高盐摄入及补钾对健康成人QT间期离散度的影响

Effects of high salt intake and potassium supplement on QT interval dispersion in normotensive healthyadults

目的探讨慢性盐负荷及补钾对健康成人QT间期离散度（QTd）、T波峰-末间期（Tp-Te）的影响。方法选取64例28-60岁血压正常者参与为期3周的慢性盐负荷及补钾试验，包括基线调查3d（基线期），低盐饮食（低盐期）、高盐饮食（盐负荷期）和高盐补钾饮食（高盐补钾期）各7d。各期均测量体质量、血压，记录心电图，测量QT间期、QTd、校正QTd（QTdc）及Tp-Te。结果低盐期QTd、QTde、TO-Te均〈基线期（QTd，45．6±15．6对52．1＋23．4，P〈0．05；QTdc，55．6-＋19．4对61．6_＋23．6，P〈0．05；To-Te，79．8±8．5对85．0±10．6，P〈O．01）；盐负荷后QTdc、Tp-Te〉低盐期（QTdc，60．3＋19．4对55．6±19．4，P〈0．05；To．Te，83．0±10．1对79．8＋8．5，P〈0．01）；在高盐摄入的基础上大剂量口服补钾QTd、QT-dc、Tp-Te均较高盐期缩小（QTd，42．6±15．1对47．4±19．0，P〈0．05；QTde，52．2±18．0对60．3±19．4，P〈0．05；To-Te，79．1±8．5对83．0±10．1，P〈0．01）。结论盐负荷可升高血压并使QTd、QTde及rrp·R增加，补钾可以减低高盐对QTd、QTde、T0-Te的影响，提示补钾可通过缩短心肌复极时间，降低心脏复极不均一性，对心律失常可能有一定预防作用。

To investigate the effects of dietary sodium intake on QT interval dispersion （QTd） in normotensive healthy adults and the protective effect of dietary potassium. Methods Sixtyfour normotensive subjects, aged 28 to 60, were enrolled and sequentially maintained on a protocol with 3 days baseline investigation, 7 days low salt diet （ 3 g/d, NaC1）, 7 days high salt diet （ 18 g/d）, and high salt diet with potassium supplementation （4. 5 g/d, KC1） for another 7 days. On the second day and the last three days of each period, blood pressure were measured by physicians who were trained and standardized and electrocardiogram was recorded in the end of each period. QT interval,QTd and TpeakTend interval （TpTe） were measured and calculated. Results After salt loading, corrected QT interval （ QTc）, corrected QT interval dispersion （QTdc） and TpTe were prolonged （ QTdc ,60. 3＋19.4 vs 55.6＋19. 4 ,P〈0.05 ;TpTe,83.0_＋10. 1 vs. 79. 8＋8. 5 ,P〈 O. O1 ）. Surprisingly, all the changes were reversed by potassium supplementation （QTd,42. 6＋15.1 vs 47.4＋ 19. 0,P〈0.05 ;QTdc ,52.2±18.0 vs 60. 3±19.4,P〈0. 05 ;TpTe,79. 1 ±8. 5 vs 83.0±10. 1 ,P〈O. 01 ）. Condusions Salt loading induced high blood pressure and prolonged QT interval, QTd and TpTe in healthy adults, while dietary potassium supplementation could reverse these alterations. It suggests that potassium supplementation may not only lower the blood pressure, but also improves heterogeneities of repatriation time and maybe prevent arrhvthmias.