Electrophysiologic effects of magnesium sulfate infusion in patients with cardiac conduction defects.

We report the electrocardiographic and electrophysiologic effects of magnesium (Mg) sulfate infusion in 25 normomagnesemic patients (16 men and 9 women, aged 22-74 years; mean +/? SD, 60.4 +/? 11.9) with different cardiac conduction impairments. Ten patients had chronic ischemic heart disease, two had idiopathic dilated cardiomyopathy, two had hypertensive heart disease, three had valvular heart disease, five had sclerodegenerative heart disease and three had no clinical evidence of cardiac disease. Five patients had trifascicular block [first degree atrioventricular (A-V) block+right bundle branch block (RBBB)+left anterior hemiblock (LAH)], eight had bifascicular block (6 RBBB+LAH, 2 first degree A-V block+RBBB), four had isolated first degree A-V block and eight had bundle branch block [5 RBBB, 3 left bundle branch block (LBBB)]. Before and during Mg infusion (50 mg/min/60 min) we evaluated the A-V (P-R), intraatrial (P-A), suprahisian (A-H), infrahisian (H-V) conduction times, electrical ventricular systole (Q-T), Q-T index (Q-Tc) intraventricular conduction time (QRS) and heart rate. At the end of infusion the P-R, P-A, A-H, H-V increased from 215.4 +/? 36.6, 33.6 +/? 9.1, 112.8 +/? 37.3, 69.0 +/? 12.8 ms to 217.6 +/? 37.1 (p less than 0.002), 33.8 +/? 9.4 (NS), 114.2 +/? 38.1 (p less than 0.005), 69.6 +/? 13.3 (NS) ms. QRS complex did not change (125 +/? 16.9 ms).(ABSTRACT TRUNCATED AT 250 WORDS)     

Biventicular pacing in patients with severe heart failure

According to initial clinical results biventricular pacing seems to be effective in the treatment of patients suffering from drug refractory severe heart failure combined with intraventricular conduction disturbance. Biventricular cardioverter defibrillators and biventricular pacemakers were implanted in patients suffering from drug refractory severe heart failure in 3 and in 2 cases, respectively (follow up > 6 months). NYHA III-IV functional class, low left ventricular ejection fraction (23.2 +/- 5.4%), wide QRS (> 150 ms) with left bundle branch block and lateral dyssynchrony were present in each case. The left ventricle was enlarged in each patient (end-diastolic/end-systolic diameter: 78.6 +/- 9.2/66.2 +/- 8.1 mm). The indications of cardioverter defibrillator implantations were both sustained ventricular tachycardia and ventricular fibrillation, nonsustained ventricular tachycardia combined with syncope in 2 and in 1 case, respectively. The duration of QRS decreased (190 +/- 36 vs. 134 +/- 17 ms, p = 0.012) and wall movement disorder disappeared. At the last follow up every patients were in NYHA II functional class and a decrease in left ventricular diameter could be observed (end-diastolic: 72 +/- 10.4 mm, p = 0.07; end-systolic: 62 +/- 10 mm, p = 0.09). During the follow up period (7.3 +/- 1.7 months) 18 episodes of ventricular arrhythmias could be detected in the same patient. Biventricular pacemakers and cardioverter defibrillators were implanted and applied successfully in the treatment of congestive heart failure for the first time in Hungary. The effect of biventricular pacing on morbidity and mortality, the cost-effectiveness, the exact indication and the combined use with cardioverter defibrillator have yet to be proven in future randomized trials.     

无线寻呼台微波作业人员心电图分析

对某无线寻呼台３２１例微波作业人员进行了心电图（ＥＣＧ）检查与分析。全部受测对象为现职连续６个月以上的寻呼电脑女性操作者（接触组），并以１０７例非接触微波的女性为对照组。结果表明：无线寻呼台电脑机前微波漏能功率密度为２０～５０ｍＷ／ｍ２，均未超标。寻呼台室外环境微波漏能功率密度为２２０～８８０ｍＷ／ｍ２，有一定的微波漏能。接触组ＥＣＧ的异常发生率为２７．７３％，对照组为１１．２１％，有非常显著性差异（Ｐ＜０．０１）。经分析发现接触组中窦性心律不齐发生率（１９．３６％）明显高于对照组（５．６０％），Ｐ＜０．０１；接触组Ｐ－Ｒ间期（０．１５５４±０．０２１１）ｍｓ较对照组（０．１４８±０．０２２７）ｍｓ延长，Ｐ＜０．０１。其余心率、ＱＲＳ间期、Ｑ－Ｔ间期的数值以及窦性心动过缓、窦性心动过速和心电轴左偏等发生率，两组之间均无差异（Ｐ＞０．０５）。结果提示：无线寻呼台电脑操作人员长期接触低强度微波，可导致机体植物神经功能紊乱，从而出现窦性心率不齐的改变。     

Incomplete right bundle branch block and vital capacity.

Right bundle branch block (RBBB) is occasionally encountered in young persons who lack any other evidence of overt cardiac disease (Hiss and Lamb, 1962; Lancaster, Schechter, and Massing, 1972). The block may be complete or incomplete, the latter being more common. Right bundle branch block has been studied in relation to body weight, obesity, serum cholesterol and glucose levels, and blood pressure, but the results have been negative (Ostrander, 1964; Kannel et al., 1962). Data presented here suggest that incomplete RBBB is related to vital capacity.     

The magnetocardiographic diagnosis of right ventricular diastolic overload

The diagnosis of right ventricular overload is often difficult by the electrocardiogram (ECG) when it is associated with right bundle branch block (RBBB). In this study, we examined the usefulness of the MCG in diagnosis of right ventricular diastolic overload and clarified the features of the magnetocardiogram (MCG) of patients with right ventricular overload with RBBB. In our previous studies, we found that MCG criteria shows higher sensitivity in diagnosis of right ventricular hypertrophy, but the criteria showed higher false positivity in patients with RBBB without any underlying disease (RBBB group). Therefore, we set different MCG criteria for right ventricular diastolic overload (RVO-d) as follows based on the mean +/- 2SD of the RBBB group: 1) R wave at C-3 (Rc-3)greater than or equal to 25 x 10(-12)tesla, 2) S wave at F-4 (SF-4)greater than or equal to 11 x 10(-12)tesla. In patients with a right ventricular pressure of more than 50 mmHg, the MCG criteria showed higher sensitivity and specificity than the ECG criteria. These results suggest that the MCG is useful for diagnosis of right ventricular diastolic overload with RBBB.     

Right bundle branch block is not a predictor of coronary artery disease

Right bundle branch block (RBBB) is considered as an important predictor of poor outcome in patients with acute myocardial infarction, but the prognostic implication of RBBB in patients with suspected coronary artery disease (CAD) is unclear. Furthermore, the association between RBBB and incidence of CAD also its influence on the severity of stenosis in coronary arteries has not been established. This study was designed to assess the relationship between RBBB and the presence and the severity of CAD in patients with suspected CAD. The study population consisted of 172 patients with RBBB and 174 patients with normal resting electrocardiography (ECG). Severity of CAD was defined as estimated Gensini score according to the degree, quantity and distribution of lesions in angiographic study. According to our study based on angiographic investigations, in patients with RBBB the prevalence of CAD was 77.3 percent versus 70.1 percent in patients with normal resting ECG (P=0.13). Also, there was no significant association between the presence of RBBB and magnitude of Gensini score (OR=0.87, P=0.62). However, male gender and history of diabetes mellitus were associated with higher Gensini score (OR=3.41; 95% CI: 1.96-5.93, P<0.0001 and OR=3.22; 95% CI: 1.77-5.87, P<0.0001 respectively). This study suggests that although RBBB was associated with more severity of stenosis in left coronary system (LAD&LCX), but as a whole there was no association between RBBB and the presence and severity of CAD.     

Right bundle branch block: Prevalence,incidence, and cardiovascular morbidity and mortality in the general population

Background: Right bundle branch block (RBBB) is among the most common electrocardiographic abnormalities.

Objectives: To establish the prevalence and incidence of RBBB in the general population without cardiovascular events (CVE) and whether RBBB increases cardiovascular morbidity and mortality compared with patients with a normal electrocardiogram (ECG).

Methods: A historical study of two cohorts including 2981 patients from 29 primary health centres without baseline CVE. Cox (for CVE) and logistic (for cardiovascular factors) regression was used to assess their association with RBBB.

Results: Of the patients (58% women; mean age 65.9), 92.2% had a normal ECG, 4.6% incomplete RBBB (iRBBB) and 3.2% complete RBBB (cRBBB). Mean follow-up was five years. Factors associated with appearance of cRBBB were male sex (HR?=?3.8; 95%CI: 2.4–6.1) and age (HR?=?1.05 per year; 95%CI: 1.03–1.08). In a univariate analysis, cRBBB was associated with an increase in all-cause mortality but only bifascicular block (BFB) was significant after adjusting for confounders. cRBBB tended to increase CVE but the results were not statistically significant. Presence of iRBBB was not associated with adverse outcomes. Patients with iRBBB who progressed to cRBBB showed a higher incidence of heart failure and chronic kidney disease.

Conclusion: In this general population cohort with no CV disease, 8% had RBBB, with a higher prevalence among men and elderly patients. Although all-cause mortality and CVE tended to increase in the presence of cRBBB, only BFB showed a statistically significant association with cRBBB. Patients with iRBBB who progressed to cRBBB had a higher incidence of CVE. We detected no effect of iRBBB on morbidity and mortality.     

偏心型封堵器介入治疗嵴内型室间隔缺损临床应用及中期疗效

目的 探讨国产偏心型封堵器介入治疗嵴内型室间隔缺损(VSD)的安全性及中期疗效.方法 2005年1月至2008年7月采用国产偏心型封堵器对26例嵴内型VSD患者行介入治疗.经胸超声心动图提示VSD破口直径3～9mm,平均(4.7±4.5)mm.距肺动脉瓣>2mm,距主动脉瓣>1 mm,并分别于术后1周、1个月、3个月、6个月及12个月进行随访.结果 26例患者中21例封堵成功,5例失败,成功率为80.8%.术后即刻左室造影示少量残余分流2例,微量残余分流3例,均在术后1 d至3个月消失,术后即刻新发完全性左束支传导阻滞(LBBB)1例,余无其他严重并发症发生.封堵术后1周左房内径、左室舒张末期内径即明显缩小(P<0.01),左室收缩末期内径无明显变化,术后1个月及以上各项指标与术后1周比较差异无统计学意义.所有患者均获得随访,随访时间12～48个月.术前合并8例右束支传导阻滞(RBBB),3例LBBB,5例在术后2～14d恢复正常,6例在出院时未恢复正常,包括4例RBBB,2例LBBB.随访1个月时,1例RBBB恢复正常;随访3个月时,1例RBBB恢复正常,余在随访期间持续存在.结论 应用国产偏心型封堵器治疗嵴内型VSD是安全有效的,近中期效果良好,远期疗效尚需进一步临床观察.     

Familial poisoning by carbon monoxide with different ECG changes

The paper presents the poisoning of a family of three by carbon monoxide, caused by incomplete combustion of butane gas in a central heating system, with various disturbances in conduction and ishaemic changes in the ECG. The father, mother and son were poisoned. The father had increased amylase activity in urine (507 i.u./L) and, a COHb concentration of 4.8%. An ECG registered a temporary block of the left branch of the His bundle and a negative T wave in the III lead, which continued for about two weeks. The mother had a COHb concentration of 6% and an extended PQ interval, whereas the son had 8.5% of COHb in the blood and a transient incomplete block of the right branch of the His bundle. After treatment with pressurised pure oxygen, the symptoms of poisoning disappeared, COHb concentration fell to below 1% and the ECG registered an improvement. During treatment the patients also received an infusion of piracetam.     

Comparison of electrocardiographic findings between Northern and Southern Chinese population samples

BACKGROUND: Cardiovascular disease is rare in China, but there are few data on the prevalence of electrocardiographic (ECG) abnormalities in Chinese populations. METHODS: The ECG surveys were carried out in four Chinese population samples, in a total of 9,666 adults aged 35-54 in Beijing and Guangzhou, China from 1981 to 1984. Twelve-lead resting ECG tracings were coded by the Minnesota Code. RESULTS: Prevalence per 1,000 of abnormal ECG ranged from 77.4 to 209.8, and was higher for men than women and higher for Guangzhou than Beijing. Prevalence per 1,000 of major abnormalities in Guangzhou was 29.8 for men and 78.4 for women, higher than the 18.4 and 29.6 for counterparts in Beijing. The ECG changes attributed in 'Western' populations to coronary heart disease (CHD), such as large Q waves (Minnesota Code 1-1, 1-2) and ST-T abnormalities, were similar between Beijing and Guangzhou men, but Guangzhou women had much higher prevalence of ST-T abnormalities than Beijing women. Other ECG abnormalities such as A-V block, left branch bundle block, and left ventricular hypertrophy were rare in people of both sites. CONCLUSIONS: Compared with similar data from the US, these Chinese populations had a relatively low prevalence of ECG abnormalities putatively related to CHD. This corresponds with the low incidence of CHD in the Chinese population. However, within the Chinese populations of this study, a high abnormality rate appeared in a population with low incidence of CHD and hypertension (Guangzhou women). Reasons why ECG abnormalities do not parallel prevalence levels of CHD and hypertension remain to be elucidated.     

Elevated plasma fatty acid concentrations prolong cardiac repolarization in healthy subjects

BACKGROUND: High fatty acid concentrations have been shown to stimulate sympathetic nervous system activity, which may modify ventricular repolarization and thus the Q-T interval on electrocardiogram recordings. OBJECTIVE: The aim of this study was to investigate whether acute elevations of plasma fatty acid concentrations influence the corrected Q-T interval (Q-Tc), Q-Tc dispersion, and sympathetic nervous system activity in healthy nonobese subjects. DESIGN: Thirty-two healthy subjects (x +/- SD: 48+/-7 y of age) received an infusion of 10% triacylglycerol emulsion plus heparin (a bolus of 200 U followed by 0.2 U min(-1) * kg body wt(-1) for 180 min); on another occasion and in random order, the same subjects received a saline infusion. RESULTS: Compared with the saline infusion, infusion of 10% triacylglycerol emulsion increased plasma fatty acids (P<0.001) and was associated with an increase in mean blood pressure (P<0.05), heart rate (P<0.05), Q-Tc (P<0.01), Q-Tc dispersion (P<0.01), and plasma epinephrine (P<0.005). Furthermore, individual changes in plasma epinephrine correlated with changes in Q-Tc (r = 0.60, P<0.001) and Q-Tc dispersion (r = 0.53, P< 0.02) even after adjustment for age, sex, and body mass index (P<0.03 for all correlations). Only changes in plasma fatty acids (P = 0.04) and plasma epinephrine (P = 0.006) concentrations were significantly and independently associated with the lengthening of the Q-T interval. CONCLUSION: Our study showed that elevated plasma fatty acid concentrations might affect cardiac repolarization, at least in part because of an increase in plasma catecholamines.     

高频稳态噪声对心血管系统影响的调查

目的 观察高频稳态噪声对心血管系统的影响。方法 测量噪声作业女工的血压、心率、心律、QRS间期、ST段改变、Q—T间期等参数。结果 工龄小于15年的噪声组窦性心动过速、窦性心律不齐、束支传导阻滞与对照组比较差异有显著性，血压升高及其他心电图参数变化不明显；工龄大于和等于15年噪声组窦性心动过缓，血压升高、QRS时间延长、ST段改变、Q—T间期延长、左心室高电压与对照组比较差异有显著性。结论 接触高频稳态噪声可对心血管系统产生不良影响，影响的范围和程度与接触时间有关。     

卡托普利对接振家兔神经功能的影响

目的探讨卡托普利对接振家兔神经功能的影响及意义。方法将家兔分为接振组、干预组和对照组,对接振组和干预组进行接振试验,干预组从接振第11天起给予卡托普利。于接振试验前后对各组家兔进行体感诱发电位(SEP)及坐骨神经运动传导功能(MCF)的测定。结果接振组N1波、P1波、N2波的潜伏期分别为(30.76±4.26)、(41.91±6.67)、(45.29±5.81)ms,干预组分别为(27.00±3.04)、(35.07±4.20)、(41.15±3.19)ms。与接振试验前及试验后干预组、对照组比较,接振组SEP各波潜伏时明显延长,差异有统计学意义(P<0.05,P<0.01)。接振组坐骨神经运动传导速度、远端波幅、远端潜伏时分别为(35.69±4.37)ms、(1.55±0.73)μV、(8.16±0.71)ms,干预组分别为(52.20±5.13)ms、(2.89±0.36)μV、(7.26±0.77)ms。干预组较接振组坐骨神经运动传导速度、远端波幅明显延长,远端潜伏时均明显减小,差异均有统计学意义(P<0.01)。结论卡托普利对接振家兔神经功能的损伤有一定的改善作用。     

Copper deficiency in a genetically hypertensive cardiomyopathic rat: electrocardiogram, functional and ultrastructural aspects

The effect of copper deficiency on cardiac function and structure was studied in a strain of rats (SHHS/Mcc-cp) known to develop cardiac failure as adults. Restriction of dietary copper (less than or equal to 1 mg/kg vs. 6 mg/kg in adequate diets) at weaning in both sexes for a 6-wk period produced cardiac hypertrophy. Male rats developed more severe copper-deficiency symptoms than their female counterparts. In both sexes of copper-deficient rats, there was an increase in cardiac length, width, free ventricular wall thickness and septum thickness. Electrocardiographic tracings revealed greater QRS height among male copper-deficient rats. Heart rate also was substantially reduced in this group. The increased volume of myocardium occupied by mitochondria in the copper-deficient male rats might result in increased electrical resistance that would increase the QRS height; hypertrophy or anemia also could be contributory. Some male copper-deficient rats had prolongation of the QRS in a bundle branch block pattern. Maximal rates of rise and fall for left ventricular pressure were reduced in male copper-deficient rats. The gross histology indicated that this type of heart failure was more concentric than eccentric. The copper-deficient male rat may serve as a useful model for studying the concentric cardiac hypertrophy that occurs in humans.     

Electrocardiographic abnormalities among arsenic-exposed persons through groundwater in Bangladesh

This study was carried out among arsenic-exposed and non-exposed people of Bangladesh to assess and compare their cardiac status based on electrocardiographic (ECG) findings. For the purpose of the study, participants were included in three groups: arsenic-exposed persons with arsenicosis (arsenicosis group), arsenic-exposed persons without arsenicosis (non-arsenicosis group), and persons not exposed to arsenic (non-exposed group). Each group included 50 respondents. In this study, no significant difference in heart rate, rhythm, axis, and pulse rate interval was detected among the arsenicosis, non-arsenicosis and non-exposed groups. A significant difference in corrected QT interval between the arsenicosis and the non-exposed group (p<0.05) was observed. On the contrary, no statistically significant difference in corrected QT interval between the non-arsenicosis and the non-exposed group was found. Abnormal QRS complex was found among 14%, 8%, and 2% of the arsenicosis, non-arsenicosis, and non-exposed groups respectively. ECG findings, indicative of left ventricular hypertrophy, ischaemic heart disease, and right bundle branch block, were high among the arsenicosis group. Overall, abnormal ECG findings were high (58%) among the respondents of the arsenicosis group and were highly significant (p<0.001). The findings revealed that there was a significant association between ECG abnormalities and arsenic exposure.     

Brugada syndrome

The Brugada syndrome is a clinical-electrocardiographic diagnosis characterised by syncopal or sudden death episodes in patients with a structurally normal heart with a characteristic electrocardiographic pattern consisting of ST segment elevation in the precordial leads V1 to V3 and a morphology of the QRS complex resembling a right bundle branch block. In many patients with the Brugada syndrome, the electrocardiographic manifestations transiently normalize; leading to underdiagnosis of the syndrome. The administration of sodium channel blockers such as ajmaline, flecainide or procainamide accentuate the ST segment elevation and can be used to unmask concealed and intermittent forms of the disease. The incidence of sudden death in this syndrome is very high and can only be prevented by implanting a cardioverter-defibrillator. Because of high incidence of familial occurrence, the extension of the testing to family members is important.     

心电图与早期复极综合征危险分层的相关性研究

目的 探讨心电图对早期复极综合征(ERS)危险分层的价值.方法 将7例有心脏事件(晕厥、猝死及猝死未遂、临床记录心室颤动、电生理诱发心室颤动)的ERS患者、82例无心脏事件的ERS患者及182例健康对照者的心电图QRS时限、T波峰.末间期(TpTe)、校正QT间期(QTc)及QT离散度(QTd)进行比较. 结果有心脏事件的ERS患者、无心脏事件的ERS患者和健康对照者的TpTe分别为(123.3 ±22.4)、(87.7 ±15.5)、(83.5±15.1)ms,有心脏事件的ERS患者TpTe与无心脏事件的ERS患者及健康对照者比较差异均有统计学意义(P<0.05),而无心脏事件的ERS患者的TpTe与健康对照者比较差异无统计学意义.三组QRS时限、QTc及QTd比较差异均无统计学意义(P>0.05).结论 心电图中TpTe可能对ERS患者危险分层有一定价值,但尚需进一步研究证实.     

Cardiovascular mortality predictors in the oldest old

This article investigates the association between cardiovascular risk factors and cardiovascular morbidity and mortality in the oldest old. In 1996, 91% of the population > or = 80 years of age from Veranópolis, Rio Grande do Sul State, Brazil, were evaluated to detect cardiovascular risk factors and morbidity. The sample was followed up for three years, with the assessment of deaths. The analysis was done using univariate statistics and multivariate logistic regression analysis. There were 41 deaths (21%): 20 men and 21 women. Deaths were distributed by year as follow: 03 (7.3%) in the first year, 08 (19.5%) in the second, and 30 (73.2%) in the third. There was a significant and independent association between death and the following variables: diastolic blood pressure (DBP), total cholesterol (TC), LDL-C, ApoA-I, prior stroke (CVA), right bundle branch block (RBBB), and left ventricular hypertrophy (LVH) by ECG. Survivors presented higher levels of DBP, TC, LDL-C, ApoA-I, CVA, RBBB and LVH. According to the multivariate analysis, the variables were independent risk factors for mortality. Cardiovascular risk factors appear to have a distinct impact on the oldest old.     

Protective effects of an aged garlic extract on doxorubicin-induced cardiotoxicity in the mouse

Protective effects of an aged garlic extract on the cardiotoxicity of doxorubicin (DOX) was evaluated using the mouse. DOX (1.5 mg/kg body wt i.p.) was administered three times per week for 40 days. An aged garlic extract, WG-1 (a preserved stock solution; Wakunaga Pharmaceutical) was administered intraperitoneally six times weekly. DOX caused changes in the electrocardiogram. In the control mice, the width of the QRS complex was 20 +/- 2.8 milliseconds, the R-R interval was 130 +/- 2.8 milliseconds, and the P-Q interval was 30 +/- 1.4 milliseconds. In mice treated with DOX for 40 days, the width of the QRS complex was 50 +/- 10 milliseconds (p < 0.05), the R-R interval was 240 +/- 30 milliseconds (p < 0.05), and the P-Q interval was 45 +/- 1.0 milliseconds (p < 0.01). These values were significantly smaller in mice treated with WG-1 + DOX than in mice treated with DOX. The width of the QRS complex was 29.3 +/- 5.8 milliseconds (p < 0.05), the R-R interval was 145.8 +/- 17.9 milliseconds (p < 0.01), and the P-Q interval was 37.8 +/- 3.5 milliseconds (p < 0.05). The lipid peroxidation in the heart homogenates prepared from DOX-treated mice, as measured by thiobarbituric acid-reactive substance (TBARS, nmol malondialdehyde/100 mg protein) was 332.5 +/- 67.0, which was significantly larger than that in the control mice (186.6 +/- 42.2) (p < 0.05). WG-1 decreased the level of TBARS in DOX-treated mice significantly. In the mice treated with WG-1 + DOX, TBARS was 221.3 +/- 31.6, which was significantly smaller than that of DOX-treated mice (p < 0.05). Histological study demonstrated that the heart treated with DOX had vacuolization in muscle cells, disrupted myofibrils, and swollen mitochondria. Mice that received WG-1 + DOX had no significant pathological lesions in the heart.     

对讲机微波辐射对作业人员心电图的影响

目的探讨对讲机微波辐射对作业人员心电图影响。方法于2004年6—7月,选择某企业165名经常使用对讲机的男保安员(工龄为0.5～3.32a)为暴露组,待其使用对讲机后进行心电图检查,另选择该企业80名不使用对讲机的健康男职工(工龄为0.5～3.58a)作为对照组进行心电图检查。结果暴露组窦性心律不齐和窦性心动过缓的百分率、心电图总异常率均高于对照组(P<0.05,P<0.01),暴露组平均心率低于对照组(P<0.01),暴露组P-R间期及Q-T间期比对照组均有延长(P<0.05)。结论该调查中的对讲机使用者心图的改变可能与暴露于对讲机的微波辐射有关。