Cheng Y, Schwartz J, Vokonas P S, Weiss S T, Aro A, Hu H
Department of Epidemiology, Harvard School of Public Health, Department of Veterans Affairs Outpatient Clinic, Boston, Massachusetts, USA.
Am J Cardiol. 1998 Sep 1;82(5):594-9. doi: 10.1016/s0002-9149(98)00402-0.
Recent research indicates that cumulative exposure to lead may be more toxic than previously thought. This study was undertaken to examine the relation of low-level lead exposure to electrocardiographic (ECG) conduction disturbances among 775 men who participated in the Normative Aging Study (average age 68 years; range 48 to 93). We used K-x-ray fluorescence to measure lead levels in the tibia and patella, and graphite furnace atomic absorption spectroscopy to measure blood lead levels. The mean (SD) values for blood lead, tibia lead, and patella lead were 5.8 (3.4) microg/dl, 22.2 (13.4) microg/g, and 30.8 (19.2) microg/g, respectively. Bone lead levels were found to be positively associated with heart rate-corrected QT and QRS intervals, especially in younger men. Specifically, in men <65 years of age, a 10 microg/g increase in tibia lead was associated with an increase in the QT interval of 5.03 ms (95% confidence interval [CI], 0.83 to 9.22) and with an increase in the QRS interval of 4.83 ms (95% CI, 1.83 to 7.83) in multivariate regression models. In addition, an elevated bone lead level was found to be positively associated with an increased risk of intraventricular block in men <65 years of age and with an increased risk of atrioventricular (AV) block in men > or = 65 years of age. After adjustment for age and for serum high-density lipoprotein (HDL) level, a 10 microg/g increase in tibia lead was associated with an odds ratio (OR) of 2.23 (95% CI, 1.28 to 3.90) for intraventricular block in men <65 years of age and with an OR of 1.22 (95% CI, 1.02 to 1.47) for AV block in men > or = 65 years of age. Blood lead level was not associated with any of the ECG outcomes examined. The results suggest that cumulative exposure to lead, even at low levels, may depress cardiac conduction.
近期研究表明，铅的累积暴露可能比之前认为的毒性更大。本研究旨在调查775名参与标准衰老研究的男性（平均年龄68岁；范围48至93岁）中低水平铅暴露与心电图（ECG）传导障碍之间的关系。我们使用K-X射线荧光法测量胫骨和髌骨中的铅含量，并用石墨炉原子吸收光谱法测量血铅水平。血铅、胫骨铅和髌骨铅的均值（标准差）分别为5.8（3.4）微克/分升、22.2（13.4）微克/克和30.8（19.2）微克/克。发现骨铅水平与心率校正的QT和QRS间期呈正相关，尤其是在较年轻男性中。具体而言，在年龄<65岁的男性中，胫骨铅含量每增加10微克/克，在多变量回归模型中，QT间期增加5.03毫秒（95%置信区间[CI]，0.83至9.22），QRS间期增加4.83毫秒（95%CI，1.83至7.83）。此外，发现骨铅水平升高与年龄<65岁男性的室内传导阻滞风险增加以及年龄≥65岁男性的房室（AV）传导阻滞风险增加呈正相关。在调整年龄和血清高密度脂蛋白（HDL）水平后，年龄<65岁男性的胫骨铅含量每增加10微克/克，室内传导阻滞的比值比（OR）为2.23（95%CI，1.28至3.90），年龄≥65岁男性的AV传导阻滞的OR为1.22（95%CI，1.02至1.47）。血铅水平与所检查的任何ECG结果均无关联。结果表明，即使是低水平的铅累积暴露也可能抑制心脏传导。
