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1.
BackgroundThe aim of the study was to characterize the clinical and electroencephalographic (EEG) patterns associated with tilt-induced reflex syncope and delayed orthostatic hypotension without syncope in youth.MethodsWe conducted a prospective observational study of 95 patients referred to a pediatric neurology clinic for head-upright tilt testing. Clinical signs, symptoms, video EEG, and continuous blood pressure and heart rate were monitored.ResultsEighty patients had reflex syncope, and 15 had delayed-onset hypotension without syncope. The mean age was 15.3 (standard deviation ±2.3) years; 75 (78.9%) were female. All patients with hypotension only had corresponding signs and symptoms; 13 (86.7%) had corresponding EEG slowing. The duration of EEG slowing with hypotension far exceeded the presyncope interval from onset of slowing to loss of consciousness among patients with syncope (P < 0.001). Although prior near-syncope and presyncope episodes were reported commonly in both groups, patients with delayed hypotension without syncope were less likely to have experienced loss of consciousness during episodes of orthostatic intolerance (P < 0.001). Patients with syncope had either slow-flat-slow (n = 23) or slow-only (n = 57) EEG patterns. Compared to those with slow-only EEG patterns, patients with the slow-flat-slow pattern had greater rates of asystole (P < 0.001), myoclonic movements (P < 0.001), facial grimace (P = 0.003), vocalizations (P = 0.002), and arm flexion (P < 0.001) or extension (P = 0.006) during tilt-induced syncope.ConclusionsAmong otherwise healthy youth, orthostatic signs and symptoms vary across the spectrum of tilt-induced reflex syncope and delayed hypotension without syncope. Delayed hypotension without syncope may represent the poorly defined phenomenon of “near syncope” in some patients. 相似文献
2.
Hemodynamic and neurohumoral responses to head-up tilt in patients with chronic fatigue syndrome 总被引:2,自引:0,他引:2
H. J. L. M. Timmers W. Wieling P. M. M. B. Soetekouw G. Bleijenberg J. W. M. van der Meer J. W. M. Lenders 《Clinical autonomic research》2002,12(4):273-280
Background: Data on the prevalence of orthostatic intolerance (OI) in patients with chronic fatigue syndrome (CFS) are limited and controversial.
We tested the hypothesis that a majority of CFS patients exhibit OI during head-up tilt. Methods: Hemodynamic and neurohumoral responses to 40 minutes of head-up tilt were studied in 36 CFS patients and 36 healthy controls.
Changes in stroke volume, cardiac output and peripheral vascular resistance were estimated from finger arterial pressure waveform
analysis (Modelflow). Blood samples were drawn before and at the end of head-up tilt for measurement of plasma catecholamines.
Results: At baseline, supine heart rate was higher in CFS patients (CFS: 66.4 ± 8.4 bpm; controls: 57.4 ± 6.6 bpm; p < 0.001) as was
the plasma epinephrine level (CFS: 0.11 ± 0.07 nmol/l; controls: 0.08 ± 0.07 nmol/l: p = 0.015). An abnormal blood pressure
and/or heart rate response to head-up tilt was seen in 10 (27.8 %) CFS patients (6 presyncope, 2 postural tachycardia, 2 tachycardia
and presyncope) and 6 (16.7 %, p = 0.26) controls (5 presyncope, 1 tachycardia, 2 tachycardia and presyncope). Head-up tilt-negative
CFS patients showed a larger decrease in stroke volume during tilt (−46.9 ± 10.6) than head-up tilt-negative controls (−40.3
± 13.6 %, p = 0.008). Plasma catecholamine responses to head-up tilt did not differ between these groups. Conclusion: Head-up tilt evokes postural tachycardia or (pre)syncope in a minority of CFS patients. The observations in head-up tilt-negative
CFS patients of a higher heart rate at baseline together with a marked decrease in stroke volume in response to head-up tilt
may point to deconditioning.
Received: 20 July 2001, Accepted: 19 February 2002 相似文献
3.
Comparison of the active standing test and head-up tilt test for diagnosis of syncope in childhood and adolescence 总被引:2,自引:0,他引:2
Abstract
We examined 51 children and adolescents with orthostatic symptoms using two orthostatic tests, the active standing test (the AS test) and head-up tilt test (HUT), and compared circulatory responses, autonomic function in addition to the induction rate of syncope during short-time orthostasis. Syncope was induced in eight patients with both tests, in only six patients with the AS test and in only one patient with HUT. The induction rate was significantly higher with the AS test (p<0.0001). In addition, the AS test is common and daily postural motion and does not require a tilt table. We calculated percent changes in systolic blood pressure at the initial drop (ID-SBP), in systolic blood pressure (SBP), in diastolic blood pressure (DBP), in heart rate (HR), component coefficient variation LF/HF (LF/HF) from supine to upright. HR were significantly larger in fainters than in non-fainters with both tests, although there was no difference in SBP and in DBP. In six fainters only with the AS test, HR was significantly larger with the AS test than with HUT. With the AS test ID-SBP were correlative with LF/HF, and LF/HF were correlative with HR, whereas these relations were not clear in HUT. These results indicated the AS test caused cardiac sympathetic activation associated with an initial pressure drop, and was more prone to induce syncope with a greater HR increase in some patients. We conclude the AS test is as potential as HUT as a diagnostic test for syncope. 相似文献
4.
5.
Andrew C. Ertl Ph.D. André Diedrich M.D. Italo Biaggioni M.D. 《Clinical autonomic research》2000,10(5):269-277
Microgravity imposes adaptive changes in the human body. This review focuses on the changes in baroreflex function produced by actual spaceflight, or by experimental models that simulate microgravity, e.g., bed rest. We will analyze separately studies involving baroreflexes arising from carotid sinus and aortic arch afferents (high-pressure baroreceptors), and cardiopulmonary afferents (low-pressure receptors). Studies from unrelated laboratories using different techniques have concluded that actual or simulated exposure to microgravity reduces baroreflex function arising from carotid sinus afferents (carotic-cardiac baroreflex). The techniques used to study the carotid-cardiac baroreflex, using neck suction and compression to simulate changes in blood pressure, have been extensively validated. In contrast, it is more difficult to selectively study aortic arch or cardiopulmonary baroreceptors. Nonetheless, studies that have examined these baroreceptors suggest that microgravity produces the opposite effect, ie, an increase in the gain of aortic arch and cardiopulmonary baroreflexes. Furthermore, most studies have focus on instantaneous changes in heart rate, which almost exclusively examines the vagal limb of the baroreflex. In comparison, there is limited information about the effect of microgravity on sympathetic function. A substantial proportion of subjects exposed to microgravity develop transient orthostatic intolerance. It has been proposed that alterations in baroreflex function play a role in the orthostatic intolerance induced by microgravity. The evidence in favor and against this hypothesis is reviewed. 相似文献
6.
Diogo Reis Carneiro Isabel Rocha Mario Habek Raimund Helbok Johann Sellner Walter Struhal Gregor Wenning Alessandra Fanciulli 《European journal of neurology》2023,30(5):1528-1539
Background
Cardiovascular autonomic dysfunction may reportedly occur after a coronavirus-disease-2019 (COVID-19) infection, but the available evidence is scattered. Here we sought to understand the acute and mid-term effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on cardiovascular autonomic function.Methods
We performed a systematic PubMed, Embase, Web of Science, medRxiv, and bioRxiv search for cases of cardiovascular autonomic dysfunction during an acute SARS-CoV-2 infection or post-COVID-19 condition. The clinical-demographic characteristics of individuals in the acute versus post-COVID-19 phase were compared.Results
We screened 6470 titles and abstracts. Fifty-four full-length articles were included in the data synthesis. One-hundred and thirty-four cases were identified: 81 during the acute SARS-CoV-2 infection (24 thereof diagnosed by history) and 53 in the post-COVID-19 phase. Post-COVID-19 cases were younger than those with cardiovascular autonomic disturbances in the acute SARS-CoV-2 phase (42 vs. 51 years old, p = 0.002) and were more frequently women (68% vs. 49%, p = 0.034). Reflex syncope was the most common cardiovascular autonomic disorder in the acute phase (p = 0.008) and postural orthostatic tachycardia syndrome (POTS) the most frequent diagnosis in individuals with post-COVID-19 orthostatic complaints (p < 0.001). Full recovery was more frequent in individuals with acute versus post-COVID-19 onset of cardiovascular autonomic disturbances (43% vs. 15%, p = 0.002).Conclusions
There is evidence from the scientific literature about different types of cardiovascular autonomic dysfunction developing during and after COVID-19. More data about the prevalence of autonomic disorders associated with a SARS-CoV-2 infection are needed to quantify its impact on human health. 相似文献7.
Jade A. Gehrking Stacy M. Hines Lisa M. Benrud-Larson Tonette L. Opher-Gehrking Phillip A. Low M. D. 《Clinical autonomic research》2005,15(2):71-75
Abstract
Objective
There is uncertainty as to the minimum duration of head-up tilt (HUT) needed to detect orthostatic hypotension (OH). The orthostatic duration has variably been recommended to be 1, 2, 3, and 5 minutes. The purpose of the current study was 1) to determine the minimum duration of HUT necessary to detect OH and 2) to identify different patterns of orthostatic blood pressure (BP) response in patients with OH.
Design/methods
We evaluated the medical records of 66 consecutive patients (mean age 70.0±10.1 years; 64% male) seen at Mayo Clinic-Rochester from 2000–2001 who fulfilled the criteria for OH (systolic blood pressure [SBP] reduction 20mm Hg within 3 minutes of HUT) during routine clinical autonomic studies. All patients completed an autonomic reflex screen with continuous monitoring of heart rate and BP during supine rest and 5 minutes of 70 degree HUT. Severity of autonomic deficits was quantified with the Composite Autonomic Severity Score (CASS).
Results
Overall, BP was the lowest at 1 minute with gradual and partial recovery over the following 4 minutes. Eighty-eight percent of patients (N=58) developed OH by 1 minute of HUT, with an additional 11% (N=7) developing OH by 2 minutes and the remaining 1% (N=1) developing OH by 3 minutes. We identified two broad patterns of SBP response to HUT. Forty-eight percent (N=32) of patients demonstrated an initial drop in SBP ( 20 mm Hg),which remained stable until tilt-back. Thirty-six percent (N=24) demonstrated an initial drop ( 20mm Hg) followed by a progressive decline in SBP until tilt-back. Repeated measures analysis of variance confirmed that the SBP change in response to HUT differed significantly among patients with a stable vs. progressive pattern [F(3,32)=25.1, p<0.001). Patients with the progressive pattern also had more severe adrenergic impairment on the CASS (p=0.03) and were more likely to have their tilt test terminated early (prior to 5minutes) due to presyncope (p<0.0001) than patients with the stable pattern.
Conclusions
One minute of HUT will detect OH in the great majority (88%) of patients and three minutes will detect the balance. Orthostatic stress beyond 2 minutes is necessary to detect the pattern of progressive OH. Since this group has more severe adrenergic deficits than the group with stable OH, we suggest that the progressive pattern is due to greater impairment of compensatory reflexes. Recognition of the group with progressive fall in BP is important since this group may be at greater risk of orthostatic syncope. 相似文献
8.
Kenneth A. Mayuga MD Katherine B. Butters CNMT Fetnat Fouad-Tarazi MD 《Clinical autonomic research》2008,18(3):155-157
Postural tachycardia syndrome (POTS) involves an HR-rise within 10 minutes of head-up tilt. Hypokinetic circulation, older age, and ACE-inhibitor or Angiotensin-Receptor Blockers were associated with "Late" POTS (after 10 minutes of tilt) versus "Early" POTS (within 10 minutes of tilt). 相似文献
9.
10.
Paola Sandroni Tonette L. Opfer-Gehrking Wolfgang Singer Phillip A. Low 《Clinical autonomic research》2005,15(1):51-53
Abstract
We report the result of a follow-up, open-label study of pyridostigmine for treatment of orthostatic hypotension. Aim of the study was to evaluate self-reported efficacy and patients satisfaction with the medication. Most patients were very satisfied with the medication and chose to continue it.This study was supported in part from grants from the National Institutes of Health, Bethesda, MD: 5 K23 RR15537 (Dr. Sandroni), NS3 2352, NS4 4233 NS4 3364 (Dr. Low), and Mayo GCRC grant M01-RR00585 相似文献
11.
Dr David H. P. Streeten MB DPhil FRCP Gunnar H. Anderson Jr. 《Clinical autonomic research》1998,8(2):119-124
Past studies have shown that severe fatigue was the presenting symptom in six of seven patients with delayed orthostatic hypotension and that tilt table-induced hypotension was found in 22 of 23 patients with the chronic fatigue syndrome. We have determined the prevalence of fatigue, volunteered in response to a nonspecific pre-examination questionnaire used in 431 patients, each subsequently diagnosed as having one of eight neurological or endocrine disorders. The results show that fatigue is a very common symptom in patients with delayed orthostatic hypotension (n=21), as well as both primary (n=30) and secondary (n=106) hypocortisolism: 70–83% in all groups. In contrast, fatigue was an uncommon complaint in patients with multiple system atrophy (MSA) (n=30), pituitary dosorders without hypocortisolism (n=106) or idiopathic hirsutism (n=96): 7–33% in all groups, and was intermediate in prevalence in patients with acute hyperadrenergic orthostatic hypotension (n=32): 41%. It is concluded that fatigue commonly results from delayed orthostatic hypotension and all forms of hypocortisolism but is less common in patients with acute orthostatic hypotension, both idiopathic and due to MSA, which more commonly present with lightheadedness or syncope. 相似文献
12.
After a reversible right hemispheric stroke, a patient with bilateral carotid occlusion developed left motor seizures and bilateral TIAs, both triggered by orthostatic hypotension.
A CT-scan showed a right frontal hypodense area. Hemodynamic factors may cause focal seizures in patients with cortical lesions.
Riassunto Dopo un attacco ischemico reversibile in emisfero destro, un paziente con occlusione carotidea bilaterale presentò crisi epilettiche focali motorie agli arti di sinistra e TIA bilaterali, entrambi scatenati da ipotensione ortostatica. Una TAC dimostrò un 'area ipodensa frontale destra. Fattori emodinamici possono provocare crisi epilettiche focali in pazienti con lesioni corticali.相似文献
13.
Alessandra Fanciulli Fabian Leys Magdalena Krbot Skorić Diogo Reis Carneiro Giovanna Calandra-Buonaura Jennifer Camaradou Giacomo Chiaro Pietro Cortelli Cristian Falup-Pecurariu Roberta Granata Pietro Guaraldi Raimund Helbok Max J. Hilz Valeria Iodice Jens Jordan Evert C. A. Kaal Anita Kamondi Anne Pavy Le Traon Isabel Rocha Johann Sellner Jean Michel Senard Astrid Terkelsen Gregor K. Wenning Elena Moro Thomas Berger Roland D. Thijs Walter Struhal Mario Habek the Collaborators of European Network of Neurological ANS laboratories 《European journal of neurology》2023,30(6):1712-1726
Background and purpose
The objective was to investigate the impact of the coronavirus disease 2019 (COVID-19) pandemic on European clinical autonomic practice.Methods
Eighty-four neurology-driven or interdisciplinary autonomic centers in 22 European countries were invited to fill in a web-based survey between September and November 2021.Results
Forty-six centers completed the survey (55%). During the first pandemic year, the number of performed tilt-table tests, autonomic outpatient and inpatient visits decreased respectively by 50%, 45% and 53%, and every third center reported major adverse events due to postponed examinations or visits. The most frequent newly diagnosed or worsened cardiovascular autonomic disorders after COVID-19 infection included postural orthostatic tachycardia syndrome, orthostatic hypotension and recurrent vasovagal syncope, deemed to be likely related to the infection by ≥50% of the responders. Forty-seven percent of the responders also reported about people with new onset of orthostatic intolerance but negative tilt-table findings, and 16% about people with psychogenic pseudosyncope after COVID-19. Most patients were treated non-pharmacologically and symptomatic recovery at follow-up was observed in ≥45% of cases. By contrast, low frequencies of newly diagnosed cardiovascular autonomic disorders following COVID-19 vaccination were reported, most frequently postural orthostatic tachycardia syndrome and recurrent vasovagal syncope, and most of the responders judged a causal association unlikely. Non-pharmacological measures were the preferred treatment choice, with 50%–100% recovery rates at follow-up.Conclusions
Cardiovascular autonomic disorders may develop or worsen following a COVID-19 infection, whilst the association with COVID-19 vaccines remains controversial. Despite the severe pandemic impact on European clinical autonomic practice, a specialized diagnostic work-up was pivotal to identify non-autonomic disorders in people with post-COVID-19 orthostatic complaints. 相似文献14.
目的 探讨帕金森病(PD)患者体位性低血压(0H)和餐后低血压(PPH)的相关危险因素.方法 对55例原发性PD患者(PD组)和35例健康对照者(正常对照组)进行清醒后、早餐前15 min和早餐后60 min卧位和直立位血压的测量,以及PD自主神经症状量表(SCOPA-AUT)评分,并对结果进行比较.分析OH和PPH的相关危险因素.结果 PD组餐后立位收缩压及舒张压显著低于正常对照组(均P<0.01);OH、PPH发生率及SCOPA-AUT总分和各项评分均显著高于正常对照组(均P<0.01).PD患者OH与左旋多巴等效剂量换算呈正相关(P <0.05);PPH与PD病程及OH呈正相关,与SCOPA-AUT中瞳孔调节分数呈负相关(均P<0.05).结论 PD患者OH和PPH的发生率高.抗PD药物剂量大是PD患者OH发生的危险因素.病程长、OH及瞳孔副交感神经功能损害是发生PPH的危险因素. 相似文献
15.
Gur AY Auriel E Korczyn AD Gadoth A Shopin L Giladi N Bornstein NM Gurevich T 《Acta neurologica Scandinavica》2012,126(1):32-36
Gur AY, Auriel E, Korczyn AD, Gadoth A, Shopin L, Giladi N, Bornstein NM, Gurevich T. Vasomotor reactivity as a predictor for syncope in patients with orthostatism.Acta Neurol Scand: 2012: 126: 32–36.© 2011 John Wiley & Sons A/S. Objectives – Syncope in patients with orthostatic hypotension (OH) may be the result of impaired cerebral autoregulation. Cerebral autoregulation status can be determined by assessing cerebral vasomotor reactivity (VMR). We assessed and compared VMR in patients with OH with and without syncope. Material and methods – Twenty‐nine patients with OH underwent transcranial Doppler (TCD) and the Diamox test (1 g acetazolamide IV) for assessing VMR during elaboration of their OH syndrome. The percent difference between cerebral blood flow velocities (BFV) in the middle cerebral (MCA) and vertebral (VA) arteries before and after acetazolamide was defined as VMR%. We considered increases of BFV of ≥40% as being indicative of good VMR and classified our study patients as having good or impaired VMRs accordingly. Results – Mean VMR% values of the MCA and VA in patients with OH with syncope (n = 12) were significantly lower as compared with patients with OH without syncope (n = 17): 25.2 ± 20.5% and 42.5 ± 18.6%; 20.9 ± 15.5% and 40.8 ± 28.5%, respectively (P < 0.05). Conclusions – Among patients with OH, we found an association between the presence of syncope and impaired VMR. Assessment of VMR among patients with OH may predict those who are at higher risk to faint and fall and to support more aggressive intervention. 相似文献
16.
Fainting in animals 总被引:2,自引:0,他引:2
Fainting (syncope) is
unconsciousness due to insufficient
cerebral circulation in the context
of a temporary failure of the systemic
circulation. This paper firstly
aims to discuss fainting in animals,
and secondly to discuss animal
physiology to broaden the understanding
of human fainting.Of the three major syncope
types (cardiac, orthostatic and reflex
syncope), only cardiac syncope
occurs in animals as in man,
through arrhythmia or output failure.Mans orthostatic fainting tendency
has been blamed on his upright
posture. A comparison with
animals shows that giraffes, treeclimbing
snakes, and animals that
quickly raise and lower their heads
face more serious gravitational circulatory
challenges than man, but
do not appear to faint. Merely carrying
the brain above the heart
does not explain a fainting tendency,
as the human heart-to-brain
height is smaller than that of many
mammals with similar blood pressure.
Two evolutionary novelties
may be to blame: the proportion of
cardiac output going upwards to
the brain is much larger than in
apes, and mans large legs suggest
that the volume lost to venous
pooling is also larger.Emotional factors play a role in
many reflex syncope events. Tonic
immobility (feigning death,playing
possum) is not a good model,
as it concerns immobility as a survival
strategy of an attentive brain,
rather than unconsciousness due to
circulatory breakdown. Whether
orienting and defense responses
form a valid model remains to be
proven. Emotional fainting may be
uniquely human; how mental
processes can shut down the circulation
and thereby the brain needs
serious study, as it may hold the
key to syncope prevention. 相似文献
17.
Lagi A. Vannucchi P. L. Arnetoli G. 《The Italian Journal of Neurological Sciences》1992,13(3):203-207
159 patients with a previous discharge diagnosis of recurrent vasodepressor syncope associated with prolonged standing or other circumstance known to trigger the condition were examined in order to isolate the orthostatic form. 72 patients with a history of at least two episodes of loss of consciousness after standing still for at least 10' were selected for testing by head-up tilt. Those who showed signs or symptoms during the test were tested a further twice, the third time after atropine administration. This process resulted in the diagnosis of orthostatic vasodepressor syncope in 28 patients who presented both 1) a positive test associated with hypotension and bradycardia and 2) bradycardia-free hypotention on repetition of the test with atropine.
Sommario Abbiamo studiato 159 pazienti diagnosticati come affetti da sincope vasodepressiva associata a differenti condizioni ed in particolare anche alla prolungata stazione eretta. Fra questi ne selezionammo 72 che nell'anamnesi presentavano almeno due episodi di perdita di coscienza in ortostatismo. 71 soggetti, paragonabili per sesso ed età, costituirono il gruppo di controllo. I 143 pazienti così individuati furono sottoposti a tilting: quelli positivi lo ripeterono altre due volte, l'ultima con contemporanea somministrazione di atropina.Questo iter diagnostico portò alla diagnosi di sincope ortostatica vasodepressiva in 28 soggetti che presentarono: 1) la positività del test associata a ipotensione e bradicardia, 2) una ipotensione senza bradicardia durante la ripetizione del test con atropina.Infine fu possibile identificare due piccoli sottogruppi di pazienti che manifestarono durante il test asistolia (2 pazienti) e ipotensione associata a tachicardia (sincope simpatotonica, 3 casi) per i quali sono indicati provvedimenti terapeutici differenziati.相似文献
18.
Dr. Chie-Wei Fan MB MRCPI Declan Gasparro BSc MSc Vivion Crowley MRCPath FFPath Conal J. Cunningham MD FRCPI 《Clinical autonomic research》2009,19(1):51-57
Objective Our aim was to investigate the effect of monotherapy of sleeping head-up (SHU) at 6 in. in a group of older inpatients with
OH from all causes.
Methods We recruited nine consecutive inpatients (mean age (SD) 76(5) years) with persistent, symptomatic OH with a mean systolic
blood pressure (SBP) drop on standing and nadir SBP of 68 (27.8) and 94 (19.2) mmHg respectively. All patients underwent SHU
for 1 week. Beat-to-beat haemodynamics during lying and standing, 24-hour ambulatory blood pressure, supine haematocrit, urea/electrolytes,
plasma renin activity and aldosterone were measured before and after intervention.
Results One week after SHU, SBP, stroke volume and cardiac output increased significantly (all P < 0.05) by 12 mmHg, 15 ml and 1.3 l/minutes respectively while heart rate and total peripheral resistance were significantly
reduced by 3.6 bpm and 0.355 dynes/s/cm5 respectively during 2 minute of standing. Serum creatinine was also significantly lower. Five patients improved in their
mobility following SHU.
Interpretations SHU for 1 week at 6 in. was well tolerated by older in-patients with OH, associated with improved orthostatic tolerance, and
with haemodynamic changes in keeping with increased extracellular volume. SHU at 6 in. has a role in the acute treatment of
OH for patients in hospital, but its longer-term effects and in the out-patient setting require further study.
Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.
Clinical trial registration information: Not a clinical trial. 相似文献
19.
Victoria Elizabeth Claydon PhD Nabeela Raheena Younis BSc Roger Hainsworth MB PhD DSc 《Clinical autonomic research》2006,16(2):98-104
Abstract Women of child-bearing age have a lower orthostatic tolerance (OT) than older women or men, and women suffering from frequent
syncopal episodes often comment that their symptoms occur at certain times of the menstrual cycle. However, it is not known
whether, in asymptomatic women, OT varies at different phases of the menstrual cycle. We studied 8 healthy asymptomatic women
aged 26.8±3.4 years. We determined OT using a test of combined head-up tilting and lower body suction. We continuously monitored
beat-to-beat blood pressure (Finapres), heart rate (ECG), and cerebral and forearm blood flow velocities (Doppler ultrasound).
On each test day we assessed carotid baroreceptor sensitivity from suction/pressure applied to a neck chamber. We also determined
estradiol and progesterone levels from a venous blood sample. Tests were performed in early follicular and late luteal phases,
and during ovulation. Serum concentrations of estradiol (pmol • l–1) and progesterone (nmol • l–1) were in follicular phase 464.1 ± 63 and 6.3 ± 2.8; ovulation 941.6 ± 298 and 5.8 ± 1.2; luteal phase 698±188 and 32.3 ±
9.6. Progesterone levels were significantly higher in the luteal phase (p < 0.001). OT was not different on any test day:
follicular 31.9 ± 1.6 min, ovulation 31.3 ± 0.7 min; luteal 31.1 ± 2.2 min. Supine and tilted heart rates and blood pressures,
the maximum heart rate, and the cerebral autoregulatory and forearm vascular resistance responses to the orthostatic stress
were similar during all studies. Both cardiac and vascular resistance carotid baroreceptor sensitivities were also similar
on all test days. These results suggest that there is no difference in either OT or cardiovascular control at the tested phases
of the menstrual cycle in healthy women. 相似文献
20.
Jacques-Olivier Fortrat Daniel Schang Elisabeth Bellard Jacques Victor Georges Lefthériotis 《Clinical autonomic research》2007,17(4):206-210
Reflex syncope is a well-recognized phenomenon, but the understanding of its underlying pathophysiology remains limited. We
hypothesized that patients with a history of syncope and a positive head-up tilt test (HUTT) outcome are in a “not-yet defined”
abnormal state even before the head-up position. We performed a 45 min HUTT on 86 patients with a history of syncope. We assessed
19 variables during the supine period before head-up position. Of these variables, 9 were cardiovascular variables (CV) while
8 were body composition variables (BC). The two remaining variables were age and sex. Forty-five patients (41 ± 15 years,
22 males) have a positive HUTT outcome and 41 a negative one (46 ± 15 years, 22 males). Statistical tests applied on each
of the 19 variables individually did not discriminate patients with a positive and a negative outcome. We used neural networks
to screen the sets of variables that allowed for the best predictions of HUTT outcomes. The sensitivity, specificity, positive
and negative predictive values (PPV and NPV, respectively) were determined. The best set of predictive values determined from
the 19 variables was 76, 81, 78 and 80% for sensitivity, sensibility, PPV, and NPV, respectively. Unexpectedly, the HUTT outcome
prediction performed with cardiovascular variables was not better than the prediction performed with body composition variables
only. Patients with a positive HUTT outcome are in an abnormal state that can be detected even before the head-up position.
Body composition is an important contributor to this abnormal state. 相似文献