, and myocardial ischemia.
Definition
An electrocardiogram (ECG) visualizes the heart's electrical activity by tracing the electrical movement associated with each heartbeat on a graph or monitor. As the heart beats, an electrical wave passes through it, correlating with the cardiac cycle events.
Parts of an ECG
An ECG utilizes electrodes on the skin...
01:30Dysrhythmias V: Evaluating Dysrhythmias