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Guo Y, Lin T, Lin N, Lin H. Effectiveness analysis of deceleration capacity and traditional heart rate variability in diagnosing vasovagal syncope. Front Cardiovasc Med 2024; 11:1333684. [PMID: 39290211 PMCID: PMC11405235 DOI: 10.3389/fcvm.2024.1333684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Accepted: 08/13/2024] [Indexed: 09/19/2024] Open
Abstract
Background Vasovagal syncope (VVS) is a prevalent medical condition with a lack of efficient methods for its detection. Aim This study aimed to explore an objective clinical indicator in diagnosing VVS. Methods The retrospective analysis involved clinical data of 243 syncope patients from 1 June 2020 to 31 July 2023. Among them, 108 patients had a negative result in the tilt test (TTT), while the remaining 135 patients had a positive result in the TTT. Relevant statistical methods were utilized to examine the correlation between VVS and different indicators of heart rate variability. Results After screening, 354 patients being considered for VVS were evaluated, resulting in a final sample size of 243. Sex, age, deceleration capacity (DC), and standard deviation of all normal-to-normal intervals (SDNNs) were the variables that showed statistical significance between the TTT(-) group and the TTT(+) group. Independent risk factors identified by multivariate logistic regression were DC [odds ratio (OR) 1.710, 95% confidence interval (CI) 1.388-2.106, P < 0.001] and SDNN (OR 1.033, 95% CI 1.018-1.049, P < 0.001). Comparing the groups, receiver operating characteristic analysis revealed a notable distinction in both DC and SDNN [the respective areas under the curve were 0.789 (95% CI 0.730-0.848) and 0.702 (95% CI 0.637-0.767); the cutoff values were 7.15 and 131.42; P < 0.001, respectively]. Conclusion In summary, DC can function as an impartial and easily accessible clinical marker for differentiating VVS. A value exceeding 7.15 ms might suggest a higher likelihood of syncope.
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Affiliation(s)
- Yongzhe Guo
- Department of Cardiology, Fujian Heart Medical Center, Fujian Institute of Coronary Heart Disease, Fujian Medical University Union Hospital, Fuzhou, China
| | - Tao Lin
- Department of Epidemiology, School of Public Health, Fujian Medical University, Fuzhou, China
| | - Nanyu Lin
- Department of Cardiology, Fujian Heart Medical Center, Fujian Institute of Coronary Heart Disease, Fujian Medical University Union Hospital, Fuzhou, China
| | - Huizhong Lin
- Department of Cardiology, Fujian Heart Medical Center, Fujian Institute of Coronary Heart Disease, Fujian Medical University Union Hospital, Fuzhou, China
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Rodriguez S, Haimovich S, Vitale SG, Alonso L, Carugno J. Vasovagal Syncope during Office Hysteroscopy—A Frequently Overlooked Unpleasant Complication. Medicina (B Aires) 2022; 58:medicina58111626. [PMID: 36422165 PMCID: PMC9693602 DOI: 10.3390/medicina58111626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 11/10/2022] [Accepted: 11/10/2022] [Indexed: 11/16/2022] Open
Abstract
Due to technological advancements in miniaturization of instruments and improved optics, the number of office hysteroscopic procedures has increased over time. Office hysteroscopy is preferred due to avoidance of general anesthesia and decreased overall cost. Vasovagal syncope has been implied as the most common complication. Vasovagal syncope is associated with inappropriate reflex vasodilation and bradycardia in the setting of an acute malfunction between the autonomic nervous system and the cardiovascular system; however, there is no mortality associated with vasovagal syncope. A management strategy for acute vasovagal reflex during office hysteroscopy is proposed in order to manage this common complication.
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Affiliation(s)
- Suset Rodriguez
- Minimally Invasive Gynecology Unit, Obstetrics, Gynecology and Reproductive Sciences Department, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
- Correspondence:
| | - Sergio Haimovich
- Hillel Yaffe Medical Center, Technion-Israel Technology Institute, Hadera 32000, Israel
| | - Salvatore Giovanni Vitale
- Obstetrics and Gynecology Unit, Department of General Surgery and Medical Surgical Specialties, University of Catania, 95121 Catania, Italy
| | - Luis Alonso
- Centro Gutenberg, Endoscopy Unit, 29012 Malaga, Spain
| | - Jose Carugno
- Minimally Invasive Gynecology Unit, Obstetrics, Gynecology and Reproductive Sciences Department, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
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Miranda CM, da Silva RMFL, Peruhybe-Magalhães V, Brugada J. Vasoactive Biomarkers in Patients With Vasovagal Syncope During Head-Up Tilt Test: A Case-Control Study. CLINICAL MEDICINE INSIGHTS-CARDIOLOGY 2022; 16:11795468221116848. [PMID: 36046183 PMCID: PMC9421056 DOI: 10.1177/11795468221116848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 06/15/2022] [Indexed: 11/25/2022]
Abstract
Background: Vasovagal syncope (VVS) is the most common cause of syncope. Some stages of its pathophysiological mechanisms remain unclear. Vasoactive substances such as nitric oxide metabolites (NOx) and endothelin (ET) may be involved during acute orthostatic stress. Objective: To analyze plasma changes in NOx and ET and heart rate variability (HRV) in the supine positions (T1) and during the head-up tilt test (HUTT) (T2), in patients with VVS (case group) and control group. Methods: Thirty-seven patients (17 in the case group and 20 in the control group), matched for age and sex (mean aged 31.8 years) underwent HUTT with simultaneous HRV recording and venipuncture. Blood samples were collected during phases T1 and T2 and the analysis was performed without knowledge of the HUTT result. Results: In the total sample, there was an increase in NOx values (P = .014), however there was no increase in ET values from phase T1 to phase T2. Patients with VVS tended to increase plasma NOx values (P = .057) and had significantly higher plasma values compared to ET (P = .033) between phases T1 to T2. In the control group, there was no significant change in the values of these vasoactive substances. Regarding HRV, there were a decrease in the component HF (high frequency) and increased of the LF (low frequency)/HF ratio during HUTT. Conclusions: There was an increase in ET during HUTT occurred only in the case group. These patients are more likely to have an imbalance between antagonistic vasoactive biomarkers during orthostatic stress.
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Affiliation(s)
- Cláudia Madeira Miranda
- Faculty of Medicine, Federal University of Minas Gerais, Brazil.,Madre Teresa Hospital, Minas Gerais, Brazil
| | | | | | - Josep Brugada
- Institut Clínic Cardiovascular, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain
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Gelpi F, Bari V, Cairo B, De Maria B, Tonon D, Rossato G, Faes L, Porta A. Dynamic cerebrovascular autoregulation in patients prone to postural syncope: Comparison of techniques assessing the autoregulation index from spontaneous variability series. Auton Neurosci 2021; 237:102920. [PMID: 34808528 DOI: 10.1016/j.autneu.2021.102920] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 10/20/2021] [Accepted: 11/15/2021] [Indexed: 10/19/2022]
Abstract
Three approaches to the assessment of cerebrovascular autoregulation (CA) via the computation of the autoregulation index (ARI) from spontaneous variability of mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) were applied: 1) a time domain method (TDM); 2) a nonparametric method (nonPM); 3) a parametric method (PM). Performances were tested over matched and surrogate unmatched pairs. Data were analyzed at supine resting (REST) and during the early phase of 60° head-up tilt (TILT) in 13 subjects with previous history of postural syncope (SYNC, age: 28 ± 9 yrs.; 5 males) and 13 control individuals (noSYNC, age: 27 ± 8 yrs.; 5 males). Analysis was completed by computing autonomic markers from heart period (HP) and systolic arterial pressure (SAP) variability series via spectral approach. HP and SAP spectral indexes suggested that noSYNC and SYNC groups exhibited different autonomic responses to TILT. ARI analysis indicated that: i) all methods have a sufficient statistical power to separate matched from unmatched pairs with the exception of nonPM applied to impulse response; ii) ARI estimates derived from different methods might be uncorrelated and, even when correlated, might exhibit a significant bias; iii) orthostatic stressor did not induce any evident ARI change in either noSYNC or SYNC individuals; iv) this conclusion held regardless of the method. Methods for the ARI estimation from spontaneous variability provide different ARIs but none indicate that noSYNC and SYNC subjects have different dynamic component of CA.
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Affiliation(s)
- Francesca Gelpi
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | - Vlasta Bari
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy
| | - Beatrice Cairo
- Department of Biomedical Sciences for Health, University of Milan, Milan, Italy
| | | | - Davide Tonon
- Department of Neurology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar, Verona, Italy
| | - Gianluca Rossato
- Department of Neurology, IRCCS Sacro Cuore Don Calabria Hospital, Negrar, Verona, Italy
| | - Luca Faes
- Department of Engineering, University of Palermo, Palermo, Italy
| | - Alberto Porta
- Department of Cardiothoracic, Vascular Anesthesia and Intensive Care, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; Department of Biomedical Sciences for Health, University of Milan, Milan, Italy.
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Myrovali E, Fragakis N, Vassilikos V, Hadjileontiadis LJ. Efficient syncope prediction from resting state clinical data using wavelet bispectrum and multilayer perceptron neural network. Med Biol Eng Comput 2021; 59:1311-1324. [PMID: 33959855 DOI: 10.1007/s11517-021-02353-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 03/19/2021] [Indexed: 11/28/2022]
Abstract
Neurally mediated syncope (NMS) is the most common type of syncope, and head up tilt test (HUTT) is, so far, the most appropriate tool to identify NMS. In this work, an effort to predict the NMS before performing the HUTT is attempted. To achieve this, the heart rate variability (HRV) at rest and during the first minutes of tilting position during HUTT was analyzed using both time and frequency domains. Various features from HRV regularity and complexity, along with wavelet higher-order spectrum (WHOS) analysis in low-frequency (LF) and high-frequency (HF) bands were examined. The experimental results from 26 patients with history of NMS have shown that at rest, a time domain entropy measure and WHOS-based features in LF band exhibit significant differences between positive and negative HUTT as well as among 10 healthy subjects and NMS patients. The best performance of multilayer perceptron neural network (MPNN) was achieved by using an input vector consisted of WHOS-based HRV features in the LF zone and systolic blood pressure from the resting period, yielding an accuracy of 89.7%, assessed by 5-fold cross-validation. The promising results presented here pave the way for an early prediction of the HUTT outcome from resting state, contributing to the identification of patients at higher risk NMS. The HRV analysis along with systolic blood pressure at rest predict NMS using a multilayer perceptron neural network.
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Affiliation(s)
- Evangelia Myrovali
- Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, GR 54645, Thessaloniki, Greece.
| | - Nikolaos Fragakis
- 3rd Cardiology Department, Aristotle University of Thessaloniki, Hippokration General Hospital, 49 Konstantinoupoleos str, 54642, Thessaloniki, Greece
| | - Vassilios Vassilikos
- 3rd Cardiology Department, Aristotle University of Thessaloniki, Hippokration General Hospital, 49 Konstantinoupoleos str, 54642, Thessaloniki, Greece
| | - Leontios J Hadjileontiadis
- Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, GR 54645, Thessaloniki, Greece.,Department of Electrical and Computer Engineering, Khalifa University of Science and Technology, PO BOX 127788, Abu Dhabi, UAE
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Zheng L, Sun W, Liu S, Liang E, Du Z, Guo J, Wu L, Asirvatham SJ, Yao Y. The Diagnostic Value of Cardiac Deceleration Capacity in Vasovagal Syncope. Circ Arrhythm Electrophysiol 2020; 13:e008659. [PMID: 33197331 DOI: 10.1161/circep.120.008659] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Increased parasympathetic activity is thought to play important roles in syncope events of patients with vasovagal syncope (VVS). However, direct measurements of the vagal control are difficult. The novel deceleration capacity (DC) of heart rate measure has been used to characterize the vagal modulation. This study aimed to assess vagal control in patients with VVS and evaluate the diagnostic value of the DC in VVS. METHODS Altogether, 161 consecutive patients with VVS (43±15 years; 62 males) were enrolled. Tilt table test was positive in 101 and negative in 60 patients. Sixty-five healthy subjects were enrolled as controls. DC and heart rate variability in 24-hour ECG, echocardiogram, and biochemical examinations were compared between the syncope and control groups. RESULTS DC was significantly higher in the syncope group than in the control group (9.6±3.3 versus 6.5±2.0 ms, P<0.001). DC was similarly increased in patients with VVS with a positive and negative tilt table test (9.7±3.5 and 9.4±2.9 ms, P=0.614). In multivariable logistic regression analyses, DC was independently associated with syncope (odds ratio=1.518 [95% CI, 1.301-1.770]; P=0.0001). For the prediction of syncope, the area under curve analysis showed similar values when comparing single DC and combined DC with other risk factors (P=0.1147). From the receiver operator characteristic curves for syncope discrimination, the optimal cutoff value for the DC was 7.12 ms. CONCLUSIONS DC>7.5 ms may serve as a good tool to monitor cardiac vagal activity and discriminate VVS, particularly in those with negative tilt table test.
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Affiliation(s)
- Lihui Zheng
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
| | - Wei Sun
- Department of cardiology, Beijing Tsinghua Changgung Hospital Medical Center, Tsinghua University, China (W.S.)
| | - Shangyu Liu
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
| | - Erpeng Liang
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
| | - Zhongpeng Du
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
| | - Jingrui Guo
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
| | - Lingmin Wu
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
| | - Samuel J Asirvatham
- Division of Cardiovascular Diseases, Mayo Clinic & Mayo Foundation, Rochester, MN (S.J.A.)
| | - Yan Yao
- Arrhythmia Center, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College (L.Z., S.L., E.L., Z.D., J.G., L.W., Y.Y.)
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7
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Wang Y, Zhang C, Chen S, Li X, Jin H, Du J. Frequency Domain Indices of Heart Rate Variability are Useful for Differentiating Vasovagal Syncope and Postural Tachycardia Syndrome in Children. J Pediatr 2019; 207:59-63. [PMID: 30626483 DOI: 10.1016/j.jpeds.2018.11.054] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/27/2018] [Accepted: 11/29/2018] [Indexed: 10/27/2022]
Abstract
OBJECTIVE To explore the value of frequency domain indices of heart rate variability (HRV) in the differential diagnosis between pediatric vasovagal syncope and postural tachycardia syndrome (POTS). STUDY DESIGN Eighty-five patients aged 7-16 years with either vasovagal syncope or POTS were enrolled in the experimental group; 18 healthy children served as controls. Holter electrocardiography was used to detect HRV frequency-domain indices in patients with vasovagal syncope, patients with POTS, and control subjects. The differences in HRV indices were compared between the vasovagal syncope and POTS groups. The receiver operating characteristic (ROC) curve was calculated to analyze the predictive value of HRV for the differential diagnosis between vasovagal syncope and POTS in children. In addition, 37 children aged 7-17 years with either vasovagal syncope or POTS were recruited as an external validation group. RESULTS The daytime ultra-low frequency (dULF), nighttime ULF (nULF), daytime very low frequency (dVLF), and nighttime VLF (nVLF) were higher in the vasovagal syncope group compared with the POTS group (P < .01 for dULF, dVLF, and nVLF; P < .05 for nULF). The dULF, nULF, dVLF, and nVLF yielded a sensitivity of 73.3%, 71.1%, 68.9%, and 62.2%, respectively, and a specificity of 72.5%, 62.5%, 60.0%, and 60.0%, respectively, to differentiate vasovagal syncope from POTS. The external validation with clinical diagnostic standard showed that a dULF cutoff value of 36.2 ms2 for differentiating POTS from vasovagal syncope yielded a sensitivity of 71.4%, a specificity of 75.0%, and an accuracy of 73.0%. CONCLUSION dULF may be a useful measure for the differential diagnosis between vasovagal syncope and POTS in adolescents.
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Affiliation(s)
- Yuanyuan Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Chunyu Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Selena Chen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA
| | - Xueying Li
- Department of Medical Statistics, Peking University First Hospital, Beijing, China
| | - Hongfang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Junbao Du
- Department of Pediatrics, Peking University First Hospital, Beijing, China; Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing, China.
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Medow MS, Kothari ML, Goetz AM, O'Donnell-Smith MB, Terilli C, Stewart JM. Decreasing cerebral oxygen consumption during upright tilt in vasovagal syncope. Physiol Rep 2018; 5:e13286. [PMID: 28554964 PMCID: PMC5449565 DOI: 10.14814/phy2.13286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 04/25/2017] [Accepted: 04/26/2017] [Indexed: 11/24/2022] Open
Abstract
We measured changes in transcranial Doppler ultrasound (TCD) and near infrared spectroscopy (NIRS) during 70° upright tilt in patients with recurrent vasovagal syncope (VVS, N = 20), postural tachycardia syndrome (POTS, N = 20), and healthy controls (N = 12) aged 15–27 years old. VVS was included if they fainted during testing within 5–15 min of upright tilt. We combined TCD and NIRS to obtain estimates of percent change in the cerebral metabolic rate of oxygen consumption (CMRO2), cerebral blood flow velocity (CBFv), and oxygen extraction fraction (OEF). Over the course of 10 min of upright tilt, CBFv decreased from a baseline of 70 ± 5 to 63 ± 5 cm/sec in controls and 74 ± 3 to 64 ± 3 cm/sec in POTS while decreasing from 74 ± 4 to 44 ± 3 cm/sec in VVS. CMRO2 was unchanged in POTS and controls during tilt while OEF increased by 19 ± 3% and 15 ± 3%, respectively. CMRO2 decreased by 31 ± 3% in VVS during tilt while OEF only increased by 7 ± 3%. Oxyhemoglobin decreased by 1.1 ± 1.3 μmol/kg brain tissue in controls, by 1.1 ± 1.3 μmol/kg in POTS, and 11.1 ± 1.3 μmol/kg in VVS. CBFv and CMRO2 fell steadily in VVS during upright tilt. The deficit in CMRO2 in VVS results from inadequate OEF in the face of greatly reduced CBF.
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Affiliation(s)
- Marvin S Medow
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Mira L Kothari
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Amanda M Goetz
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Mary Breige O'Donnell-Smith
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Courtney Terilli
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Julian M Stewart
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
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Arnold AC, Ng J, Lei L, Raj SR. Autonomic Dysfunction in Cardiology: Pathophysiology, Investigation, and Management. Can J Cardiol 2017; 33:1524-1534. [PMID: 29102451 PMCID: PMC5705288 DOI: 10.1016/j.cjca.2017.09.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/19/2017] [Accepted: 09/06/2017] [Indexed: 12/24/2022] Open
Abstract
Presyncope and syncope are common medical findings, with a > 40% estimated lifetime prevalence. These conditions are often elicited by postural stress and can be recurrent and accompanied by debilitating symptoms of cerebral hypoperfusion. Therefore, it is critical for physicians to become familiar with the diagnosis and treatment of common underlying causes of presyncope and syncope. In some patients, altered postural hemodynamic responses result from a failure of compensatory autonomic nervous system reflex mechanisms. The most common presentations of presyncope and syncope secondary to this autonomic dysfunction include vasovagal syncope, neurogenic orthostatic hypotension, and postural tachycardia syndrome. The most sensitive method for diagnosis is a detailed initial evaluation with medical history, physical examination, and resting electrocardiogram to rule out cardiac syncope. Physical examination should include measurement of supine and standing blood pressure and heart rate to identify the pattern of hemodynamic regulation during orthostatic stress. Additional testing may be required in patients without a clear diagnosis after the initial evaluation. Management of patients should focus on improving symptoms and functional status and not targeting arbitrary hemodynamic values. An individualized structured and stepwise approach should be taken for treatment, starting with patient education, lifestyle modifications, and use of physical counter-pressure manoeuvres and devices to improve venous return. Pharmacologic interventions should be added only when conservative approaches are insufficient to improve symptoms. There are no gold standard approaches for pharmacologic treatment in these conditions, with medications often used off label and with limited long-term data for effectiveness.
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Affiliation(s)
- Amy C Arnold
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania, USA; Autonomic Dysfunction Center, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jessica Ng
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Lucy Lei
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada; Autonomic Dysfunction Center, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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Ciliberti MAP, Santoro F, Di Martino LFM, Rinaldi AC, Salvemini G, Cipriani F, Triggiani AI, Moscatelli F, Valenzano A, Di Biase M, Brunetti ND, Cibelli G. Predictive value of very low frequency at spectral analysis among patients with unexplained syncope assessed by head-up tilt testing. Arch Cardiovasc Dis 2017; 111:95-100. [PMID: 28958870 DOI: 10.1016/j.acvd.2017.04.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 04/19/2017] [Indexed: 11/30/2022]
Abstract
BACKGROUND The role of heart rate variability (HRV) in the prediction of vasovagal syncope during head-up tilt testing (HUTt) is unclear. AIM To evaluate the ability of the spectral components of HRV at rest to predict vasovagal syncope among patients with unexplained syncope referred for HUTt. METHODS Twenty-six consecutive patients with unexplained syncope were enrolled in the study. All patients underwent HRV evaluation at rest (very low frequency [VLF], low frequency [LF], high frequency [HF] and LF/HF ratio) and during HUTt. HUTt was performed using the Westminster protocol. Continuous electrocardiogram and blood pressure monitoring were performed throughout the test. RESULTS Eight (31%) patients developed syncope during HUTt. There were no baseline differences in terms of clinical features and HRV variables among patients who developed syncope and those who did not, except for VLF (2421 vs 896ms2; P<0.001). In the multivariable logistic regression analysis, including age and sex, VLF was the only independent variable associated with syncope during HUTt (odds ratio 1.002, 95% confidence interval 1.0003-1.0032; P=0.02). The area under the curve at rest was 0.889 for VLF, 0.674 for HF and 0.611 for LF. A value of VLF>2048ms2 was the optimal cut-off to predict syncope during HUTt (sensitivity 87.5%, specificity 72.2%). CONCLUSIONS VLF at rest predicted the incidence of syncope during HUTt. Further studies are warranted to confirm these preliminary data.
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Affiliation(s)
| | - Francesco Santoro
- Department of Medical & Surgical Sciences, University of Foggia, viale Pinto 1, 71122 Foggia, Italy
| | | | - Antonio Cosimo Rinaldi
- Department of Medical & Surgical Sciences, University of Foggia, viale Pinto 1, 71122 Foggia, Italy
| | - Giuseppe Salvemini
- Department of Medical & Surgical Sciences, University of Foggia, viale Pinto 1, 71122 Foggia, Italy
| | - Francesco Cipriani
- Department of Medical & Surgical Sciences, University of Foggia, viale Pinto 1, 71122 Foggia, Italy
| | | | - Fiorenzo Moscatelli
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; Department of Motor, Human and Health Sciences, University of Rome "Foro Italico", 00197 Rome, Italy
| | - Anna Valenzano
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy
| | - Matteo Di Biase
- Department of Medical & Surgical Sciences, University of Foggia, viale Pinto 1, 71122 Foggia, Italy
| | - Natale Daniele Brunetti
- Department of Medical & Surgical Sciences, University of Foggia, viale Pinto 1, 71122 Foggia, Italy.
| | - Giuseppe Cibelli
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy
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Stewart JM, Suggs M, Merchant S, Sutton R, Terilli C, Visintainer P, Medow MS. Postsynaptic α1-Adrenergic Vasoconstriction Is Impaired in Young Patients With Vasovagal Syncope and Is Corrected by Nitric Oxide Synthase Inhibition. Circ Arrhythm Electrophysiol 2017; 9:CIRCEP.115.003828. [PMID: 27444639 DOI: 10.1161/circep.115.003828] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 06/15/2016] [Indexed: 11/16/2022]
Abstract
BACKGROUND Syncope is a sudden transient loss of consciousness and postural tone with spontaneous recovery; the most common form is vasovagal syncope (VVS). During VVS, gravitational pooling excessively reduces central blood volume and cardiac output. In VVS, as in hemorrhage, impaired adrenergic vasoconstriction and venoconstriction result in hypotension. We hypothesized that impaired adrenergic responsiveness because of excess nitric oxide can be reversed by reducing nitric oxide. METHODS AND RESULTS We recorded cardiopulmonary dynamics in supine syncope patients and healthy volunteers (aged 15-27 years) challenged with a dose-response using the α1-agonist phenylephrine (PE), with and without the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, monoacetate salt (L-NMMA). Systolic and diastolic pressures among control and VVS were the same, although they increased after L-NMMA and saline+PE (volume and pressor control for L-NMMA). Heart rate was significantly reduced by L-NMMA (P<0.05) for control and VVS compared with baseline, but there was no significant difference in heart rate between L-NMMA and saline+PE. Cardiac output and splanchnic blood flow were reduced by L-NMMA for control and VVS (P<0.05) compared with baseline, while total peripheral resistance increased (P<0.05). PE dose-response for splanchnic flow and resistance were blunted for VVS compared with control after saline+PE, but enhanced after L-NMMA (P<0.001). Postsynaptic α1-adrenergic vasoconstrictive impairment was greatest in the splanchnic vasculature, and splanchnic blood flow was unaffected by PE. Forearm and calf α1-adrenergic vasoconstriction were unimpaired in VVS and unaffected by L-NMMA. CONCLUSIONS Impaired postsynaptic α1-adrenergic vasoconstriction in young adults with VVS can be corrected by nitric oxide synthase inhibition, demonstrated with our use of L-NMMA.
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Affiliation(s)
- Julian M Stewart
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.).
| | - Melissa Suggs
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Sana Merchant
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Richard Sutton
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Courtney Terilli
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Paul Visintainer
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.)
| | - Marvin S Medow
- From the Departments of Pediatrics (J.M.S., S.M., C.T., M.S.M.), Physiology (J.M.S., M.S., M.S.M.), New York Medical College, Valhalla, NY; The National Heart & Lung Institute, Imperial College, London, United Kingdom (R.S.); and Department of Medicine, Baystate Medical Center, Springfield & Tufts University School of Medicine, MA (P.V.).
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Deceleration capacity-a novel measure for autonomic nervous system in patients with vasovagal syncope on tilt-table testing. ACTA ACUST UNITED AC 2017; 37:326-331. [PMID: 28585146 DOI: 10.1007/s11596-017-1735-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Revised: 07/25/2016] [Indexed: 10/18/2022]
Abstract
This study was to investigate the changes of autonomic nerve function and hemodynamics in patients with vasovagal syncope (VVS) during head-up tilt-table testing (HUT). HUT was performed in 68 patients with unexplained syncope and 18 healthy subjects served as control group. According to whether bradycardia, hypotension or both took place during the onset of syncope, the patients were divided during the test into three subgroups: vasodepressor syncope (VD), cardioinhibitory syncope (CI) and mixed syncope (MX) subgroups. Heart rate, blood pressure, heart rate variability (HRV), and deceleration capacity (DC) were continuously analyzed during HUT. For all the subjects with positive responses, the normalized low frequency (LFn) and the LF/HF ratio markedly decreased whereas normalized high frequency (HFn) increased when syncope occurred. Syncopal period also caused more significant increase in the power of the DC in positive groups. These changes were more exaggerated compared to controls. All the patients were indicative of a sympathetic surge in the presence of withdrawal vagal activity before syncope and a sympathetic inhibition with a vagal predominance at the syncopal stage by the frequency-domain analysis of HRV. With the measurements of DC, a decreased vagal tone before syncope stage and a vagal activation at the syncopal stage were observed. The vagal tone was higher in subjects showing cardioinhibitory responses at the syncopal stage. DC may provide an alternative method to understand the autonomic profile of VVS patients.
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Miranda CM, da Silva RMFL. Analysis of Heart Rate Variability Before and During Tilt Test in Patients with Cardioinhibitory Vasovagal Syncope. Arq Bras Cardiol 2016; 107:568-575. [PMID: 28558089 PMCID: PMC5210461 DOI: 10.5935/abc.20160177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 07/14/2016] [Accepted: 08/08/2016] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Cardioinhibitory vasovagal response is uncommon during the tilt test (TT). Heart rate variability (HRV) by use of spectral analysis can distinguish patients with that response. OBJECTIVE To compare the HRV in patients with cardioinhibitory vasovagal syncope (case group - G1) with that in patients without syncope and with negative response to TT (control group - G2). METHODS 64 patients were evaluated (mean age, 36.2 years; 35 men) and submitted to TT at 70 degrees, under digital Holter monitoring. The groups were paired for age and sex (G1, 40 patients; G2, 24). RESULTS In G1, 21 patients had a type 2A response and 19 had type 2B, with mean TT duration of 20.4 minutes. There was a greater low frequency (LF) component (11,6 versus 4,5 ms2, p=0.001) and a lower low/high frequency ratio in the supine position (3,9 versus 4,5 ms2, p=0.008) in G1, with no difference during TT between the groups. Applying the receiver operating characteristic curve for cardioinhibitory response, the area under the curve was 0.74 for the LF component in the supine position (p = 0.001). The following were observed for the cutoff point of 0.35 ms(2) for the LF component: sensitivity, 97.4%; specificity, 83.3%; positive predictive value, 85.3%; negative predictive value, 96.9%; and positive likelihood ratio, 5.8. CONCLUSION HRV in the supine position allowed identifying patients with syncope and cardioinhibitory response with a high negative predictive value and likelihood ratio of 5.8.
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Entropy Measures in the Assessment of Heart Rate Variability in Patients with Cardiodepressive Vasovagal Syncope. ENTROPY 2015. [DOI: 10.3390/e17031007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Karbasi-Afshar R, Saburi A, Shahmari A, Khosravi A. Sub-Lingual Spray Versus Pearl of TNG as A Provocative Agent for Tilt Table Test. J Clin Diagn Res 2013; 7:2250-2. [PMID: 24298489 DOI: 10.7860/jcdr/2013/5494.3483] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 08/12/2013] [Indexed: 12/22/2022]
Abstract
OBJECTIVE The aim of this study was to determine the false positive ratio of Tilt Table Test (TTT) result by using TNG spray (Sub-lingual; SL) as compared to TNG pearl in patients referred to military service. MATERIAL AND METHODS This was a prospective study. It was conducted on 110 cases referred for military service, expressed vasovagal symptoms. We divided the subjects into three groups; first Group (60 cases) used TNG pearl for provoking syncope in TTT, Group 2 (50 cases) and Group 3 (control cases) used TNG spray in the same dose (0.4 mg). RESULTS In the first step of tilt study, 10%, and 8% of subjects had fainted on not using provoking drug in cases and controls, respectively. After using the drugs, 36.6%, 96% and 18% showed positive results in pearl, spray and the control groups, respectively (p<0.05). CONCLUSION Rather than pearl group, a 40 minute tilt using TNG spray showed significant higher positive results, which may be incorrectly positive. Using this form of TNG seems not useful for distinguishing and diagnosing vasovagal shocks, especially in subjects referred for military service capacity. For constant evidence, a cross-over clinical trial study is required, involving suspected cases divided into two groups, who both will be examined with spray and pearl.
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Affiliation(s)
- Reza Karbasi-Afshar
- Faculty of Medicine & Cardiovascular Research Center, Department of Cardiovascular Diseases, Baqiyatallah University of Medical Sciences , Tehran, Iran
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Johansen JB, Nielsen JC. Vasovagal syncope: poorly understood, but well handled. Europace 2012; 14:1228-9. [DOI: 10.1093/europace/eus097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Plasma hydrogen sulfide in differential diagnosis between vasovagal syncope and postural orthostatic tachycardia syndrome in children. J Pediatr 2012; 160:227-31. [PMID: 21920536 DOI: 10.1016/j.jpeds.2011.08.008] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2011] [Revised: 06/22/2011] [Accepted: 08/01/2011] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To explore the predictive value of plasma hydrogen sulfide (H(2)S) in differentiating between vasovagal syncope (VVS) and postural orthostatic tachycardia syndrome (POTS) in children. STUDY DESIGN Patients were divided between the POTS group (n=60) and VVS group (n=17) by using either the head-up test or head-up tilt test. Twenty-eight healthy children were selected for the control group. Plasma concentrations of H(2)S were determined for children in all groups (POTS, VVS, and control). RESULTS Plasma levels of H(2)S were significantly higher in children with VVS (95.3±3.8 μmol/L) and POTS (100.9±2.1 μmol/L) than in children in the control group (82.6±6.5 μmol/L). Compared with the VVS group, the POTS group had plasma levels of H(2)S that were significantly increased. The receiver operating characteristic curve for the predictive value of H(2)S differentiation of VVS from POTS showed a H(2)S plasma level of 98 μmol/L as the cutoff value for high probability of distinction. Such a level produced both high sensitivity (90%) and specificity (80%) rates of correctly discriminating between patients with VVS and patients with POTS. CONCLUSION H(2)S plasma level has both high sensitivity and specificity rates to predict the probability of correctly differentiating between patients with VVS and patients with POTS.
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Postural tachycardia syndrome and reflex syncope: similarities and differences. J Pediatr 2009; 154:481-5. [PMID: 19324216 PMCID: PMC3810291 DOI: 10.1016/j.jpeds.2009.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 12/02/2008] [Accepted: 01/06/2009] [Indexed: 11/24/2022]
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Folino AF, Russo G, Porta A, Buja G, Cerutti S, Iliceto S. Autonomic modulation and cardiac contractility in vasovagal syncope. Int J Cardiol 2008; 139:248-53. [PMID: 19049848 DOI: 10.1016/j.ijcard.2008.10.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/06/2008] [Revised: 08/12/2008] [Accepted: 10/12/2008] [Indexed: 11/17/2022]
Abstract
BACKGROUND Previous studies proposed as one of the main mechanisms involved in neurally mediated syncope, the stimulation of ventricular mechanoreceptors as the final trigger for vagal discharge. OBJECTIVES This study aimed to verify the presence of a sympathetic driven increase of cardiac contractility before vasovagal syncope. METHODS We studied 23 patients with recurrent syncope. All underwent a 60 ° tilt with pharmacologic challenge (sublingual spray nitrate). Two conditions were used to assess autonomic activity by heart rate variability analysis: in a supine position after 5 min of rest and after 15 min of tilt. Simultaneously, cardiac contractility was quantified by tissue-Doppler echocardiography at the base of the free walls of left ventricle. The peak myocardial velocities during systole (Sw) and late diastole (Aw) were considered. RESULTS Passive tilt induced a significant increase of the low frequency component (LF) as well as a decrease of the high frequency component (HF) in positive patients (LF: from 49 ± 18 to 65 ± 18 nu, p<0.05; HF: from 41 ± 21 to 26 ± 16 nu, p<0.05). Tissue-Doppler showed a similar increase in Sw in both positive and negative patients but showed a significant decrease of Aw in syncopal subjects (p<0.005). CONCLUSIONS Our results do not show an increase in ventricular contractility before tilt-induced syncope, or in presence of a valuable increase of sympathetic activity. Instead, we observe a reduction of atrial contractility, which may be a contributory component in the pathogenesis of vasovagal syncope.
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MITRO PETER, MUDRÁKOVÁ KLAUDIA, MIČKOVÁ HELENA, DUDÁŠ JÁN, KIRSCH PETER, VALOČIK GABRIEL. Hemodynamic Parameters and Heart Rate Variability during a Tilt Test in Relation to Gene Polymorphism of Renin-Angiotensin and Serotonin System. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2008; 31:1571-80. [DOI: 10.1111/j.1540-8159.2008.01228.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Nowak JA, Ocon A, Taneja I, Medow MS, Stewart JM. Multiresolution wavelet analysis of time-dependent physiological responses in syncopal youths. Am J Physiol Heart Circ Physiol 2008; 296:H171-9. [PMID: 18996985 DOI: 10.1152/ajpheart.00963.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our prior studies indicated that postural fainting relates to thoracic hypovolemia. A supranormal increase in initial vascular resistance was sustained by increased peripheral resistance until late during head-up tilt (HUT), whereas splanchnic resistance, cardiac output, and blood pressure (BP) decreased throughout HUT. Our aim in the present study was to investigate the alterations of baroreflex activity that occur in synchrony with the beat-to-beat time-dependent changes in heart rate (HR), BP, and total peripheral resistance (TPR). We proposed that changes of low-frequency Mayer waves reflect sympathetic baroreflex. We used DWT multiresolution analyses to measure their time dependence. We studied 22 patients, 13 to 21 yr old, 14 who fainted within 10 min of upright tilt (fainters) and 8 healthy control subjects. Multiresolution analysis was obtained of continuous BP, HR, and respirations as a function of time during 70 degrees upright tilt at different scales corresponding to frequency bands. Wavelet power was concentrated in scales corresponding to 0.125 and 0.25 Hz. A major difference from control subjects was observed in fainters at the 0.125 Hz AP scale, which progressively decreased from early HUT. The alpha index at 0.125 Hz was increased in fainters. RR interval 0.25 Hz power decreased in fainters and controls but was markedly increased in fainters with syncope and thereafter corresponding to increased vagal tone compared with control subjects at those times only. The data imply a rapid reduction in time-dependent sympathetic baroreflex activity in fainters but not control subjects during HUT.
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Affiliation(s)
- Jennifer A Nowak
- Pediatrics, Physiology, and Medicine, The Center for Hypotension, New York Medical College, Hawthorne, New York 10532, USA
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Taneja I, Medow MS, Glover JL, Raghunath NK, Stewart JM. Increased vasoconstriction predisposes to hyperpnea and postural faint. Am J Physiol Heart Circ Physiol 2008; 295:H372-81. [PMID: 18502909 DOI: 10.1152/ajpheart.00101.2008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Our prior studies indicated that postural fainting relates to splanchnic hypervolemia and thoracic hypovolemia during orthostasis. We hypothesized that thoracic hypovolemia causes excessive sympathetic activation, increased respiratory tidal volume, and fainting involving the pulmonary stretch reflex. We studied 18 patients 13-21 yr old, 11 who fainted within 10 min of upright tilt (fainters) and 7 healthy control subjects. We measured continuous blood pressure and heart rate, respiration by inductance plethysmography, end-tidal carbon dioxide (ET(CO(2))) by capnography, and regional blood flows and blood volumes using impedance plethysmography, and we calculated arterial resistance with patients supine and during 70 degrees upright tilt. Splanchnic resistance decreased until faint in fainters (44 +/- 8 to 21 +/- 2 mmHg.l(-1).min(-1)) but increased in control subjects (47 +/- 5 to 53 +/- 4 mmHg.l(-1).min(-1)). Percent change in splanchnic blood volume increased (7.5 +/- 1.0 vs. 3.0 +/- 11.5%, P < 0.05) after the onset of tilt. Upright tilt initially significantly increased thoracic, pelvic, and leg resistance in fainters, which subsequently decreased until faint. In fainters but not control subjects, normalized tidal volume (1 +/- 0.1 to 2.6 +/- 0.2, P < 0.05) and normalized minute ventilation increased throughout tilt (1 +/- 0.2 to 2.1 +/- 0.5, P < 0.05), whereas respiratory rate decreased (19 +/- 1 to 15 +/- 1 breaths/min, P < 0.05). Maximum tidal volume occurred just before fainting. The increase in minute ventilation was inversely proportionate to the decrease in ET(CO(2)). Our data suggest that excessive splanchnic pooling and thoracic hypovolemia result in increased peripheral resistance and hyperpnea in simple postural faint. Hyperpnea and pulmonary stretch may contribute to the sympathoinhibition that occurs at the time of faint.
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Affiliation(s)
- Indu Taneja
- Department of Pediatrics, New York Medical College, Hawthorne, NY 10532, USA.
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