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Twenty-Four-Hour Urinary Sodium Excretion Predicts Therapeutic Effectiveness of Oral Rehydration Saline in Pediatric Vasovagal Syncope. CHILDREN (BASEL, SWITZERLAND) 2022; 9:children9070992. [PMID: 35883976 PMCID: PMC9321383 DOI: 10.3390/children9070992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/24/2022] [Accepted: 06/27/2022] [Indexed: 11/29/2022]
Abstract
The study was designed to explore whether 24-hour urinary sodium excretion could predict the therapeutic effectiveness of oral rehydration saline in pediatric cases of vasovagal syncope. Eighty children suffering from vasovagal syncope with oral rehydration saline treatment in Department of Pediatrics, Peking University First Hospital, China, were recruited into the study. They were followed up for 3 (2, 3) months after treatment. Pre-treatment demographic, clinical, head-up tilt test-based hemodynamic and laboratory variables were compared between responders and non-responders. After univariate analysis, variables with p value < 0.05 in the comparison between responders and non-responders were further analyzed by binary logistic regression analysis. Receiver operating characteristic (ROC) curve was conducted to assess the value in predicting effectiveness of oral rehydration saline treatment. The results showed that 33 cases were responders, and 47 were non-responders. Blood sodium (138 ± 2 mmol/L vs. 139 ± 2 mmol/L, p < 0.05) and pre-treatment 24-hour urinary sodium excretion (74 ± 29 mmol/24 h vs. 109 (93, 141) mmol/24 h, p < 0.001) were lower in responders than in non-responders. The baseline 24-hour urinary sodium excretion was positively correlated to the duration from tilting to the positive response appearance in head-up tilt test (r = 0.289, p < 0.01). The cut-off value of baseline 24-hour urinary sodium excretion of the therapeutic effectiveness of oral rehydration saline on vasovagal syncope cases was 83 mmol/24 h, yielding a sensitivity of 87% and a specificity of 73% with AUC of 0.842 (p < 0.001). In conclusion, 24-hour urinary sodium excretion could be a useful biomarker to predict the therapeutic response to oral rehydration saline in pediatric cases of vasovagal syncope.
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Leech MM, Herrick MD, Parnell KE, Rosenkranz KM. Dysautonomia following breast surgery: Disproportionate response to post-operative hematoma. Surg Open Sci 2022; 10:7-11. [PMID: 35789962 PMCID: PMC9249797 DOI: 10.1016/j.sopen.2022.05.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/11/2022] [Accepted: 05/18/2022] [Indexed: 11/08/2022] Open
Abstract
Background Up to 10% of patients undergoing breast surgery suffer from bleeding complications. Some experience severe hypotension and bradycardia of unclear etiology. Similar to the vasovagal hyperstimulation provoked by abdominal insufflation during laparoscopic surgery, we hypothesize that chest wall stretch from postoperative breast hematoma may mechanically stretch the vagus nerve, triggering dysautonomia disproportionate to the degree of blood loss. Methods A single-institution retrospective review of patients requiring reoperation for hematoma evacuation following breast surgery between 2011 and 2021 was performed. The relationship between hematoma volume and hemodynamic instability, as well as hematoma volume and vasovagal symptoms, was measured. Results Sixteen patients were identified. Average hematoma volume was 353 mL, and average minimum mean arterial pressure was 64 mm Hg (range: 34–102 mm Hg). Fifty-six percent of patients reported symptoms including dizziness, somnolence, and/or syncope. Accounting for body surface area, patients with larger hematomas had similar minimum mean arterial pressures compared to those with smaller hematomas, 55 and 73 mm Hg, respectively (P = .0943). However, patients in the large hematoma group experienced over 3 times as many vasovagal symptoms, 88% and 25%, respectively (P = .0095). Conclusion Patients with large hematomas reported significantly more vagal symptoms compared to those with small hematomas despite similar mean arterial pressures. In addition, the trend of lower mean arterial pressures and heart rates more closely resembles vagal hyperstimulation than hypovolemic shock. Early hematoma evacuation to relieve vagal nerve stretch and parasympatholytics to reverse dysautonomia are targeted interventions to consider in this patient population rather than fluids, vasopressors, and blood products that are used in cases of hemodynamic instability due to hypovolemia alone.
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Evaluating the Behavioural Responses of Healthy Newborn Calves to a Thoracic Squeeze. Animals (Basel) 2022; 12:ani12070840. [PMID: 35405830 PMCID: PMC8997037 DOI: 10.3390/ani12070840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/27/2022] [Accepted: 03/23/2022] [Indexed: 11/21/2022] Open
Abstract
Simple Summary Reports of calves born via caesarean section behaving abnormally have led to the application of a therapy called a ‘thoracic squeeze’ that has been used to ‘recover’ low-vigour neonates of other farmed mammal species. The squeeze involves looping a rope around the chest of the animal and pulling it taut, causing a state of reduced responsiveness. Once the squeeze is removed, low-vigour neonates are reported to immediately stand up and display normal behaviours. We aimed to characterise the behavioural responses of healthy newborn calves to a thoracic squeeze using two methods: a rope and an inflation cuff. In total, 13 of the 16 calves squeezed were induced into a state of reduced responsiveness, though their pedal and palpebral reflexes remained present in nearly all of the calves. For nearly half of the calves induced, the squeeze was discontinued before the end of the 10-min period due to spontaneous arousal or abnormal changes in their physiological status. The calves squeezed with the cuff appeared to lose posture and stop moving faster than the calves squeezed with the rope. This study demonstrates that healthy calves born without assistance respond similarly to the squeeze to other mammalian species, and it provides a foundation for the exploration of the mechanisms underlying these responses. Abstract A thoracic squeeze has been observed to cause low-vigour neonates of various farmed mammal species, including calves, to enter a state of reduced responsiveness. The removal of the squeeze causes rapid recovery and the expression of normal, healthy behaviours. However, the responses of healthy calves to a thoracic squeeze have not yet been characterized. The responses of 16 healthy newborn calves to a thoracic squeeze are described, along with the effect of the squeeze’s application method on the response. Calves aged between 12 and 36 h were subjected to the squeeze using a rope (n = 8) or an inflation cuff (n = 8). In total, 13 of the 16 calves were induced into a state of reduced responsiveness, though neural reflexes persisted in nearly all of them. The squeeze was discontinued for nearly half of those induced before the end of the 10-min period, either due to spontaneous arousal or physiological instability. Both methods of application were equally effective at inducing reduced responsiveness, though responses to the cuff appeared to be more rapid than those to the rope. These findings support previous research on piglets and foals, and suggest that the behavioural responses to a thoracic squeeze are generalised across neonates of precocial farmed mammals; the findings provide a foundation for further research exploring the mechanisms underlying the response and the benefits that its application may bring for the performance of husbandry procedures.
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Holdsworth SE, Kells NJ, Chidgey KL, Vallée E, Ward N, Mellor DJ, Beausoleil NJ. Characterisation of the Behavioural Effects of a Thoracic Squeeze in Healthy Newborn Piglets. Animals (Basel) 2021; 11:ani11082465. [PMID: 34438922 PMCID: PMC8388775 DOI: 10.3390/ani11082465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/12/2021] [Accepted: 08/18/2021] [Indexed: 11/16/2022] Open
Abstract
Simple Summary Firmly squeezing the chests of newborn foals and calves that are showing abnormal behaviours after birth causes them to enter a less-responsive state, characterised by lying down with eyes closed and no limb movements. Once the squeeze is removed, the newborns immediately ‘wake up’ and begin to display more normal behaviours. This response to the thoracic squeeze has also been observed in healthy, normally behaving foals. However, no studies have looked at the effects of the thoracic squeeze in healthy newborns of other mammalian species. We aimed to characterise the behavioural responses of healthy newborn piglets to a thoracic squeeze using the following two methods: a soft fabric rope, or a purpose-made inflation cuff. Behavioural data indicated that all piglets initially became less responsive, with reduced or absent reflex responses to a toe pinch or touch of the eyelid observed in over half of the piglets. The piglets squeezed with the inflation cuff appeared to enter a less-responsive state faster than the piglets squeezed with the rope. These findings suggest that the piglets responded to the thoracic squeeze in a similar way to healthy foals and that this may be a response conserved across multiple precocial mammalian species. Furthermore, the squeeze was found to be safe for inducing a less-responsive state in healthy piglets. This study provides a foundation for exploring the mechanisms underlying the responses to the thoracic squeeze and potential applications whilst performing husbandry procedures. Abstract A thoracic squeeze has been observed to cause both healthy and low vigour neonatal foals to enter a ‘less-responsive state’, characterised by loss of posture, eye closure and cessation of movement, from which they rapidly recover to express normal healthy behaviours when the squeeze is released. To date, there have been no systematic studies characterising the responses of healthy neonates of other mammalian species to a thoracic squeeze. We describe the responses of healthy newborn piglets (n = 17) to a standardised application of the thoracic squeeze and evaluate the effect of the method of squeeze application on the response. Neonatal piglets were squeezed around the chest with either a soft fabric rope as has been used in foals (n = 8) or a novel purpose-made inflation cuff (n = 9). Both methods were effective at inducing a less-responsive behavioural state in all piglets, with neural reflexes reduced or absent in over half of them. The inflation cuff appeared to induce the less-responsive state faster than the rope, and more piglets squeezed with the cuff remained in this state for the full 10-min squeeze. These findings suggest that the behavioural response of foals to thoracic squeezing can be generalised to neonates of other precocial mammalian species. This initial study provides a foundation for further research using the inflation cuff to explore mechanisms underlying the thoracic squeeze and ways in which it may be applied whilst performing husbandry procedures.
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Affiliation(s)
- Sophia E. Holdsworth
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand; (S.E.H.); (N.J.K.); (N.W.); (D.J.M.)
| | - Nikki J. Kells
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand; (S.E.H.); (N.J.K.); (N.W.); (D.J.M.)
| | - Kirsty L. Chidgey
- School of Agriculture and Environment, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand;
| | - Emilie Vallée
- EpiCentre, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand;
| | - Neil Ward
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand; (S.E.H.); (N.J.K.); (N.W.); (D.J.M.)
| | - David J. Mellor
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand; (S.E.H.); (N.J.K.); (N.W.); (D.J.M.)
| | - Ngaio J. Beausoleil
- Animal Welfare Science and Bioethics Centre, School of Veterinary Science, Massey University, Private Bag 11-222, Palmerston North 4442, New Zealand; (S.E.H.); (N.J.K.); (N.W.); (D.J.M.)
- Correspondence:
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Suspension syndrome: a potentially fatal vagally mediated circulatory collapse-an experimental randomized crossover trial. Eur J Appl Physiol 2019; 119:1353-1365. [PMID: 30895459 PMCID: PMC6517360 DOI: 10.1007/s00421-019-04126-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Accepted: 03/13/2019] [Indexed: 12/22/2022]
Abstract
Purpose Suspension syndrome describes a potentially life-threatening event during passive suspension on a rope. The pathophysiological mechanism is not fully understood and optimal treatment unknown. We aimed to elucidate the pathophysiology and to give treatment recommendations. Methods In this experimental, randomized crossover trial, 20 healthy volunteers were suspended in a sit harness for a maximum of 60 min, with and without prior climbing. Venous pooling was assessed by measuring the diameter of the superficial femoral vein (SFV), lower leg tissue oxygenation (StO2) and by determining localized bioelectrical impedance. Hemodynamic response was assessed by measuring heart rate, blood pressure, stroke volume, and left ventricular diameters. Signs and symptoms of pre-syncope were recorded. Results Twelve (30%) out of 40 tests were prematurely terminated due to pre-syncopal symptoms (mean 44.7 min, minimum 13.4, maximum 59.7). SFV diameter increased, StO2 and the capacitive resistance of the cells decreased indicating venous pooling. Heart rate and blood pressure did not change in participants without pre-syncope. In contrast, in participants experiencing pre-syncope, heart rate and blood pressure dropped immediately before the event. All symptoms dissolved and values returned to normal within 5 min with participants in a supine position. Conclusions Sudden pre-syncope during passive suspension in a harness was observed in 30% of the tests. Blood pools in the veins of the lower legs; however, a vagal mechanism finally leads to loss of consciousness. Time to pre-syncope is unpredictable and persons suspended on a rope should be rescued and put into a supine position as soon as possible. Electronic supplementary material The online version of this article (10.1007/s00421-019-04126-5) contains supplementary material, which is available to authorized users.
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Mahmudy F, Mousavi SH, Jouhari-Moghadam A, Mehrabi F. Syncope risk factors among military training soldiers; A case-control study. ARYA ATHEROSCLEROSIS 2018; 14:242-247. [PMID: 31143224 PMCID: PMC6527146 DOI: 10.22122/arya.v14i6.1872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Syncope is a transient brief loss of consciousness accompanied with loss of postural tone. Of common places in which people experience syncope, military barracks can be named where training soldiers spend their military courses. The current study aimed to assess etiology and risk factors of syncope among military training soldiers. METHODS This was a retrospective case-control study conducted on training soldiers of Army-501 hospital in Tehran, Iran, during the years 2017-2018. Cases were consisted of 50 soldiers who experienced syncope during military training, and controls were 150 soldiers who had not experienced syncope during their military training. Demographic data were recorded for cases and controls. RESULTS Members of case and control groups were not statistically different regarding age (P = 0.46) and height (P = 0.70). Logistic regression test was performed and considering crude model, weight [odds ratio (OR): 0.94; 95% of confidence interval (95%CI): 0.90-0.98], body mass index (BMI) (OR: 0.72; 95%CI: 0.61-0.85), standing duration (OR: 1.007; 95%CI: 1.00-1.01), history of syncope (OR: 15.47; 95%CI: 4.15-57.60), positive family history of syncope (OR: 5.94; 95%CI: 1.66-21.25), smoking (OR: 3.5; 95%CI: 1.54-7.91), medical problems (OR: 7.97; 95%CI: 1.98-32.17), anxiety (OR: 2.02; 95%CI: 1.13-4.26), stress (OR: 6.68; 95%CI: 3.28-13.57), and depression (OR: 4.25; 95%CI: 2.15-8.39) were detected as significant predictors of syncope occurrence. CONCLUSION Based on the findings of this study, lower BMI, positive history of syncope, smoking, depression, and stress were significant risk factors of syncope occurrence among training soldiers. Higher BMI has protective role in syncope occurrence.
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Affiliation(s)
- Farhad Mahmudy
- General Practitioner, Department of Cardiology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran
| | - Seyyed Hossein Mousavi
- Assistant Professor, Department of Cardiology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran,Correspondence to: Seyyed Hossein Mousavi,
| | - Adel Jouhari-Moghadam
- Assistant Professor, Department of Cardiology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran
| | - Farzad Mehrabi
- Assistant Professor, Department of Neurology, School of Medicine, AJA University of Medical Sciences, Tehran, Iran
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Stewart JM, Boris JR, Chelimsky G, Fischer PR, Fortunato JE, Grubb BP, Heyer GL, Jarjour IT, Medow MS, Numan MT, Pianosi PT, Singer W, Tarbell S, Chelimsky TC. Pediatric Disorders of Orthostatic Intolerance. Pediatrics 2018; 141:peds.2017-1673. [PMID: 29222399 PMCID: PMC5744271 DOI: 10.1542/peds.2017-1673] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/06/2017] [Indexed: 01/18/2023] Open
Abstract
Orthostatic intolerance (OI), having difficulty tolerating an upright posture because of symptoms or signs that abate when returned to supine, is common in pediatrics. For example, ∼40% of people faint during their lives, half of whom faint during adolescence, and the peak age for first faint is 15 years. Because of this, we describe the most common forms of OI in pediatrics and distinguish between chronic and acute OI. These common forms of OI include initial orthostatic hypotension (which is a frequently seen benign condition in youngsters), true orthostatic hypotension (both neurogenic and nonneurogenic), vasovagal syncope, and postural tachycardia syndrome. We also describe the influences of chronic bed rest and rapid weight loss as aggravating factors and causes of OI. Presenting signs and symptoms are discussed as well as patient evaluation and testing modalities. Putative causes of OI, such as gravitational and exercise deconditioning, immune-mediated disease, mast cell activation, and central hypovolemia, are described as well as frequent comorbidities, such as joint hypermobility, anxiety, and gastrointestinal issues. The medical management of OI is considered, which includes both nonpharmacologic and pharmacologic approaches. Finally, we discuss the prognosis and long-term implications of OI and indicate future directions for research and patient management.
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Affiliation(s)
| | | | | | | | - John E. Fortunato
- Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, Illinois
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Sieck DC, Ely MR, Romero SA, Luttrell MJ, Abdala PM, Halliwill JR. Post-exercise syncope: Wingate syncope test and visual-cognitive function. Physiol Rep 2017; 4:4/16/e12883. [PMID: 27550986 PMCID: PMC5002906 DOI: 10.14814/phy2.12883] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 07/15/2016] [Indexed: 01/23/2023] Open
Abstract
Adequate cerebral perfusion is necessary to maintain consciousness in upright humans. Following maximal anaerobic exercise, cerebral perfusion can become compromised and result in syncope. It is unknown whether post-exercise reductions in cerebral perfusion can lead to visual-cognitive deficits prior to the onset of syncope, which would be of concern for emergency workers and warfighters, where critical decision making and intense physical activity are combined. Therefore, the purpose of this experiment was to determine if reductions in cerebral blood velocity, induced by maximal anaerobic exercise and head-up tilt, result in visual-cognitive deficits prior to the onset of syncope. Nineteen sedentary to recreationally active volunteers completed a symptom-limited 60° head-up tilt for 16 min before and up to 16 min after a 60 sec Wingate test. Blood velocity of the middle cerebral artery was measured using transcranial Doppler ultrasound and a visual decision-reaction time test was assessed, with independent analysis of peripheral and central visual field responses. Cerebral blood velocity was 12.7 ± 4.0% lower (mean ± SE; P < 0.05) after exercise compared to pre-exercise. This was associated with a 63 ± 29% increase (P < 0.05) in error rate for responses to cues provided to the peripheral visual field, without affecting central visual field error rates (P = 0.46) or decision-reaction times for either visual field. These data suggest that the reduction in cerebral blood velocity following maximal anaerobic exercise contributes to visual-cognitive deficits in the peripheral visual field without an apparent affect to the central visual field.
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Affiliation(s)
- Dylan C Sieck
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Matthew R Ely
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - Steven A Romero
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | | | - Pedro M Abdala
- Department of Human Physiology, University of Oregon, Eugene, Oregon
| | - John R Halliwill
- Department of Human Physiology, University of Oregon, Eugene, Oregon
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Chowdhury T, Schaller B. The negative chronotropic effect during lumbar spine surgery: A systemic review and aggregation of an emerging model of spinal cardiac reflex. Medicine (Baltimore) 2017; 96:e5436. [PMID: 28072687 PMCID: PMC5228647 DOI: 10.1097/md.0000000000005436] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Hemodynamic perturbations in spine surgeries are predominantly reported in cervical and thoracic level procedures. The literature related to negative cardiovascular changes (decrease of heart rate and blood pressure) in lumbar spine procedures is still scarce and only highlighted in few case reports/letters until now. METHODS With the help of a systematic literature review with predefined criteria, we, therefore, examined and synthesized here the probable underlying common cause of these hemodynamic disturbances in lumbar spine surgeries. Data aggregation to a model was done by a case survey method and established by a cause-effect relationship. RESULTS There are only 5 cases that met our strict predefined criteria and that were aggregated to an emergent model of an autonomous reflex arc. CONCLUSION This review and consecutive data aggregation provides, for the first time, a concept of spinal cardiac reflex in lumbar spine surgeries.
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Affiliation(s)
- Tumul Chowdhury
- Department of Anesthesiology and Perioperative Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Bernhard Schaller
- Department of Anesthesiology and Perioperative Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
- Department of Research, University of Southampton, Southampton, UK
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Takahagi VCM, Costa DC, Crescêncio JC, Gallo L. Physical training as non-pharmacological treatment of neurocardiogenic syncope. Arq Bras Cardiol 2014; 102:288-94. [PMID: 24714795 PMCID: PMC3987313 DOI: 10.5935/abc.20140021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 10/09/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Characterized as a sudden and temporary loss of consciousness and postural tone, with quick and spontaneous recovery, syncope is caused by an acute reduction of systemic arterial pressure and, therefore, of cerebral blood flow. Unsatisfactory results with the use of drugs allowed the nonpharmacological treatment of neurocardiogenic syncope was contemplated as the first therapeutic option. OBJECTIVES To compare, in patients with neurocardiogenic syncope, the impact of a moderate intensity aerobic physical training (AFT) and a control intervention on the positivity of head-up tilting test (HUT) and orthostatic tolerance time. METHODS Were studied 21 patients with a history of recurrent neurocardiogenic syncope and HUT. The patients were randomized into: trained group (TG), n = 11, and control group (CG), n = 10. The TG was submitted to 12 weeks of AFT supervised, in cycle ergometer, and the CG to a control procedure that consisted in 15 minutes of stretching and 15 minutes of light walk. RESULTS The TG had a positive effect to physical training, with a significant increase in peak oxygen consumption. The CG did not show any statistically significant change before and after the intervention. After the intervention period, 72.7% of the TG sample had negative results to the HUT, not having syncope in the revaluation. CONCLUSION The program of supervised aerobic physical training for 12 weeks was able to reduce the number of positive HUT, as it was able to increase tolerance time in orthostatic position during the HUT after the intervention period.
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Affiliation(s)
- Vanessa Cristina Miranda Takahagi
- Mailing Address: Vanessa Cristina Miranda Takahagi, Divisão de
Cardiologia HCFMRP-USP - Av. Bandeirantes, 3900, Monte Alegre. Postal Code 14049-900,
Ribeirão Preto, SP - Brazil. E-mail:
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11
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Blood pressure regulation X: what happens when the muscle pump is lost? Post-exercise hypotension and syncope. Eur J Appl Physiol 2013; 114:561-78. [PMID: 24197081 DOI: 10.1007/s00421-013-2761-1] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 10/22/2013] [Indexed: 01/19/2023]
Abstract
Syncope which occurs suddenly in the setting of recovery from exercise, known as post-exercise syncope, represents a failure of integrative physiology during recovery from exercise. We estimate that between 50 and 80% of healthy individuals will develop pre-syncopal signs and symptoms if subjected to a 15-min head-up tilt following exercise. Post-exercise syncope is most often neurally mediated syncope during recovery from exercise, with a combination of factors associated with post-exercise hypotension and loss of the muscle pump contributing to the onset of the event. One can consider the initiating reduction in blood pressure as the tip of the proverbial iceberg. What is needed is a clear model of what lies under the surface; a model that puts the observational variations in context and provides a rational framework for developing strategic physical or pharmacological countermeasures to ultimately protect cerebral perfusion and avert loss of consciousness. This review summarizes the current mechanistic understanding of post-exercise syncope and attempts to categorize the variation of the physiological processes that arise in multiple exercise settings. Newer investigations into the basic integrative physiology of recovery from exercise provide insight into the mechanisms and potential interventions that could be developed as countermeasures against post-exercise syncope. While physical counter maneuvers designed to engage the muscle pump and augment venous return are often found to be beneficial in preventing a significant drop in blood pressure after exercise, countermeasures that target the respiratory pump and pharmacological countermeasures based on the involvement of histamine receptors show promise.
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12
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Lacewell AN, Buck TM, Romero SA, Halliwill JR. Postexercise syncope: Wingate syncope test and effective countermeasure. Exp Physiol 2013; 99:172-86. [PMID: 24078670 DOI: 10.1113/expphysiol.2013.075333] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Altered systemic haemodynamics following exercise can compromise cerebral perfusion and result in syncope. As the Wingate anaerobic test often induces presyncope, we hypothesized that a modified Wingate test could form the basis of a novel model for the study of postexercise syncope and a test bed for potential countermeasures. Along these lines, breathing through an impedance threshold device has been shown to increase tolerance to hypovolaemia, and could prove beneficial in the setting of postexercise syncope. Therefore, we hypothesized that a modified Wingate test followed by head-up tilt would produce postexercise syncope, and that breathing through an impedance threshold device (countermeasure) would prevent postexercise syncope in healthy individuals. Nineteen recreationally active men and women underwent a 60 deg head-up tilt during recovery from the Wingate test while arterial pressure, heart rate, end-tidal CO2 and cerebral tissue oxygenation were measured on a control day and a countermeasure day. The duration of tolerable tilt was increased by a median time of 3 min 48 s with countermeasure in comparison to the control (P < 0.05), and completion of the tilt test increased from 42 to 67% with the countermeasure. During the tilt, mean arterial pressure was greater (108.0 ± 4.1 versus 100.4 ± 2.4 mmHg; P < 0.05) with the countermeasure in comparison to the control. These data suggest that the Wingate syncope test produces a high incidence of presyncope, which is sensitive to countermeasures such as inspiratory impedance.
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Affiliation(s)
- Alisha N Lacewell
- J. R. Halliwill: 122 Esslinger Hall, 1240 University of Oregon, Eugene, OR 97403-1240, USA.
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13
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Stewart JM. Update on the theory and management of orthostatic intolerance and related syndromes in adolescents and children. Expert Rev Cardiovasc Ther 2013; 10:1387-99. [PMID: 23244360 DOI: 10.1586/erc.12.139] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Orthostasis means standing upright. One speaks of orthostatic intolerance (OI) when signs, such as hypotension, and symptoms, such as lightheadedness, occur when upright and are relieved by recumbence. The experience of transient mild OI is part of daily life. 'Initial orthostatic hypotension' on rapid standing is a normal form of OI. However, other people experience OI that seriously interferes with quality of life. These include episodic acute OI, in the form of postural vasovagal syncope, and chronic OI, in the form of postural tachycardia syndrome. Less common is neurogenic orthostatic hypotension, which is an aspect of autonomic failure. Normal orthostatic physiology and potential mechanisms for OI are discussed, including forms of sympathetic hypofunction, forms of sympathetic hyperfunction and OI that results from regional blood volume redistribution. General and specific treatment options are proposed.
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Affiliation(s)
- Julian M Stewart
- Departments of Pediatrics, Physiology and Medicine, The Maria Fareri Childrens Hospital and New York Medical College, Valhalla, NY, USA.
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Abstract
The autonomic nervous system, adequate blood volume, and intact skeletal and respiratory muscle pumps are essential components for rapid cardiovascular adjustments to upright posture (orthostasis). Patients lacking sufficient blood volume or having defective sympathetic adrenergic vasoconstriction develop orthostatic hypotension (OH), prohibiting effective upright activities. OH is one form of orthostatic intolerance (OI) defined by signs, such as hypotension, and symptoms, such as lightheadedness, that occur when upright and are relieved by recumbence. Mild OI is commonly experienced during intercurrent illnesses and when standing up rapidly. The latter is denoted "initial OH" and represents a normal cardiovascular adjustment to the blood volume shifts during standing. Some people experience episodic acute OI, such as postural vasovagal syncope (fainting), or chronic OI, such as postural tachycardia syndrome, which can significantly reduce quality of life. The lifetime incidence of ≥1 fainting episodes is ∼40%. For the most part, these episodes are benign and self-limited, although frequent syncope episodes can be debilitating, and injury may occur from sudden falls. In this article, mechanisms for OI having components of adrenergic hypofunction, adrenergic hyperfunction, hyperpnea, and regional blood volume redistribution are discussed. Therapeutic strategies to cope with OI are proposed.
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Affiliation(s)
- Julian M. Stewart
- Departments of Pediatrics, Physiology, and Medicine, The Maria Fareri Children’s Hospital and New York Medical College, Valhalla, New York
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Simulation of exercise-induced syncope in a heart model with severe aortic valve stenosis. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2012; 2012:138401. [PMID: 23251225 PMCID: PMC3521475 DOI: 10.1155/2012/138401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 10/08/2012] [Accepted: 10/15/2012] [Indexed: 01/17/2023]
Abstract
Severe aortic valve stenosis (AVS) can cause an exercise-induced reflex syncope (RS). The precise mechanism of this syncope is not known. The changes in hemodynamics are variable, including arrhythmias and myocardial ischemia, and one of the few consistent changes is a sudden fall in systemic and pulmonary arterial pressures (suggesting a reduced vascular resistance) followed by a decline in heart rate. The contribution of the cardioinhibitory and vasodepressor components of the RS to hemodynamics was evaluated by a computer model. This lumped-parameter computer simulation was based on equivalent electronic circuits (EECs) that reflect the hemodynamic conditions of a heart with severe AVS and a concomitantly decreased contractility as a long-term detrimental consequence of compensatory left ventricular hypertrophy. In addition, the EECs model simulated the resetting of the sympathetic nervous tone in the heart and systemic circuit during exercise and exercise-induced syncope, the fluctuating intra-thoracic pressure during respiration, and the passive relaxation of ventricle during diastole. The results of this simulation were consistent with the published case reports of exertional syncope in patients with AVS. The value of the EEC model is its ability to quantify the effect of a selective and gradable change in heart rate, ventricular contractility, or systemic vascular resistance on the hemodynamics during an exertional syncope in patients with severe AVS.
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Abstract
Sympathetic circulatory control is key to the rapid cardiovascular adjustments that occur within seconds of standing upright (orthostasis) and which are required for bipedal stance. Indeed, patients with ineffective sympathetic adrenergic vasoconstriction rapidly develop orthostatic hypotension, prohibiting effective upright activities. One speaks of orthostatic intolerance (OI) when signs, such as hypotension, and symptoms, such as lightheadedness, occur when upright and are relieved by recumbence. The experience of transient mild OI is part of daily life. However, many people experience episodic acute OI as postural faint or chronic OI in the form of orthostatic tachycardia and orthostatic hypotension that significantly reduce the quality of life. Potential mechanisms for OI are discussed including forms of sympathetic hypofunction, forms of sympathetic hyperfunction, and OI that results from regional blood volume redistribution attributable to regional adrenergic hypofunction.
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Affiliation(s)
- Julian M Stewart
- Departments of Physiology, Pediatrics and Medicine, New York Medical College, Valhalla, NY, USA. mail:
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Schroeder C, Tank J, Heusser K, Diedrich A, Luft FC, Jordan J. Physiological phenomenology of neurally-mediated syncope with management implications. PLoS One 2011; 6:e26489. [PMID: 22046292 PMCID: PMC3201957 DOI: 10.1371/journal.pone.0026489] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 09/28/2011] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Due to lack of efficacy in recent trials, current guidelines for the treatment of neurally-mediated (vasovagal) syncope do not promote cardiac pacemaker implantation. However, the finding of asystole during head-up tilt -induced (pre)syncope may lead to excessive cardioinhibitory syncope diagnosis and treatment with cardiac pacemakers as blood pressure is often discontinuously measured. Furthermore, physicians may be more inclined to implant cardiac pacemakers in older patients. We hypothesized that true cardioinhibitory syncope in which the decrease in heart rate precedes the fall in blood pressure is a very rare finding which might explain the lack of efficacy of pacemakers in neurally-mediated syncope. METHODS We studied 173 consecutive patients referred for unexplained syncope (114 women, 59 men, 42 ± 1 years, 17 ± 2 syncopal episodes). All had experienced (pre)syncope during head-up tilt testing followed by additional lower body negative suction. We classified hemodynamic responses according to the modified Vasovagal Syncope International Study (VASIS) classification as mixed response (VASIS I), cardioinhibitory without (VASIS IIa) or with asystole (VASIS IIb), and vasodepressor (VASIS III). Then, we defined the exact temporal relationship between hypotension and bradycardia to identify patients with true cardioinhibitory syncope. RESULTS Of the (pre)syncopal events during tilt testing, 63% were classified as VASIS I, 6% as VASIS IIb, 2% as VASIS IIa, and 29% as VASIS III. Cardioinhibitory responses (VASIS class II) progressively decreased from the youngest to the oldest age quartile. With more detailed temporal analysis, blood pressure reduction preceded the heart-rate decrease in all but six individuals (97%) overall and in 10 out of 11 patients with asystole (VASIS IIb). CONCLUSIONS Hypotension precedes bradycardia onset during head-up tilt-induced (pre)syncope in the vast majority of patients, even in those classified as cardioinhibitory syncope according to the modified VASIS classification. Furthermore, cardioinhibitory syncope becomes less frequent with increasing age.
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Affiliation(s)
- Christoph Schroeder
- Institute for Clinical Pharmacology, Hannover Medical School, Hannover, Germany
- Experimental Clinical Research Center, Medical University Charité and Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Jens Tank
- Institute for Clinical Pharmacology, Hannover Medical School, Hannover, Germany
| | - Karsten Heusser
- Institute for Clinical Pharmacology, Hannover Medical School, Hannover, Germany
| | - André Diedrich
- Division of Clinical Pharmacology, Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Friedrich C. Luft
- Experimental Clinical Research Center, Medical University Charité and Max-Delbrueck Center for Molecular Medicine, Berlin, Germany
| | - Jens Jordan
- Institute for Clinical Pharmacology, Hannover Medical School, Hannover, Germany
- * E-mail:
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Wieling W, Rozenberg J, Go-Schön IK, Karemaker JM, Westerhof BE, Jardine DL. Hemodynamic mechanisms underlying prolonged post-faint hypotension. Clin Auton Res 2011; 21:405-13. [PMID: 21796352 PMCID: PMC3210950 DOI: 10.1007/s10286-011-0134-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 06/09/2011] [Indexed: 11/29/2022]
Abstract
OBJECTIVE During hypotension induced by tilt-table testing, low presyncopal blood pressure (BP) usually recovers within 1 min after tilt back. However, in some patients prolonged post faint hypotension (PPFH) is observed. We assessed the hemodynamics underlying PPFH in a retrospective study. METHODS Seven patients (2 females, aged 31-72 years) experiencing PPFH were studied. PPFH was defined as a systolic BP below 85 mmHg for at least 2 min after tilt back. In 6 out of 7 presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60° head-up tilt position following head-up tilt for 20 min. Continuous BP was monitored and stroke volume (SV) was computed from pressure pulsations. Cardiac output (CO) was calculated from SV × heart rate (HR); and total peripheral resistance (TPR) from mean BP/CO. Left ventricular contractility was estimated by dP/dt (max) of finger pressure pulse. RESULTS Systolic BP (SYS), diastolic BP (DIAS) and HR during PPFH were lower compared to baseline: SYS 75 ± 14 versus 121 ± 18 mmHg, DIAS 49 ± 9 versus 71 ± 9 mmHg and HR 52 ± 14 versus 67 ± 12 beats/min (p < 0.05). Marked hypotension was associated with a 47% fall in CO 3.1 ± 0.6 versus 5.9 ± 1.3 L/min (p < 0.05) and decreases in dP/dt, 277 ± 77 versus 759 ± 160 mmHg/s (p < 0.05). The difference in TPR was not significant 1.1 ± 0.3 versus 1.0 ± 0.3 MU (p = 0.229). In four patients, we attempted to treat PPFH by 30° head-down tilt. This intervention increased SYS only slightly (to 89 ± 12 mmHg). INTERPRETATION PPFH seems to be mediated by severe cardiac depression.
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Affiliation(s)
- Wouter Wieling
- Department of Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands.
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Affiliation(s)
- Michael J Joyner
- Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
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Tan MP, Parry SW. Vasovagal Syncope in the Older Patient. J Am Coll Cardiol 2008; 51:599-606. [DOI: 10.1016/j.jacc.2007.11.025] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Revised: 11/08/2007] [Accepted: 11/12/2007] [Indexed: 01/14/2023]
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Ebden MJ, Tarassenko L, Payne SJ, Darowski A, Price JD. Time-frequency analysis of the ECG in the diagnosis of vasovagal syndrome in older people. CONFERENCE PROCEEDINGS : ... ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL CONFERENCE 2007; 2006:290-3. [PMID: 17271667 DOI: 10.1109/iembs.2004.1403149] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Smoothed Pseudo Wigner-Ville Distribution (SPWVD) is used for the time-frequency analysis of variations in RR interval. A novel technique to determine the smoothing window lengths is implemented, and a new heart rate variability (HRV) metric is developed, instantaneous center frequency variability (ICFV), which uses the time-frequency map generated by the SPWVD. The technique is then applied to 50 patients with unexplained falls and age > 60, undergoing head-upright tilt table testing (HUT). Eighteen of the patients were diagnosed with vasovagal syndrome. Attempts at syncope prediction using the new metric is an improvement on traditional techniques: an ICFV less than 0.07 Hz from 90 s to 180 s after tilt is predictive of a negative test (negative predictive value: 0.77). The comorbidity and autonomic degeneration present in elderly patients are thought to be responsible for lowering the negative predictive value.
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Affiliation(s)
- M J Ebden
- Dept. of Eng. Sci., Oxford Univ., UK
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Joyner MJ, Schrage WG, Eisenach JH. Control of Blood Pressure—Normal and Abnormal. Neurobiol Dis 2007. [DOI: 10.1016/b978-012088592-3/50093-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Gracie J, Newton JL, Norton M, Baker C, Freeston M. The role of psychological factors in response to treatment in neurocardiogenic (vasovagal) syncope. Europace 2006; 8:636-43. [PMID: 16864617 DOI: 10.1093/europace/eul073] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
AIMS Studies have established a link between vasovagal syncope (VVS) and anxiety, depression, and functional impairment. This study examines the prevalence of psychological problems in patients with VVS and whether non-responders are psychologically different from those whose symptoms respond to conservative treatment. METHODS AND RESULTS Subjects with tilt-confirmed VVS completed the hospital anxiety and depression scale (HADS) (measures current levels of anxiety and depression) and the syncope functional status questionnaire (SFSQ) (syncope-specific quality-of-life measure) and participated in a semi-structured interview to ascertain potential triggers, thought content, and coping strategies. In this study, 41 subjects participated. There was no difference in gender and age duration of symptoms between responders (n=21) and non-responders (n=20). Non-responders were significantly more anxious (P=0.003) and depressed (P=0.003) and had a higher level of state (P=0.008) and trait (P=0.004) anxiety than responders. Non-responders reported more fear/worry (P=0.02), a significantly higher degree of impairment owing to syncope (P=0.01), and a greater number of perceived triggers (P=0.039); on average, participants reported eight negative thoughts about the consequences of VVS, with particular emphasis on threats of physical harm or death. Non-responders had higher levels of avoidance/protection coping and rumination. CONCLUSION This study has confirmed that patients with VVS have a significant degree of psychological distress, which is worthy of consideration in its own right, out with management purely aimed at reducing syncopal or pre-syncopal symptoms. Further, this distress may actually influence the natural history of what is a chronic relapsing condition and may in fact be more relevant to the patient than the number of syncopal episodes that they are experiencing.
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Affiliation(s)
- Jennifer Gracie
- Department of Psychology, Royal Victoria Infirmary, Newcastle NE1 4LP, UK
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Schroeder C, Birkenfeld AL, Mayer AF, Tank J, Diedrich A, Luft FC, Jordan J. Norepinephrine Transporter Inhibition Prevents Tilt-Induced Pre-Syncope. J Am Coll Cardiol 2006; 48:516-22. [PMID: 16875978 DOI: 10.1016/j.jacc.2006.04.073] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 03/10/2006] [Accepted: 04/10/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVES We tested the hypothesis that pharmacological norepinephrine reuptake transporter (NET) inhibition delays the onset of head-up tilt-induced presyncope in healthy subjects. BACKGROUND Treatment of neurally mediated syncope is unsatisfactory. In a previous study in a small number of healthy subjects, pharmacologic NET inhibition delayed the onset of head-up tilt-induced pre-syncope. METHODS We combined data sets from 3 substudies comprising 51 healthy subjects without a history of syncope. In a double-blind, randomized, cross-over fashion, subjects underwent 2 head-up tilt tests, once with placebo and once with a NET inhibitor (sibutramine or reboxetine). Tilt testing was prematurely ended when pre-syncopal symptoms such as dizziness, nausea, or visual disturbances occurred together with a decrease in blood pressure and/or heart rate. RESULTS The mean tolerated tilt test duration was 29 +/- 2 min with placebo and 35 +/- 1 min with NET inhibition (p = 0.001). The odds ratio for premature abortion of head-up tilt testing was 0.22 (95% confidence interval 0.09 to 0.55, p < 0.001) in favor of NET inhibition. Norepinephrine reuptake transporter inhibition elicited a pressor response and increased upright heart rate. CONCLUSIONS In healthy subjects, NET inhibition prevents tilt-induced neurally mediated (pre)syncope. Therefore, NET inhibition may be a worthwhile target of drug intervention for larger trials in highly symptomatic patients with neurally mediated syncope.
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Affiliation(s)
- Christoph Schroeder
- Franz-Volhard Clinical Research Center, Medical Faculty of the Charité and HELIOS Klinikum, Berlin, Germany
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Wright CI, Kroner CI, Draijer R. Non-invasive methods and stimuli for evaluating the skin's microcirculation. J Pharmacol Toxicol Methods 2006; 54:1-25. [PMID: 16256378 DOI: 10.1016/j.vascn.2005.09.004] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Accepted: 09/21/2005] [Indexed: 11/17/2022]
Abstract
Vessels in the skin are arranged into superficial and deep horizontal plexuses and they are involved in thermoregulation, oxygen and nutritional support. The skin has a large number of functions and broad appeal spanning basic mechanistic and clinical research. Indeed, the skin can be used as a marker of normal and impaired vascular control and, owing to its accessibility and frequent involvement, is easy to investigate non-invasively. A large number of non-invasive methods are available for investigating the skin, ranging from those that permit the visualisation of microvessels, to those that monitor blood flow or one of its derivatives (e.g., skin temperature and transcutaneous oxygen). Such methods can be combined with non-invasive, dynamic stimuli (e.g., the use of cold or warm stimuli, activation of the peripheral nervous system or local neuronal systems, and the topical application of vasoactive drugs) and this potentially enables the differentiation of underlying disorders (e.g., primary from secondary Raynaud's phenomenon) and also to quantify changes over time or following intervention. The present article outlines the non-invasive methods and dynamic tests that can be used to investigate the microcirculation of the skin.
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Affiliation(s)
- C I Wright
- Unilever Food and Health Research Institute, Unilever R&D Vlaardingen, Olivier van Noortlaan 120, PO Box 114, 3130 AC Vlaardingen, The Netherlands.
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Synkope im Kindes- und Jugendalter. Monatsschr Kinderheilkd 2006. [DOI: 10.1007/s00112-006-1339-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Katori M, Majima M. A missing link between a high salt intake and blood pressure increase. J Pharmacol Sci 2006; 100:370-90. [PMID: 16651701 DOI: 10.1254/jphs.crj06003x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
It is widely accepted that a high sodium intake triggers blood pressure rise. However, only one-third of the normotensive subjects were reported to show salt-sensitivity in their blood pressure. Many factors have been proposed as causes of salt-sensitive hypertension, but none of them provides a satisfactory explanation. We propose, on the basis of accumulated data, that the reduced activity of the kallikrein-kinin system in the kidney may provide this link. Renal kallikrein is secreted by the distal connecting tubular cells and all kallikrein-kinin system components are distributed along the collecting ducts in the distal nephron. Bradykinin generated is immediately destroyed by carboxypeptidase Y-like exopeptidase and neutral endopeptidase, both quite independent from the kininases in plasma, such as angiotensin converting enzyme. The salt-sensitivity of the blood pressure depends largely upon ethnicity and potassium intake. Interestingly, potassium and ATP-sensitive potassium (K(ATP)) channel blockers accelerate renal kallikrein secretion and suppress blood pressure rises in animal hypertension models. Measurement of urinary kallikrein may become necessary in salt-sensitive normotensive and hypertensive subjects. Furthermore, pharmaceutical development of renal kallikrein releasers, such as K(ATP) channel blockers, and renal kininase inhibitors, such as ebelactone B, may lead to the development of novel antihypertensive drugs.
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Affiliation(s)
- Makoto Katori
- Department of Pharmacology, Kitasato University School of Medicine, Kanagawa, Japan.
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Fortrat JO, Lemarie C, Bellard E, Victor J. Do we need a reflex tachycardia to stand up? PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2005; 28:962-7. [PMID: 16176536 DOI: 10.1111/j.1540-8159.2005.00216.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Sophisticated atrio-ventricular pacing models are designed to integrate the pacemaker into cardiovascular autonomic control to react appropriately to the cardiovascular demands. Such an approach might be beneficial for patients with vasovagal responses to counterbalance the upright fall in arterial blood pressure by a pacing rate increase. We hypothesized that this approach would improve the cardiovascular response to standing in comparison with a regular pacing mode. METHODS Two 5-minute tilt tests were performed in a random order in 5 patients with a pacemaker (CLS-INOS(2)) for sinus node disease and atrio-ventricular block. One tilt test was performed in fixed pacing rate (DDD), the other one was performed in close loop stimulation (CLS), which allowed an upright rate-rise pacing. Heart rate, systolic blood pressure, and cardiac output (modelflow) were recorded on a beat-by-beat basis. RESULTS Changes of systolic blood pressure and cardiac output in response to upright posture were not significantly different between DDD and CLS modes (2.7 +/- 13.2 vs 10.1 +/- 12.9 mmHg and -0.8 +/- 0.3 vs -1.1 +/- 0.4 L/min, respectively). But upright posture led to a tachycardia of more than 30 bpm in 3 patients in CLS mode and to a fall in systolic blood pressure greater than 20 mmHg in 3 patients in CLS mode and only in one patient in DDD mode. CONCLUSION Systolic blood pressure and cardiac output are not improved by the upright tachycardia and upright blood pressure response is actually worsened when an upright rate-rise pacing is used. Thus, it appears that tachycardia alone cannot compensate for an upright fall in blood pressure.
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Affiliation(s)
- Jacques-Olivier Fortrat
- Laboratoire de Physiologie, Faculté de Médecine, Centre Hospitalo-Universitaire, Faculté de Médecine, 49045 Angers Cedex, France.
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Prakash ES. When the heart is stopped for good: hypotension-bradycardia paradox revisited. ADVANCES IN PHYSIOLOGY EDUCATION 2005; 29:15-20. [PMID: 15722267 DOI: 10.1152/advan.00027.2004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In vasovagal syncope, occurrence of bradycardia/asystole in the wake of hypotension has often been considered paradoxical. The major objective of this teaching module is to critically examine the pathophysiological mechanism and significance of the hypotension-bradycardia paradox unique to this condition. We narrate here how we discussed the pathophysiology of vasovagal syncope in a large classroom session attended by 275 doctors and medical students. A case study was used to describe the typical clinical presentation of vasovagal syncope. The pathophysiological mechanisms involved were then discussed systematically using a series of open-ended questions. We made it clear 1) that the occurrence of bradycardia or asystole in the face of acute severe hypotension is a mechanism to possibly minimize further blood loss, prevent myocardial damage, and increase ventricular filling; and 2) that fainting, which occurs as a consequence of this, is a homeostatic mechanism that serves to restore venous return and cerebral blood flow before blood pressure is normalized by neural reflex mechanisms. Eighty-four percent of participants reported that they were satisfied with the session. The information contained herein could be used to explain to any suitable audience the neural regulation of blood pressure in the face of acute severe hypotension and the pathophysiology of vasovagal syncope.
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Affiliation(s)
- E S Prakash
- Department of Physiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India.
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Krediet CTP, Wilde AAM, Halliwill JR, Wieling W. Syncope during exercise, documented with continuous blood pressure monitoring during ergometer testing. Clin Auton Res 2005; 15:59-62. [PMID: 15768206 DOI: 10.1007/s10286-005-0241-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2004] [Accepted: 11/16/2004] [Indexed: 11/29/2022]
Abstract
A 27-year old female had one episode of transient loss of consciousness and several of near-unconsciousness during strenuous exercise and sexual activity. Episodes started with abdominal discomfort or nausea and light headedness. Unconsciousness never exceeded one minute. When trying to stand up, she felt she would lose consciousness again. We performed a bicycle ergometer exercise test, continuously monitoring blood pressure via non-invasive finger photoplethysmography (Finometer, FMS, The Netherlands). Beat-to-beat changes in stroke volume, cardiac output and total peripheral resistance were calculated using Modelflow (FMS, The Netherlands). At a power of 140 W, the patient reported being near exhaustion; shortly after this she reported nausea. She stopped cycling 30 s later, then saw "black spots" and felt an oncoming loss of consciousness. Dismounting the ergometer and squatting provided immediate relief from symptoms. Symptoms during the test were similar to those during previous episodes. The diagnosis was exercise-induced vasovagal reactions. This is the first report that documents the beat-to-beat changes in blood pressure, stroke volume and total peripheral resistance during exercise-induced vasovagal syncope. It illustrates the usefulness of combining exercise testing with continuous non-invasive blood pressure monitoring in the diagnostic work-up of exercise-induced syncope, and shows the therapeutic value of squatting to prevent loss of consciousness in exercise-related vasovagal syncope.
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Affiliation(s)
- C T Paul Krediet
- Academic Medical Center/University of Amsterdam, Dept. of Internal Medicine, F4-222, Meibergdreef 9, 1105AZ, Amsterdam, The Netherlands.
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Sapin SO. Autonomic syncope in pediatrics: a practice-oriented approach to classification, pathophysiology, diagnosis, and management. Clin Pediatr (Phila) 2004; 43:17-23. [PMID: 14968889 DOI: 10.1177/000992280404300103] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
This paper presents a practice-oriented approach to the problem of syncope in pediatrics. Autonomic syncope is the major etiologic category in pediatrics and consists of 2 types: reflex and dysautonomic. The latter type is rare in pediatrics. Reflex syncope has 4 subtypes: neurocardiogenic, central, situational, and cerebral. Neurocardiogenic syncope, the most common subtype, is easily diagnosed by taking a careful, detailed history; identifying diagnostic red flags; performing a complete physical examination; and ordering a minimum of laboratory tests. Patient and parent education is essential, and usually, without medication, outcomes are good.
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Affiliation(s)
- Samuel O Sapin
- Department of Pediatrics, Division of Cardiology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
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Julu POO, Cooper VL, Hansen S, Hainsworth R. Cardiovascular regulation in the period preceding vasovagal syncope in conscious humans. J Physiol 2003; 549:299-311. [PMID: 12679368 PMCID: PMC2342918 DOI: 10.1113/jphysiol.2002.036715] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
To study cardiovascular control in the period leading to vasovagal syncope we monitored beat-to-beat blood pressure, heart rate (HR) and forearm blood flow in 14 patients with posturally related syncope, from supine through to tilt-induced pre-syncope. Signals of arterial blood pressure (BP) from a Finapres photoplethysmograph and an electrocardiograph (ECG) were fed into a NeuroScope system for continuous analysis. Non-invasive indices of cardiac vagal tone (CVT) and cardiac sensitivity to baroreflex (CSB) were derived on a beat-to-beat basis from these data. Brachial vascular resistance (VR) was assessed intermittently from brachial blood flow velocity (Doppler ultrasound) divided by mean arterial pressure (MAP). Patients underwent a progressive orthostatic stress test, which continued to pre-syncope and consisted of 20 min head-up tilt (HUT) at 60 deg, 10 min combined HUT and lower body suction (LBNP) at -20 mmHg followed by LBNP at -40 mmHg. Pre-syncope was defined as a fall in BP to below 80 mmHg systolic accompanied by symptoms. Baseline supine values were: MAP (means +/- S.E.M.) 84.9 +/- 3.2 mmHg; HR, 63.9 +/- 3.2 beats min-1; CVT, 10.8 +/- 2.6 (arbitrary units) and CSB, 8.2 +/- 1.6 ms mmHg-1. HUT alone provoked pre-syncope in 30 % of the patients whilst the remaining 70 % required LBNP. The cardiovascular responses leading to pre-syncope can be described in four phases. Phase 1, full compensation: where VR increased by 70.9 +/- 0.9 %, MAP was 89.2 +/- 3.8 mmHg and HR was 74.8 +/- 3.2 beats min-1 but CVT decreased to 3.5 +/- 0.5 units and CSB to 2.7 +/- 0.4 ms mmHg-1. Phase 2, tachycardia: a progressive increase in heart rate peaking at 104.2 +/- 5.1 beats min-1. Phase 3, instability: characterised by oscillations in BP and also often in HR; CVT and CSB also decreased to their lowest levels. Phase 4, pre-syncope: characterised by sudden decreases in arterial blood pressure and heart rate associated with intensification of the symptoms of pre-syncope. This study has given a clearer picture of the cardiovascular events leading up to pre-syncope. However, the mechanisms behind what causes a fully compensated system suddenly to become unstable remain unknown.
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Affiliation(s)
- P O O Julu
- Institute for Cardiovascular Research, University of Leeds, UK.
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