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SEX DIFFERENCES IN THE QT INTERVAL

Sex differences in ventricular repolarization patterns between women and men have been studied extensively. They are important as they have direct implications for susceptibility to ventricular arrhythmias. It has been shown that a longer QT interval and a lower T-wave amplitude, which reflect a longer duration of repolarization, are present on the surface ECGs of women as compared to men (Figure 16.1). 

QT間期的性別差異

女性和男性之間心室復(fù)極模式的性別差異已被廣泛研究。研究這些差異有重要意義，因?yàn)樗鼈儗?duì)室性心律失常的易感性有直接影響。 研究顯示與男性相比，女性的體表ECG上QT間期更長(zhǎng)、T波振幅更低，這反映了女性的心室復(fù)極時(shí)間更長(zhǎng)（圖16.1）。

圖 16.1. 女性和男性的V3導(dǎo)聯(lián)形態(tài)。兩條水平線分別表示Q-Q線和J點(diǎn)水平與Q-Q平行的水平線。箭頭所示為J點(diǎn); 短豎線標(biāo)記J點(diǎn)后60 ms的點(diǎn); 斜線將J點(diǎn)與上述點(diǎn)連接。A.女性形態(tài)：J點(diǎn)處于Q-Q線的水平，ST角度為19度。B.男性形態(tài)：J點(diǎn)在Q-Q線上方> 0.1 mV，ST角為36度。經(jīng)過(guò)允許修改。

Bidoggia et al measured repolarization in 27 castrated men, 26 women with virilization syndromes,and 53 control subjects pair-matched for age and sex. The study reported delayed repolarization in castrated men compared to normal men and shorter and faster repolarization in women with virilization compared to normal women and castrated men.Sex differences in QT duration become apparent from the time of puberty and subside after the age of 50 (Table 16.2, Figure 16.2).The QT interval shortens during puberty in boys, and this difference persists through early adulthood. This age-related change, along with Bidoggia’s findings, suggests that testosterone may contribute to sex differences in QT duration. At the receptor level, androgen receptors have been identified in the ventricles, and androgen receptor mRNA has been identified in infant male and female human right ventricles, suggesting its involvement in repolarization.

Bidoggia等測(cè)量了27名去勢(shì)男性、26名患男性化綜合征的女性和53名年齡和性別匹配的對(duì)照受試者的復(fù)極情況。該研究發(fā)現(xiàn)與正常男性相比，去勢(shì)男性的復(fù)極化延遲。與去勢(shì)男性相比，男性化的女性復(fù)極更短、更快。QT間期的性別差異從青春期開(kāi)始變明顯，50歲以后開(kāi)始消退（表16.2，圖16.2）。男孩從青春期開(kāi)始QT間期縮短，這種差別在成年早期持續(xù)存在。這種與年齡有關(guān)的變化與Bidoggia的發(fā)現(xiàn)共同表明睪酮可能是導(dǎo)致QT間期性別差異的原因。在受體水平上，心室中已經(jīng)被證實(shí)存在雄激素受體，在男女性嬰幼兒的右心室中也已經(jīng)被證實(shí)存在雄激素受體mRNA，表明其參與復(fù)極。

圖 16.2. 9歲年齡組女性和男性的平均 QTc。經(jīng)過(guò)允許后修改。

（翻譯：王彥江；校對(duì)：姜運(yùn)秋）

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