Focus: The Aging Brain: Neurocardiovascular Instability and Cognition

Neurocardiovascular instability (NCVI) refers to abnormal neural control of the cardiovascular system affecting blood pressure and heart rate behavior. Autonomic dysfunction and impaired cerebral autoregulation in aging contribute to this phenomenon characterized by hypotension and bradyarrhythmia. Ultimately, this increases the risk of falls and syncope in older people. NCVI is common in patients with neurodegenerative disorders including dementia. This review discusses the various syndromes that characterize NCVI icluding hypotension, carotid sinus hypersensitivity, postprandial hypotension and vasovagal syncope and how they may contribute to the aetiology of cognitive decline. Conversely, they may also be a consequence of a common neurodegenerative process. Regardless, recognition of their association is paramount in optimizing management of these patients.     

Diagnostic dilemma of cardiac syncope in pediatric patients

Aims

Syncope is defined as temporary loss of consciousness and postural tone resulting from an abrupt transient decrease in cerebral blood flow. The present work aimed at determining how diagnostic tests are used in the evaluation of pediatric syncope at a tertiary pediatric referral center and to report on the utility and the yield of these tests.

Settings and Design

Retrospective study conducted at a tertiary referral arrhythmolology service

Methods and Material

The clinical charts of 234 pediatric patients presenting with a primary complaint of syncope with an average age of 7.48 ± 3.82(3.5-16) years were reviewed by the investigators.

Statistical analysis used

Statistical Package of social science (SPSS) version 9,0 was used for analysis of data.

Results

The commonest trigger for syncope in the study population was early following exercise (n=65) and the commonest prodrome was palpitation, noted in 25 patients. A murmur was present in 19 of our patients (8.3%) while 10.7% (n=25) had abnormal ECGs. Of the 106 echocardiograms done, 14 (13.2%) were abnormal. Only two of them were missed by ECG. All patients were offered ambulatory 24 hour ECG. One patient with sick sinus syndrome was diagnosed only with Holter.

Conclusions

Clues to the presence of cardiac syncope may include acute onset of syncope, frequent episodes, low difference between blood pressure readings in supine and erect positions (after standing for 2 minutes) and most importantly an abnormal 12 lead ECG. Transthoracic echo and Holter monitoring have low yield in pediatric syncope.     

血浆内皮素配合描记动态脑电图在儿童晕厥诊断中应用的临床意义

摘要 目的：探究血浆内皮素配合描记动态脑电图在儿童晕厥诊断中的应用意义。方法：选择2017年1月至2020年1月于我院接受治疗的83例存在晕厥风险儿童,采集其静脉血样进行血浆内皮素水平测定,并实施动态脑电图检测,而后以倾斜试验结果为金标准,分别分析单纯血浆内皮素、单纯动态脑电图以及血浆内皮素+动态脑电图对晕厥的诊断应用意义。结果：（1）83例入组儿童中阳性为68例,阴性为15例,血浆内皮素检测阳性51例,阴性32例,一致性为77.11 %,灵敏度为73.53 %,特异度为93.33 %,阳性预测值为98.04 %, 阴性预测值为43.75 %;（2）动态脑电图诊断一致性为78.31 %,灵敏度为80.88 %,特异度为66.67 %,阳性预测值为91.67 %,阴性预测值为43.48 %;（3）联合检测诊断一致性为93.98 %,灵敏度为94.12 %,特异度为93.33 %,阳性预测值为98.46 %,阴性预测值为77.78 %;（4）检测方式差异性比较发现,联合检测在一致性、灵敏度、阴性预测值方面明显优于血浆内皮素和动态脑电图检测,在特异度方面优于动态脑电图检测（P<0.05）。结论：血浆内皮素联合描记动态脑电图对儿童晕厥具有较好的诊断辅助价值,能够显著提高诊断的一致性、灵敏度和特异度。     

口服补液盐联合米多君对小儿血管迷走性晕厥的疗效及血清电解质水平、Cor和BNP表达水平的影响

摘要 目的：探究口服补液盐（ORS）联合米多君对小儿血管迷走性晕厥（VVS）的疗效及血清电解质水平、皮质醇（Cor）和脑钠肽（BNP）表达水平的影响。方法：纳入2019年2月至2021年1月于我院儿科就诊的VVS患儿90例作为研究对象,采用随机数字表法将90例患儿随机分为对照组和研究组,每组45例。两组患儿均进行基础健康教育,对照组给予口服盐酸米多君片,研究组在此基础上加服ORS。比较两组患儿的临床疗效、HUTT转阴率、复发率、心率和血压变化、血清电解质水平以及血清Cor和BNP的表达水平变化,并记录研究期间两组患儿所发生的不良反应。结果：研究组总有效率高于对照组（P<0.05）。研究组总转阴率高于对照组,复发率低于对照组（P<0.05）。两组患儿治疗前后HR和SBP均无统计学差异（P＞0.05）。治疗后两组患儿的血清钠、钙、氯的浓度均显著升高,而磷、钾的浓度显著降低（P＜0.05）;与对照组相比,研究组患儿治疗后钠、钙、氯的浓度较高,而磷、钾的浓度较低（P＜0.05）。治疗后两组患儿的血清Cor和BNP的表达水平均显著降低（P＜0.05）;与对照组相比,研究组患儿治疗后均较低（P＜0.05）。两组患儿研究期间均未见明显不良反应。结论：ORS联合盐酸米多君对儿童VVS疗效显著,患儿血清电解质水平显著改善,血清Cor和BNP的表达水平均显著降低,且无明显不良反应,该治疗方案具有一定的实际应用价值。     

人体急性缺氧型循环代偿功能障碍

青年健康受试者89名,取安静坐位。在低压舱3、4、5、6、7千米模拟高度上停留30～120分钟,运用代偿率Z值和障碍度S对循环各指标进行综合性定量评定。循环障碍仅发生于5,000与6,000米,发生率分别为28.9％与55.0％。主要表现特征是心率锐减,血压急降,代偿率低达障碍水平Z≤-20以下,大多数障碍者伴有心律紊乱,严重时伴有苍白、恶心、冷汗与无力等。均属生理性障碍。吸入氧气后迅速消除。产生机理设想为高层次脑中枢首先调节失常,进而导致植物神经功能紊乱,由正常的交感神经占优势转为迷走神经张力过度增强,致使循环代偿功能随之障碍。     

Leadless pacing in a young patient with cardioinhibitory vasovagal syncope

Vasovagal syncope is characterized by vasodilatation and/or bradycardia and thereby a fall in arterial BP and global cerebral perfusion in response to a trigger. Although it is a benign condition, patients with frequent and traumatic episodes need treatment in order to improve quality of life. We describe the case of a 17-years-old boy suffering from cardioinhibitory syncope. At the end of a complete negative cardiac and neurological examination, a loop recorder was implanted. During the subsequent follow-up the ILR documented a 9-s pause. To improve the patient's compliance, and considering cardioinhibitory syncope as a temporary condition, a leadless pacemaker was eventually implanted.     

Tilt-table testing of patients with pacemaker and recurrent syncope

The diagnosis of recurrent syncope in patients with pacemakers (PM) is quite challenging and the etiology of syncope is often multifactorial. To portray the mechanism of syncope in PM patients, we report the results of head-up tilt table testing (HUT) in a series of patients with PM, originally implanted for reasons other than neurally mediated syncope, referred due to syncope or pre-syncope (aborted syncope, vertigo, suspected orthostatic hypotension).Forty-one patients with PM undergoing a HUT in our syncope unit between January 1st, 2007 and December 31st 2011 were included. A standard HUT protocol with nitroglycerine provocation was used and the test results were classified according to current guidelines. Baseline data were retrieved from the medical records.Overall, 54% of patients had a positive response to HUT. Vasodepressor or orthostatic hypotensive response were the most prevalent responses accounting for 72% of patients with a positive test. There were no differences between groups with positive or negative test result regarding age, gender, resting blood pressure and heart rate, daily fluid intake, pacing mode, pacing indication or pacing rhythm at rest.HUT in patients with pacemakers has a high diagnostic yield. Although, the majority of patients had a vasodepressor or orthostatic hypotensive response, cardioinhibitory response leading to syncope was also seen.     

Usefulness of tilt testing in children with syncope: a survey of pediatric electrophysiologists

The role of tilt table testing as a diagnostic modality in children with unexplained syncope is unclear. We sent a questionnaire to members of the Pediatric and Congenital Electrophysiology Society to assess the current practice pattern. Of the 186 members, 97 (52%) replied. Twenty four percent of the pediatric electrophysiologists have completely stopped doing tilt table tests and of those performing the tests, a majority (76%) did < 10 tests/yr (median=3 tilts/yr, range 0-100/yr). Of those performing the test, 95% rarely or never accepted direct referrals from the general practioners and 62% felt that the frequency of tilt table tests being performed had decreased since they had started practicing. The median usefulness of the test was rated at 3 (range 1-9) on a scale of 1 to 10 with 10 being very useful. A majority (68%) felt they rarely or never altered treatment based on the results of the tilt test. Wide variability was noted in the test protocol including the tilt angle, tilt duration, use of pharmacologic agents and the duration of fasting prior to the test. We therefore conclude that there is significant lack of standardization in tilt table tests performed in children. Tilt table testing, as perceived by pediatric electrophysiologists, is of limited utility and progressively less used in children with syncope.