血管迷走性晕厥儿童在直立倾斜试验中同步十二导联心电图P波ST段及T波的动态变化

目的 探讨血管迷走性晕厥(WS)儿童直立倾斜试验(HUTT)中自主神经功能变化,深化儿童VVS的发病机制.方法选择2006-10～2007-10在中南大学湘雅二医院儿童晕厥专科门诊就诊或住院的不明原因晕厥(UPS)儿童96例,根据HUTT结果将研究组分为HUTT阳性组和HUTT阴性组.选取年龄、性别匹配的健康儿童28例作为对照组.研究组和对照组均行HUTF检查,HUTT过程中同时行12导联心电图(12 ECG)动态监测.结果①57例HUTT阳性儿童中,13例表现为基础直立倾斜试验(BHUT)阳性,平均反应时间(24.62±5.94)min;44例表现为舌下含化硝酸甘油倾斜试验(SNHUT)阳性,平均反应时间(5.27±1.89)min.②SNHUT阶段1 min时HUTT阳性组Ⅲ、aVL、aVF导联P波振幅较HUTT阴性组显著升高(P<0.05),其余时间段两组比较差异无统计学意义(P>0.05).③研究组在HUTT中某些导联T波及ST段振幅较对照组显著降低(P<0.05),主要表现在V3、V4、V5及V6导联;HUTT阳性组在HUTT中某些导联T波、ST段振幅较HUTT阴性组显著降低(P<0.05),主要表现在Ⅱ、Ⅲ、aVR、aVL及aVF导联,多发生在HUTF阳性发作平均时间点.④HUTY阳性组晕厥发作时较基础平卧位时P波时间、QRS时间、QT间期显著缩短(P<0.05,P<0.01);与倾斜开始比较,P波时间显著缩短(P<0.05);与倾斜5 min时比较,各指标无显著变化(P>0.05);与试验结束电动倾斜床刚平放时比较,QT间期显著缩短(P<0.01),而QTc间期显著延长(P<0.05).结论VVS儿童存在心脏自主神经功能改变,12 ECG T波及ST段振幅变化较P波振幅变化更敏感.     

直立倾斜试验对不明原因头晕与晕厥患者诊断比较

目的探讨直立倾斜试验(HUTT)对不明原因头晕与晕厥患者诊断上的差异。方法对头晕组(n=35)进行HUTT检查,并选择同期晕厥组(n=303)的HUTT结果为对照,HUTT采用基础直立倾斜试验(BHUT)及舌下含服硝酸甘油倾斜试验(SNHUT)。结果①头晕组与晕厥组患者在BHUT、SNHUT时收缩压、舒张压、心率比较差异无显著性意义(P>0.05),阳性结果反应类型比较差异亦无显著性意义(P>0.05)。②阳性率:HUTT时头晕组31.43%(11/35),晕厥组42.90%(130/303)。其中BHUT时头晕组28.57%(8/28),晕厥组33.82%(70/207);SNHUT时头晕组42.86%(3/7),晕厥组62.50%(60/96)。阳性率在头晕组和晕厥组比较差异无显著性意义(P>0.05)。两组SNHUT阳性率较BHUT均明显提高(P<0.05)。③出现阳性结果时间:BHUT时头晕组(29.13±11.01 min)仅比晕厥组(23.52±12.80 min)稍长,SNHUT时在舌下含服硝酸甘油后也是头晕组(6.00±3.61 min)比晕厥组(4.98±3.51 min)稍长(P均>0.05)。结论临床上部分不明原因头晕患者由VVS所致,但并不出现晕厥发作,这类患者应重视倾斜试验检查。     

血管迷走性晕厥儿童心电图aVR导联T波振幅变化

目的 探讨血管迷走性晕厥(VVS)儿童卧位、立位心电图aVR导联T波振幅变化的意义.方法 选择直立倾斜试验(HUTT)阳性的VVS患儿76例为研究组,年龄4～17岁,平均(11.06±2.37)岁.用SR-1000A心电综合自动分析仪描记卧位及立位12导联同步体表心电图,匹配健康儿童55例为对照组.选择波形清晰的窦性心律3个心动周期,测量aVR导联3个心动周期T波振幅取其平均值.结果 ①心电图aVR导联T波振幅(TaVR)在卧位时两组比较差异无统计学意义(P>0.05),立位时在研究组明显降低(P＜0.05);两组均表现为女性较男性降低(P＜0.05).②aVR导联卧位、立位T波振幅差在研究组大于对照组(P＜0.05);在对照组女性变化较男性明显(P＜0.05),在研究组未显示性别差异(P>0.05);在晕厥频次之间的差异无统计学意义(P>0.05).③研究组中血管抑制型较其他类型(心脏抑制型及混合型)TaVR在卧位、立位时及卧位、立位T波振幅差均无统计学意义(P＜0.05).结论 卧位、立位体位变化可引起TaVR变化,表明TaVR对心脏自主神经功能评价具有指导价值,但TaVR对VVS复发没有预测价值.     

盐酸米多君和美托洛尔对儿童血管迷走性晕厥的干预研究

目的 探讨盐酸米多君和美托洛尔对儿童血管迷走性晕厥(VVS)的干预效果.方法 2003-01～2007-04在中南大学湘雅二医院晕厥专科门诊就诊或住院的不明原因晕厥或晕厥先兆儿童51例,男17例,女34例,年龄6.92～18岁,平均(11.95±2.56)岁,随机给予盐酸米多君和美托洛尔治疗,治疗后2～4周复诊.其中46例患儿服药前后经过直立倾斜试验(HUTT)检查.结果 ①临床主观疗效:盐酸米多君组有效率与美托洛尔组比较筹异无统计学意义(73.91%vs 89.29%,P＞0.05).②HUTT监测客观疗效:盐酸米多君组有效率较美托洛尔组低(54.54%vs70.83%,P＜0.05).HUTT复查可见反应类型发生转变.两组服药前后HUTT各时间点的血流动力学指标(心率、收缩压、舒张压)比较差异无统计学意义(P＞0.05).③药物副反应:盐酸米多君组未见明显副反应,美托洛尔组10.71%出现胃部不适、头痛等副反应.结论 盐酸米多君和美托洛尔对儿童VVS治疗有效,但临床主观疗效未见筹异,用HUTT客观评价则后者有效率高,表明儿童VVS疗效判断HUTT优于主观效果,两药在儿童临床应用中是安全的.     

盐酸米多君对儿童血管迷走性晕厥血流动力学的影响

目的 观察盐酸米多君干预前后血管迷走性晕厥(VVS)儿童血流动力学变化,探讨盐酸米多君对VVS患儿血流动力学的影响.方法 2007-04～2009-05在中南大学湘雅二医院儿童晕厥专科就诊或住院的6～17岁[平均(11.60±2.83)岁]62例不明原因晕厥(UPS)或晕厥先兆、直立倾斜试验(HUTT)阳性的VVS患儿,分为口服补液盐组(n=36)和盐酸米多君组(n=26),根据HUTT结果评价疗效并监测其血流动力学变化.治疗6个月后,如没有晕厥或晕厥先兆发作则停药并继续随访.结果 盐酸米多君组HUTT转阴率与口服补液盐组比较差异无统计学意义(P>0.05);盐酸米多君组晕厥及晕厥先兆复发率低于口服补液盐组(P<0.05);两组干预前后平卧位血压和心率比较差异无统计学意义(P>0.05).盐酸米多君组干预后血压差值(△舒张压)在倾斜起始较基础平卧位显著缩小(P<0.05).结论 盐酸米多君可减少VVS儿童体位改变时血流动力学变化,改善直立不耐受症状.     

儿童血管迷走性晕厥与抑郁的关系

目的 探讨儿童血管迷走性晕厥(ws)与抑郁的关系.方法 2007-06～2007-11月在中南大学湘雅二医院儿童晕厥专科门诊就诊或住院的不明原因晕厥(USP)或先兆晕厥儿童84例,经直立倾斜试验(HUTT)检查诊断为VVS,男47例,女37例,年龄7～16岁,平均(11.01±2.00)岁.将VVS儿童分为HUTT阴性组(n=41)和HuTr阳性组(n=43),再将HUTT阳性组儿童依临床症状分为头晕组与晕厥组.所有受试儿童完成儿童抑郁障碍自评量表(DSRSC),用统计软件SPSS11.0进行数据分析.结果 ①"盼望美好事物"和"容易高兴起来"HUTT阳性组高于阴性组(P<0.01),"生活没意思"HUTT阳性组低于阴性组(P<0.05).②"盼望美好事物"、"肚子痛"及"感到烦恼"得分HUTT阳性组高于常模组(P<0.05或P<0.01),"吃东西香"得分HUTT阳性组低于常模组(P<0.05).③"盼望美好事物"、"睡得很香"、"对自己有信心"和"容易高兴起来"得分HUTT阴性组低于常模组(P<0.05或P<0.01),"总是想哭"、"生活没意思"、"感到烦恼"得分及抑郁总分HUTT阴性组高于常模组(P<0.05).④HUTT阳性儿童"盼望美好事物"和"容易高兴起来"得分头晕组高于晕厥组(P<0.05).结论 ①儿童VVS抑郁发生率高.②VVS儿童较健康儿童食欲减少,躯体化症状、烦恼、抑郁情绪及信心丧失增多.③HUTT阳性儿童中,头晕组较晕厥组对生活更为乐观和积极.以上提示心理因素如抑郁在儿童VVS发生、发展、治疗及预后中可能起重要作用.     

硝酸甘油直立倾斜试验诊断血管迷走性晕厥的价值

目的探讨硝酸甘油直立倾斜试验(sublingual nitroglycerin head-up tilt test,SNHUT)在血管迷走性晕厥(vasovagal syncope,VVS)诊断中的价值。方法拟诊VVS患者59例为观察组,21例健康志愿者为对照组,均行基础直立倾斜试验(basic head-up tilt test,BHUT),无阳性反应者舌下含化硝酸甘油片0.3 mg后继续行SNHUT,比较2组BHUT、SNHUT诱发晕厥时间及阳性率。结果观察组BHUT诱发晕厥时间[(25.31±11.75)min]较SNHUT长[(5.32±3.67)min](P0.05);对照组BHUT未诱发晕厥,SNHUT诱发晕厥时间为[(5.87±3.38)min];观察组SNHUT诱发晕厥时间与对照组比较差异无统计学意义(P0.05);观察组BHUT试验阳性率(15.25%)低于SNHUT试验(76.00%)(P0.05);对照组BHUT试验阳性率(0)低于SNHUT试验(9.52%),差异有统计学意义(P0.05);观察组SNHUT出现窦性停搏1例,经治疗后恢复窦性心律,余无严重不良反应发生。结论 BHUT试验无阳性反应者行SNHUT试验可提高VVS诊断阳性率。     

儿童血管迷走性晕厥临床特征与直立倾斜试验结果的关系

目的 研究儿童血管迷走性晕厥(VVS)临床特征与直立倾斜试验(HUTT)结果的关系,探讨临床特征对儿童HUTT结果的预测价值.方法 2009-01～2009-12在中南大学湘雅二医院儿科晕厥专科就诊或住院的4～17岁[平均(10.36±2.67)岁]226例表现为不明原因晕厥、头晕、头痛、心慌或心悸等症状的儿童,详细收集患儿的年龄、性别、晕厥史、晕厥次数、临床表现、晕厥家族史等临床特征,行HUTT检查.结果 ①临床表现:HUTT阳性组124例,HUTT阴性组102例.HUTT阳性组常见临床表现依次为头晕或头痛(67.74%)、晕厥(44.35%)、胸闷(25%)及面色苍白(12.90%).HUTT阴性组常见临床表现依次为头晕或头痛(68.65%)、晕厥(21.56%)、胸闷(16.67%)、面色苍白(10.78%).②HUTT阳性率:＞12岁组患儿显著高于≤12岁组(79.55% vs 49.44%,P<0.01);女性组显著高于男性组(61.61% vs 48.25%,P<0.05);有晕厥史组显著高于无晕厥史组(71.05% vs 46.67%,P<0.05);晕厥1～2次组、晕厥3～4次组及晕厥5～10次组三组比较差异无统计学意义(P>0.05);有晕厥家族史组显著高于无显著晕厥家族史组(71.43% vs 49.41%,P<0.01).③HUTT反应类型:124例HUTT阳性患儿中,27例为基础直立倾斜试验(BHUT,血管抑制型20例,混合型7例),97例为舌下含化硝酸甘油倾斜试验(SHNUT,血管抑制型86例,混合型11例).④Logistic回归分析显示,对HUTT结果有显著影响的临床特征依次为年龄、晕厥家族史及晕厥史.结论 VVS患儿年龄、晕厥家族史及晕厥史等临床特征对预测HUTT结果有显著影响.     

血管迷走性晕厥患者与身高体质量及人体质量指数的关系

目的 探讨血管迷走性晕厥(VVS)患者与身高、体质量及人体质量指数(BMI)的关系.方法 2001-01-2007-08在中南大学湘雅二医院晕厥专科门诊就诊或住院的不明原因晕厥(UPS)或先兆晕厥患者418例,经直立倾斜试验(HUTT)检查阳性诊断为VVS,其中4-17岁[平均(11.37±2.99)岁]223例(儿童组),18～70岁[平均(36.82±13.64)岁]195例(成人组).测量身高、体质量,计算BMI.结果 成人组HUTT阳性患者、HUTT阴性患者BMI在头晕组稍高于晕厥组(P＞0.05);HUTT阴性组较HUTT阳性组BMI及体质量明显增高(P＜0.01),两组身高比较差异无统计学意义(P＞0.05).儿童组BMI在各年龄段HUTT阴性组与HUTT阳性组比较差异均无统计学意义(P＞0.05).儿童HUTT阳性组或HUTT阴性组BMI与年龄均呈直线相关,两组直线回归显示,16岁以下儿童BMI在HUTT阴性组高于HUTT阳性组,16岁以上则呈相反变化.结论 成人低体质量和低BMI者晕厥易感性增加,儿童BMI与晕厥易感性相关不密切.     

口服补液盐治疗血管迷走性晕厥疗效及与血流动力学类型的关系

目的观察口服补液盐治疗血管迷走性晕厥(VVS)的临床疗效,并评价其对不同血流动力学类型VVS患者的影响。方法采用前瞻性研究方法,选择2013年9月至2016年6月东莞东华医院收治的80例VVS患者作为研究对象,采用随机数字表法随机分为两组,对照组(n=25)给予健康教育,观察组(n=55)在健康教育基础上给予口服补液盐治疗。比较两组患者直立倾斜试验(HUTT)转阴率、平卧血压和心率;另外根据不同血流动力学类型,观察组又分为血管抑制型(n=29)和混合型及心脏抑制型(n=26),观察口服补液盐对不同血流动力学类型VVS患者的影响;对照组和观察组治疗6个月后若无晕厥或晕厥先兆发展则停止治疗并随访12个月,观察晕厥或晕厥先兆复发率。结果治疗6个月后,观察组HUTT转阴率(70.9%)明显高于对照组(24.0%),差异有显著性(P0.05);两组患者治疗前后的平卧血压和心率差异均无统计学意义(P0.05),但两组患者治疗后的HUTT过程中倾斜开始与基础平卧位血压和心率差值的变化差异均有统计学意义(P0.05);随访12个月,观察组的晕厥或晕厥先兆复发率(43.6%)明显低于低于对照组(68.0%),差异有显著性(P0.05);血管抑制型HUTT转阴率(79.3%)、随访晕厥或晕厥先兆复发率(34.5%)略优于混合型及心脏抑制型(61.5%,53.8%),但差异均无统计学意义(P0.05)。结论口服补液盐治疗VVS的疗效要优于单纯健康教育;口服补液盐适用于不同血流动力学类型VVS患者,疗效相似。     

血管迷走性晕厥患者直立倾斜试验反应类型转变的机制

目的 探讨血管迷走性晕厥(VVS)患者直立倾斜试验(HUTT)反应类型发生转变的机制.方法 2003-06～2008-04在我院晕厥专科门诊就诊或住院的以不明原因晕厥或晕厥先兆为主诉的患者50例,年龄7-53岁[平均(14.82±8.55)岁],男性15例,女性35例,HUTT检查为阳性,诊断为VVS.经健康教育与药物干预治疗后,随诊并追踪复查HUTT.HUTT采用基础直立倾斜试验(BHUT)及舌下含化硝酸甘油直立倾斜试验(SNHUT),比较初诊检查与重复检查的HUTr反应类型.结果 第一次HUTT复查50例中有5例(10%)HUTT反应类型发生改变,第二次HuTT复查10例中有2例(20%)HUTT反应类型发生改变.HUTT反应类型发生转变见于心脏抑制型转变为混合型、血管抑制型转变为混合型、混合型转变为心脏抑制型、混合型转变为血管抑制型.结论 VVS患者随访过程中HUTT反应类型可发生转变,HUTT反应类型转变的机制受患者自主神经功能状态、干预治疗方法及患者的耐受性等多因素影响.     

儿童血管迷走性晕厥的诱因与先兆分析

目的探讨儿童血管迷走性晕厥（VVS）诱因与先兆的特点。方法分析55例经直立倾斜试验（HUTT）诊断为VVS儿童的晕厥诱因和先兆症状，对不同性别、不同年龄段（7—11岁及12～18岁）、不同试验方式（BHUT及SNHUT）儿童的晕厥诱固和先兆的有无进行比较。结果74．55％和96．36％的VVS儿童存在晕厥诱因和先兆症状，常见诱固有长久站立（43．64％）、体位改变（20．00％）等；常见先兆症状为头晕（78．18％）、乏力（29．09％）、面色苍白（27.27％）、大汗（27．27％）、心慌（25.45％）、黑朦（23．64％）、胸闷（21．82％）、头痛（21．82％）等。晕厥诱因和先兆的有无在不同性别、年龄段、倾斜试验方式之间比较差异没有显著性（P〉0．05）。结论熟悉儿童VVS诱固和先兆特点将有助于临床诊治。     

Situational syncope: response to head-up tilt testing and follow-up: comparison with vasovagal syncope

Among sequential patients with neurally-mediated syncope, we studied the response to head-up tilt test (HUTT) in patients with situational syncope (SS) and their follow-up. Our findings were compared to those in patients with vasovagal syncope (VVS). The response to HUTT in patients with SS has not to date been fully investigated. Additionally, the prognosis of SS patients has not been systematically studied. We studied 162 consecutive patients with recurrent SS or VVS, all free of structural heart disease. Before study inclusion, they underwent an HUTT and were followed up for 12 months. Patients with SS were advised to avoid the trigger event. Patients with VVS were treated with propranolol or fluoxetine. For each patient we compared the number of syncopal spells during the last 12 months before study inclusion with that during follow-up. Among the 162 patients, 36 had SS and 126 had VVS. The response to HUTT and the number of syncopes before and during follow-up were similar in both groups. Among patients with SS, 10 (28%) had also experienced occasional episodes of VVS; however, they had a similar response to HUTT and prognosis to the remaining 26 SS patients without VVS attacks. Patients with SS have a similar response to HUTT and similarly benign clinical course to patients with VVS. The coexistence of occasional VVS episodes in patients with SS is not associated with a higher rate of positive HUTT or worse prognosis.     

Tilt Testing: Is It Necessary in All Patients with Suspected Vaso‐Vagal Syncope?

BACKGROUND: Head-up tilt testing (HUTT) is a well-established diagnostic tool in patients with suspected vaso-vagal syncope (VVS). However, it is time-consuming and requires special equipment. Thus, identification of simple parameters which could predict the outcome of HUTT could simplify diagnostic steps by obviating the need for HUTT. AIM: To assess which symptoms associated with spontaneous syncope or other details from medical history can predict HUTT results. METHODS: The study group consisted of 202 unselected patients (69 males, mean age 43 +/- 20 years) who were admitted to our syncope unit for HUTT due to suspected VVS. They filled in a detailed questionnaire including 34 standard questions concerning medical history as well as circumstances and symptoms associated with syncopal episodes. Patients were tilted to 70 degrees for 45 minutes or the test was stopped earlier if syncope occurred. A stepwise multiple logistic regression was performed in order to assess which parameters independently predicted the results of HUTT. A point-score was developed by assigning +/-1, +/-2, or +/-3 points to each of the factors based on the relative magnitude of the estimated regression coefficient. The points were then summed and a diagnostic threshold chosen using plots of sensitivity and specificity curves. RESULTS: Syncope was induced by HUTT in 67 (33%) patients. In the whole study group, a point-score identified patients with positive HUTT with a sensitivity of 87.9%, and specificity of 36.3%. When the analysis was confined to the subgroup with >4 syncopal episodes in the past, the sensitivity of a point-score was 94.4%, and specificity--60%, and in the subgroup with >2 syncopal episodes occurring within 1 month preceding HUTT, sensitivity values reached 88.2% at the specificity level of 90.9%. CONCLUSIONS: In patients with frequent syncopal episodes, especially clustered shortly before performing HUTT, in whom symptoms are very suggestive of VVS, a simple point-score system based on medical history accurately predicts HUTT results. Thus, HUTT may not be necessary for establishing diagnosis in this group of patients.     

Early prediction of unexplained syncope by support vector machines

The goal of the present study was to develop and evaluate a new method for the prediction of unexplained syncope occurrences. Diagnosis of syncope is currently based on the reproduction of symptoms in combination with hypotension and bradycardia induced by a 45 min 60-70 degrees head-upright tilt test (HUTT). The main drawback of this widely used test concerns its duration that reaches 55 min if the patient does not faint. Our method is a first step in the avoidance of the HUTT. An electrocardiogram and a transthoracic impedance waveform were recorded for 10 min of supine rest of a HUTT in 128 patients with a history of unexplained recurrent syncope. Seven indices were computed on the transthoracic impedance and its first derivative. The prediction quality of every subset of these variables, mixed with age and sex, has been tested by a support vector machine in a retrospective group of 64 patients (100% of sensitivity and 100% of specificity was reached). The best subset obtained has been evaluated prospectively in a group of 64 patients (94% of sensitivity and 79% of specificity was reached). These results compare very favorably with published results for other unexplained syncope detectors.     

十二导联心电图对左主干病变导致急性冠状动脉综合征的诊断价值

目的探讨十二导联心电图对左主干病变导致急性冠状动脉综合征（ACS）的诊断价值。方法37例ACS患者根据冠状动脉造影结果分为A组（左主干病变导致ACS组）17例和B组（左前降支近段病变导致ACS组）20例,2组患者胸痛发作时均行十二导联心电图检查,分析冠状动脉病变血管与相应心电图变化的关系。结果A组在Ⅱ、Ⅲ、aVF、V2、V3、V4、V5、V6导联上相应ST段压低的发生率高于B组（P〈0．05或P〈0．01）。A组ST段在aVR、V1导联抬高并aVF、V2、V4导联压低发生率高于B组（P〈0．05）。结论十二导联心电图上aVR、V1导联ST段抬高并aVF、V2、V4导联压低对ACS患者左主干病变有较好的阳性预测价值。     

直立不耐受儿童直立倾斜试验的性别和年龄差异

目的 探讨直立不耐受(OI)儿童直立倾斜试验(HUTT)的性别和年龄差异.方法 2004-01～2009-06在中南大学湘雅二医院儿童晕厥专科门诊就诊或住院的具有不明原因晕厥、头晕、胸闷、胸痛或心悸等OI症状的儿童728例,年龄3～17 岁[平均(10.67±2.85)岁],男388例,女340例.其中＜12岁416例,年龄3～11岁[平均(8.69±1.86)岁];≥12岁312例,年龄12～17岁[平均(13.30±1.50)岁].经详细询问病史、体格检查、心脏X线、超声心动图、常规12导联心电图、脑电图、头颅CT、血液生化(空腹血糖、心肌肌钙蛋白I)等排除器质性心脏病及其他疾病后行HUTT检查.结果 ①HUTT阳性率:60.71%(442/728),女性高于男性(P<0.01);≥12岁组高于＜12岁组(P<0.01).HUTT阳性率在＜12岁组男性低于女性(P<0.05),≥12岁组男性与女性比较差异无统计学意义(P＞0.05),≥12岁组男性及女性分别高于＜12岁组男性及女性(P均<0.01).②HUTT类型:以血管迷走性晕厥(VVS)多见(59.95%,265/442),其次为体位性心动过速综合征(POTS,37.56%,166/442)及体位性低血压(OH,2.49%,11/442).HUTT类型分布在男性与女性之间及＜12岁组与≥12岁组之间比较差异均无统计学意义(P均＞0.05).HUTT类型分布在男性及女性＜12岁组与≥12岁组之间比较差异无统计学意义(P均＞0.05).HUTT类型分布在＜12岁组及≥12岁组男性与女性之间比较差异无统计学意义(P均＞0.05).结论 具有不明原因晕厥、头晕、胸闷、胸痛或心悸等OI症状的儿童HUTT阳性率存在性别和年龄差异,但HUTT类型分布未见明显的性别和年龄差异.     

Heart rate variability during sleep in patients with vasovagal syncope

Background: There are a few studies showing no significant heart rate variability (HRV) over a 24-hour period in vasovagal syncope (VVS) patients, but no research has examined HRV and its sympathetic and parasympathetic components during rapid eye movement (REM) and non-REM sleep. The authors hypothesized that REM sleep might be a critical state in which VVS patients would show abnormal responses.
Objectives: To analyze the sympathetic and parasympathetic components of HRV during REM and SWS in patients with VVS compared to normal subjects, and in patients with positive HUTT compared to negative ones.
Methods: Thirty-seven VVS patients and 20 normal age-matched controls were submitted to polysomnography with 24-hour Holter monitoring to assess HRV. Time and frequency domain techniques were carefully performed for 24 hours and during Stages 3 and 4 of REM and non-REM sleep. Variation of sympathetic activity index (VSAI) was defined as the difference in the low frequency (LF) component of HRV between REM and Stages 3 and 4 of non-REM sleep. An analysis of variance was performed to compare patients and controls; patients with positive and negative head-up tilt testing.
Results: The LF component was lower in syncope compared to normal patients (1,769.54 ± 1,738.17, 3,225.37 ± 2,585.05, respectively, P = 0.03). There was a significant decrease in VSAI in the syncope group compared to the control group (−539.39 ± 1,930.78, 1,268.10 ± 2,420.20, respectively, P = 0.01). The other sleep variables analyzed including very LF, high frequency, low frequency/high frequency and time domain parameters did not reach statistical significance. Syncope patients also showed an increase in slow wave sleep (28.2 ± 10.5, 19.7 ± 7.8, P = 0.01).
Conclusions: VVS patients exhibited sympathetic suppression during REM sleep. Possible mechanisms are discussed in this article.     

aVR导联QRS波形态对下壁心肌梗死的鉴别诊断意义

目的 探讨aVR导联QRS波形态对下壁心肌梗死的鉴别诊断意义.方法 分析52例Ⅲ、aVF导联均为病理性Q波患者的aVR导联QRS波形态,并与选择性冠状动脉造影结果对照.结果 aVR导联QRS波呈rS(s)型、QS(qs)型和Q(q)r型的患者分别为13例、10例和29例,三种形态与冠状动脉造影结果比较显示右冠状动脉或左回旋支有狭窄、闭塞病变的患者分别为12例、4例和0例,差异有统计学意义(χ2=35.56,P=0.000).结论 aVR导联QRS波形态对Ⅲ、aVF导联均为病理性Q波患者具有鉴别诊断意义.aVR导联QRS波呈Q(q)r型,可排除陈旧性下壁心肌梗死;aVR导联QRS波呈rS(s)型,可基本确定有陈旧性下壁心肌梗死.