Age, Gender, and Autonomic Tone Effects on Surface Electrocardiographic Indices of Ventricular Repolarization

Taneja, Taresh; Larsen, Jennifer A.; Goldberger, Jeffrey J.; Kadish, Alan H.

doi:10.1111/j.1542-474x.2001.tb00121.x

Cited by 7 publications

(8 citation statements)

References 25 publications

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“…Women do have longer corrected QT intervals than men (4,24). Young men have larger T-wave offset dispersion than young and old women, whereas women have greater T-wave complexity after exercise and with autonomic blockade (33). Susceptibility to drug-induced TdP is clearly greater in women than in men (11,22).…”

Section: Discussionmentioning

confidence: 97%

Sex-based transmural differences in cardiac repolarization and ionic-current properties in canine left ventricles

Xiao¹,

Zhang²,

Han³

et al. 2006

American Journal of Physiology-Heart and Circulatory Physiology

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The female sex is associated with longer electrocardiographic QT intervals and increased proarrhythmic risks of QT-prolonging drugs. This study examined the hypothesis that sex differences in repolarization may be associated with differential transmural ion-current distribution. Whole cell patch-clamp and current-clamp were used to study ionic currents and action potentials (APs) in isolated canine left ventricular cells from epicardium, midmyocardium, and endocardium. No sex differences in AP duration (APD) were found in cells from epicardium versus endocardium. In midmyocardium, APD was significantly longer in female dogs (e.g., at 1 Hz, female vs. male: 288 +/- 21 vs. 237 +/- 8 ms; P < 0.05), resulting in greater transmural APD heterogeneity in females. No sex differences in inward rectifier K+ current (I(K1)) were observed. Transient outward K+ current (I(to)) densities in epicardium and midmyocardium also showed no sex differences. In endocardium, female dogs had significantly smaller I(to) (e.g., at +30 mV, female vs. male: 2.5 +/- 0.2 vs. 3.5 +/- 0.3 pA/pF; P < 0.05). Rapid delayed-rectifier K+ current (I(Kr)) density and activation voltage-dependence showed no sex differences. Female dogs had significantly larger slow delayed-rectifier K+ current (I(Ks)) in epicardium and endocardium (e.g., at +40 mV; tail densities, female vs. male; epicardium: 1.3 +/- 0.1 vs. 0.8 +/- 0.1 pA/pF; P < 0.001; endocardium: 1.2 +/- 0.1 vs. 0.7 +/- 0.1 pA/pF; P < 0.05), but there were no sex differences in midmyocardial I(Ks). Female dogs had larger L-type Ca2+ current (I(Ca,L)) densities in all layers than male dogs (e.g., at -20 mV, female vs. male, epicardium: -4.2 +/- 0.4 vs. -3.2 +/- 0.2 pA/pF; midmyocardium: -4.5 +/- 0.5 vs. -3.3 +/- 0.3 pA/pF; endocarium: -4.5 +/- 0.4 vs. -3.2 +/- 0.3 pA/pF; P < 0.05 for each). We conclude that there are sex-based transmural differences in ionic currents that may underlie sex differences in transmural cardiac repolarization.

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Section: Discussionmentioning

confidence: 97%

Sex-based transmural differences in cardiac repolarization and ionic-current properties in canine left ventricles

Xiao¹,

Zhang²,

Han³

et al. 2006

American Journal of Physiology-Heart and Circulatory Physiology

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“…The preferential plane was computed for each individual and the T loop was characterized by two parameters: Teigenvalue (roundness; unitless) and Tavplan (bulginess; μV). Teigenvalue was computed as the squared quotient between the two largest perpendicular axes (eigenvalues) of the T loop in this plane (d1/d2) 2 (where d1 ≥ d2). The T loop has a high Teigenvalue in a healthy individual, but can never have a more abnormal value than 1, for the special case of a circle.…”

Section: Methodsmentioning

confidence: 99%

“…Heterogeneity of ventricular repolarization (VR) is due to intercellular differences in depolarization instants and action potential (AP) morphology 1 . VR modulation is very complex and heart rate (HR), autonomic nervous system activity, gender, and age are some of the major influencing factors 2 . Increase in VR heterogeneity might set the stage for sustained arrhythmias 3 .…”

mentioning

confidence: 99%

Effect of Heart Rate on Ventricular Repolarization in Healthy Individuals Applying Vectorcardiographic T Vector and T Vector Loop Analysis

Vahedi

Haney²,

Jensen

et al. 2011

Annals of Noninvasive Electrocardiology

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Background: Ventricular repolarization (VR) is strongly influenced by heart rate (HR) and autonomic nervous activity, both of which also are important for arrhythmogenesis. Their relative influence on VR is difficult to separate, but might be crucial for understanding while some but not other individuals are at risk for life-threatening arrhythmias at a certain HR. This study was therefore designed to assess the "pure" effect of HR increase by atrial pacing on the ventricular gradient (VG) and other vectorcardiographically (VCG) derived VR parameters during an otherwise unchanged condition.Methods: In 19 patients with structurally normal hearts, a protocol with stepwise increased atrial pacing was performed after successful arrhythmia ablation. Conduction intervals were measured on averaged three-dimensional (3D) QRST complexes. In addition, various VCG parameters were measured from the QRS and T vectors as well as from the T loop. All measurements were performed after at least 3 minutes of rate adaptation of VR.Results: VR changes at HR from 80 to 120 bpm were assessed. The QRS and QT intervals, VG, QRSarea, Tarea, and Tamplitude were markedly rate dependent. In contrast, the Tp-e/QT ratio was rate independent as well as the T-loop morphology parameters Tavplan and Teigenvalue describing the bulginess and circularity of the loop.Conclusions: In healthy individuals, the response to increased HR within the specified range suggests a decreased heterogeneity of depolarization instants, action potential morphology, and consequently of the global VR.Ann Noninvasive Electrocardiol 2011;16(3):287-294 repolarization; heart rate; vectorcardiography; T-wave vector

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“…Rabbits have been intensively studied because of their similarity in the cardiac repolarization currents with human heart. In most studies adult rabbits exhibited clear gender-related differences in repolarization as is evidenced by significantly longer QT, JT intervals and T wavelength and significantly longer APD 30 , APD 50 and APD 90 in females [12][13][14]. However, there are also different reports in which no gender-related differences in the QT interval were observed [15], or the QT interval in female was even shorter than in males [16].…”

Section: Gender-related Difference In Repolarization and The Underlyimentioning

confidence: 99%

“…In hearts isolated from orchiectomized male rabbits, the replacement of dihydrotestosterone (DHT) (for 10-14 days) attenuated the rate-dependent QT-prolongation relative to placebo-treated controls primarily through an effect on ventricular repolarization, as no significant changes in QRS were observed in response to DHT [17]. In ovariectomized rabbits treated with placebo, estradiol or DHT for 3 weeks, although the ECG parameters of the three groups did not differ, APD 30 of papillary muscles in the DHT group was significantly shorter than that of the others at cycle lengths of >500 ms, and the APD 90 of the estradiol group was significantly longer than that of the DHT group at cycle lengths of >1000 ms [18]. While the longer APD 30 in basal right ventricular endocardial action potential in female than male rabbit heart still persists between orchiectomized and ovariectomized rabbit [19], suggesting that extragonadal factors may also contribute to the differences in ventricular repolarization.…”

Section: Gender-related Difference In Repolarization and The Underlyimentioning

confidence: 99%

Evidences of the gender‐related differences in cardiac repolarization and the underlying mechanisms in different animal species and human

Cheng¹

2006

Fundamemntal Clinical Pharma

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Clinical and experimental studies have shown that gender differences exist in cardiac repolarization in various animal species and human, as is evidenced by significantly longer QT, JT intervals and action potential duration in females than in males due to a reduced repolarization reserve in females. The latter is shown by the relatively greater increase in ventricular repolarization and higher incidence of torsades de pointes (TdP) in preparations from females by drugs blocking repolarizing K(+) currents. These results can be modulated by gonadectomy, suggesting that gonadal steroids are important determinants of gender difference in repolarization. In human subjects, QT and JT intervals are longer in women, whereas QT dispersion and Tp-e interval (the interval from the peak to the end of T wave) are longer in men. At slow heart rates greater prolongation in QT and increase in transmural repolarization heterogeneity (i.e. increase in Tp-e) may predispose to TdP tachycardias in women. In healthy postmenopausal women, hormone replacement therapy with estrogen alone usually produced a prolongation of QT interval, while estrogen plus progesterone had no significant effects on QT interval but reduced QT dispersion. Along with these, there are still conflicting data reported. Further work is needed before the elucidation of the basis of gender differences in ventricular repolarization.

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Age, Gender, and Autonomic Tone Effects on Surface Electrocardiographic Indices of Ventricular Repolarization

Abstract: Age and gender demonstrate a complex interaction on indices of myocardial repolarization with different measures behaving differently. These findings have implications for better understanding age and gender effects on myocardial electrophysiology.

Cited by 7 publications

References 25 publications

Sex-based transmural differences in cardiac repolarization and ionic-current properties in canine left ventricles

Sex-based transmural differences in cardiac repolarization and ionic-current properties in canine left ventricles

Effect of Heart Rate on Ventricular Repolarization in Healthy Individuals Applying Vectorcardiographic T Vector and T Vector Loop Analysis

Evidences of the gender‐related differences in cardiac repolarization and the underlying mechanisms in different animal species and human

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