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edriscoll
Postural Orthostatic Tachycardia Syndrome (POTS), Dysautonomia, and the Autonomic Nervous System
What is postural orthostatic tachycardia syndrome (POTS)? What are its signs and symptoms and what are the mechanisms by which all body systems are affected? How does the autonomic nervous system normally function? What is the etiology, or cause, of dysautonomia? How is it diagnosed? Can it be treated? Join professor Carrie on a journey through the autonomic nervous system and develop a deeper understanding of autonomic function in general, and POTS in particular. This lecture is presented at the college level and is meant to be accessible for patients, family members, students, and medical professionals. 
0:00 Background and purpose
1:28 Definition and basic mechanism of POTS
8:10 POTS symptoms and causes: acute cerebral hypoperfusion, chronic cerebral hypoperfusion, chronic organ and tissue hypoperfusion, autonomic dysregulation, sympathetic hyperactivity (hyperadrenergic POTS)
16:59 Organization of the nervous system: central nervous system, peripheral nervous system, afferent pathways, efferent pathways, autonomic nervous system, sympathetic division, parasympathetic division
24:23 Nervous system signaling pathways: preganglionic neuron, ganglionic neuron, acetylcholine, cholinergic receptors, nicotinic receptors, muscarinic receptors, norepinephrine, adrenergic receptors, alpha receptors, beta receptors
43:50 The dysautonomia family of conditions: POTS, neurally mediated syncope, autonomic failure
46:13 Etiology of POTS: genetic mutations, joint hypermobility, Ehlers-Danlos syndrome, norepinephrine transporter (NET) deficiency, catecholamine synthesis, tyrosine hydroxylase (TH), aromatic L-amino acid decarboxylase (AADC), dopamine beta-hydroxylase (DBH), catechol-O-methyltransferase (COMT), monoamine oxidase A (MAO-A), epigenetics, deconditioning, mononucleosis, autoimmunity, Guillain-Barre syndrome
1:06:39 Diagnosing POTS: medical history, tilt table test, catecholamines test, specialized autonomic testing
1:16:18 POTS prognosis
1:19:26 Managing and treating POTS -- non-pharmacologic: diet, methylcobalamin, methyltetrahydrofolate, exercise, environment, psychosocial considerations
1:37:47 Managing and treating POTS -- medications: mineralocorticoids, beta-blockers, alpha-agonists, reuptake inhibitors, psychostimulants
1:53:46 Conclusion and hope for the future
edriscoll

POTS What To Avoid

By edriscoll, in POTS,

Ablation of the sinus node may be detrimental to POTS patients. A Mayo Clinic study reported short-term success in five of seven ablated patients with inappropriate sinus tachycardia and postural orthostatic tachycardia features (Shen, Low, Jahangir, Munger, Friedman, Osborn, Stanton, Packer, Rea & Hammill, 2001). However, long-term outcomes were disappointing in these patients. None of the patients experienced complete eradication of symptoms. A follow-up evaluation showed no vast improvement in symptoms, despite better heart rate control. A later publication states "in our laboratory, sinus node modification, total sinus node ablation, or atrioventricular nodal ablation is not recommended for patients with inappropriate sinus tachycardia who have autonomic evidence of postural orthostatic tachycardia" (Shen, 2002).
Ablations have reportedly been detrimental to some POTS patients who were misdiagnosed as having inappropriate sinus tachycardia. After the apparently successful elimination of their "sinus tachycardia", they were left with profound orthostatic hypotension (Grubb & Karas, 1999).
Alcohol enhances peripheral venous pooling, which will exacerbate hypotension (Grubb & Karas, 1999). Alcohol can also lead to a dehydrated state.
Anesthesia can be especially challenging for patients with autonomic dysfunction. When anesthesia is absolutely necessary, an arterial line should be inserted to monitor beat to beat variations in blood pressure. Heart rate should also be constantly monitored, as anesthesia can disturb cardiovascular function. Extra IV fluids are also needed. Read more
Bending up and down, as done when picking items up off of the floor, may increase symptoms. It is best to bend at the knee and squat down rather then to bend over forward at the waist.
Blowing up balloons is similar to the valsalva maneuver and can exacerbate symptoms in some patients.  
Certain Foods, such as dairy products,may increase symptoms in some patients. White sugar and other refined carbohydrates can exacerbate hypotension by causing increased dilation in the gut (Mathias, 2000). It is important to identify and avoid food triggers. Studies show that gluten sensitivity may play a role in neurological disorders (Hadjivassiliou, Gibson, Davies-Jones, Lobo, Stephenson & Milford-Ward, 1996).

Climbing stairs will make some patients feel worse. 
Dehydration is one of the worst states a POTS patient can be in. It is very important to always stay well hydrated.
Doctors who don't know much about POTS will surely leave patients feeling frustrated. Patients of inexperienced doctors may not receive expert care and may not return to optimum health. Finding an experienced physician is not only desirable, it is a necessity. Physicians who treat dysautonomia can be located on our Physician List.
Eating large meals can worsen hypotension in some individuals with dysautonomia (Mathias, 2000). This is because large meals can cause blood to pool excessively in the abdomen.
Energy Drinks, such as Red Bull, should be avoided in those with POTS. Postural tachycardia syndrome associated with a vasovagal reaction was recorded in a young volleyball player after an excess intake of Red Bull as a refreshing energy drink (Terlizzi, Rocchi, Serra, Solieri & Cortelli, 2008).
Epinephrine is used by doctors and dentists for a variety of reasons. It is commonly used in numbing shots. It is wise to avoid epinephrine as it stimulates the heart.
Exercise will make many people with dysautonomia feel worse. Strenuous, exhausting exercise should be avoided. Some patients will experience an exacerbation of symptoms after exercise that may last for a day or more, especially if they suffer from mitochondrial disease. These patients should check with a physician before starting any exercise program.
Exercise may be helpful in abating blood from pooling in the limbs. Exercise to build and strengthen the leg muscles can be especially beneficial. Exercise can help POTS patients to avoid becoming deconditioned. A deconditioned state further exacerbates symptoms of orthostatic intolerance.
Fatigue enhances peripheral venous pooling (Grubb & Karas, 1999). Those with POTS will do well to live life at their own pace. It is important that patients don't overdo it, as this will make them feel even worse. POTS will require some lifestyle modification.
Giving blood can be harmful to people with POTS. Blood pooling in the legs already diminishes the amount of blood flowing to the heart and brain. Further, some patients are hypovolemic (have low blood volume) and need every drop of blood that they have. Blood should not be donated and should only be drawn when necessary for medical reasons. 
Heat dilates blood vessels and will make POTS symptoms worse. Patients should avoid spending a lot of time outdoors on hot days. POTS patients should not take hot showers/baths or subject their bodies to saunas, hot tubs or greenhouses. Heat enhances peripheral venous pooling (Grubb & Karas, 1999).
Holding the arms up in the air can cause problems for some individuals. Holding the arms up requires the heart to work harder to counteract the effects of gravity. This is especially difficult for the heart if there is already excessive venous pooling in the lower limbs. The heart may not be able to effectively pump blood up into raised arms and tachycardia will result from its effort.
Lifting objects can aggravate the symptoms of POTS. This may be due to the increased work load on the heart, especially if blood is pooling in the legs. Pooling blood in the lower body makes less blood available for the muscles in the upper body. Also, straining, bending over, coughing and sneezing all raise cerebral spinal fluid pressure. It has been theorized that some POTS patients may experience symptoms while lifting due to changes in cerebral spinal fluid pressure. 
Many medications will affect autonomic testing results. Some medications that have been reported to significantly affect autonomic testing results include: chlorpromazine, thioridazine, tricyclic antidepressants, bupropion, mirtazepine, vanlafaxine, clonidine, alpha blockers, beta blockers, calcium channel blockers, opiates and topical capsaicin (Sandroni, 1998). Some physicians believe patients should discontinue measures at alleviating symptoms before autonomic testing. By doing so, symptoms are more likely to present during testing. This may help a physician to discern the true nature of a patient's disorder. 
Numerous over-the-counter products, such as melatonin, can negatively effect the POTS patient. Many products stimulate the heart or lower blood pressure or have diuretic effects, etc. Some products can help one person while hindering another. For example, caffeine can have the positive effect of raising blood pressure in some individuals. However, caffeine also increases the length of time that catecholamines remain active and this can be detrimental to those with a hyperadrenergic state. POTS patients should check with their doctor before taking over-the-counter products.
Over-stimulating environments can make POTS symptoms worse. A number of POTS patients report being overly sensitive to bright lights, loud noises and busy environments.
Singing has been reported to temporarily worsen symptoms in some individuals.
Some pharmacologic agents may cause or worsen orthostatic intolerance. Please check with your physician before taking prescription or over-the-counter medications.Some of themedications that physicians have identified as causing or worsening orthostatic intolerance include:
Angiotensin Converting Enzyme Inhibitors (Grubb & Karas, 1999)
Alpha Receptor Blockers (Grubb & Karas, 1999)
Calcium Channel Blockers (Grubb & Karas, 1999)
Beta Blockers (Grubb & Karas, 1999)
Phenothiazines (Grubb & Karas, 1999)
Tricyclic Antidepressants (Grubb & Karas, 1999)
Bromocriptine (Grubb & Karas, 1999)
Ethanol (Grubb & Karas, 1999)
Opiates (Grubb & Karas, 1999)
Diuretics (Grubb & Karas, 1999)
Hydralazine (Grubb & Karas, 1999)
Ganglionic Blocking Agents (Grubb & Karas, 1999)
Nitrates (Grubb & Karas, 1999)
Sildenafil Citrate (Grubb & Karas, 1999)
MAO Inhibitors (Grubb & Karas, 1999)
Olanzapine
Stress will often aggravate the symptoms of POTS. The body is continuously adapting to stress, whether it is physical, mental or chemical. POTS patients sometimes lack the ability to correctly process stress due to malfunctioning or excessive functioning of the autonomic nervous system (ANS). Patients may also already have high levels of norepinephrine, which is a stress hormone. POTS patients need to avoid stress (when possible) and live life at their own pace.      
Specific stresses such as surgery, childbirth and trauma (such as a car accident) have preceded or worsened the development of POTS in some individuals. This is thought to occur due to a number of factors. Surgery, childbirth and trauma can result in excessive blood loss in POTS patients who may already be hypovolemic. It is important for POTS patients to be given extra fluids during these times. Some people theorize that surgery may require a positioning of the neck that can aggravate hind brain compression. While the relationship between hind brain compression and POTS is controversial, it may be wise to avoid these positions (if possible) with POTS patients. Trauma to the neck may also aggravate hind brain compression. Trauma can result in damage to the ANS and also to areas that will secondarily effect the ANS. Likewise, some believe the straining of bearing down during childbirth can aggravate hind brain compression and effect the ANS. POTS occurring as a result of the nutcracker phenomenon is also more prevalent after childbirth. Hormonal shifts have been theorized to contribute to the development or worsening of POTS symptoms after childbirth as well.
Travel by airplane is challenging for dysautonomics and may increase symptoms. Airplane cabins are pressurized to about 6,500 feet, which is high enough to cause some dysautonomia patients to hyperventilate. Hyperventilating makes a patient more likely to get symptoms of sympathetic activation (Robertson, 2002).
Those with POTS do need to know that the air in an airplane is some of the driest in the world. Flying can have dehydrating effects in normal individuals. How much more so flying might dehydrate someone with low blood volume. Everyone should be well hydrated before boarding a plane. Also, normal people sometimes have trouble with blood pooling in their legs during flights. Rarely, this can lead to the development of blood clots. Patients prone to pooling blood may want to wear compression stockings when flying. Patients may also want to request a bulkhead seat, as this will give them more room to elevate their legs. 


References
    1. Grubb, B. P. (2002, October). The heterogeneity of symptoms related to    dysautonomia. Symposium conducted at the meeting of the   National Dysautonomia Research Foundation Northwest Ohio   Support Group. Toledo, Ohio.     2. Grubb, B. P., & Karas, B. (1999). Clinical disorders of the autonomic   nervous system associated with orthostatic intolerance: an overview of   classification, clinical evaluation, and management. Pacing and Clinical   Electrophysiology, 22, 798-810. Full text:   http://www.ndrf.org/PDF%20Files/disorders.PDF     3. Hadjivassiliou, M., Gibson, A., Davies-Jones, G. A., Lobo,  A.J.,   Stephenson, T.J., & Milford-Ward, A. (1996). Does cryptic gluten     sensitivity play a part in neurological illness? Lancet, 10, 369-371.   PMID: 8598704 [PubMed - indexed for MEDLINE]     4. Mathias, C. J. (2000, July). Other autonomic disorders. National Dysautonomia   Research Foundation Patient conference. Minneapolis, Minnesota.     5. Robertson, D. (2002, July). Drug Therapy. National Dysautonomia   Research Foundation Patient conference. Washington, DC.     6. Sandroni, P. (1998, November/December). Testing the autonomic nervous     system. In C. B. Berde, & M. C. Rowbotham (Eds.) International    Association for the Study of Pain: Technical Corner From IASP    Newsletter. Full Text     7. Shen, W. K. (2002). Modification and ablation for inappropriate sinus   tachycardia: current status. Cardiac Electrophysiology Review.   6(4), 349-355. PubMed     8. Shen, W. K., Low, P.A., Jahangir, A., Munger, T. M., Friedman, P. A.,   Osborn, M. J., Stanton, M. S., Packer, D. L., Rea, R. F., Hammill, S. C.   (2001).  Is sinus node modification appropriate for inappropriate sinus   tachycardia with features of postural orthostatic tachycardia syndrome?   Pacing & Clinical Electrophysiology, 24(2), 217-230. PubMed     9. Terlizzi, R., Rocchi, C., Serra, M., Solieri, L., Cortelli, P. (2008). Reversible postural   tachycardia syndrome due to inadvertent overuse of Red Bull.   Clinical Autonomic Research, 18(4), 221-223. PubMed
edriscoll
Anaesthesia
Postural orthostatic tachycardia syndrome: anesthetic implications in the obstetric patient:
http://www.ncbi.nlm.nih.gov/pubmed/17179264?dopt=AbstractPlus

Anaesthetic management of a parturient with the postural orthostatic tachycardia syndrome: a case report:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=16698864&query_hl=1&itool=pubmed_docsum
Preoperative considerations in a patient with orthostatic intolerance syndrome:
http://journals.lww.com/anesthesiology/pages/articleviewer.aspx?year=2000&issue=08000&article=00041&type=fulltext
Autonomic dysfunction - anaesthetic management
http://www.anaesthetist.com/anaes/patient/ans.htm
Baroreflex
Abnormal baroreflex responses in patients with idiopathic orthostatic intolerance:
http://www.ncf-net.org/library/freeman-OI-2000.htm
Baroreflex control of muscle sympathetic nerve activity in postural orthostatic tachycardia syndrome:
http://ajpheart.physiology.org/cgi/content/full/289/3/H1226 
Catecholamines
The broader view: catecholamine abnormalities:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=12102462&dopt=Abstract
Endothelial NO Synthase Polymorphisms and Postural Tachycardia Syndrome:
http://pt.wkhealth.com/pt/re/dyslipidaemia/pdfhandler.00004268-200511000-00008.pdf;jsessionid=LnhQwG11yV0fKLVmTywMzWdZLQfyhxRq1HLnJ9
1n7vhQ2rxnX4yv!-2048123402!181195628!8091!-1
Chiari malformation/spinal cord involvement
Watch a presentation by physicians at The Chiari Institute and NIH as they discuss the possible connection between POTS, Ehlers-Danlos syndrome and Chiari Malformation: (click on the Ehlers-Danlos National Foundation link)
http://www.thechiariinstitute.com/
Cerebral syncope in a patient with spinal cord injury:
http://www.ncbi.nlm.nih.gov/pubmed/11990670?dopt=Abstract

Chiari Malformation:
http://www.dizziness-and-balance.com/disorders/central/cerebellar/chiari.html
Chiari, fibromyalgia, gastrointestinal problems, gulf war syndrome, multiple chemical sensitivities/environmental illness, orthostatic intolerance:
http://www.cfids.org/about-cfids/orthostatic-intolerance.asp
Sinus arrhythmia and pupil size in Chiari I malformation: evidence of autonomic dysfunction:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=8314116&dopt=Abstract
The Chiari Institute:
http://www.chiariinstitute.com/chiari_malformation.html
Autonomic nervous system disorders in 230 cases of basilar impression and arnold-chiari deformity:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1494411&dopt=Abstract
Chiari I malformation as a cause of orthostatic intolerance symptoms: a media myth?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=11705431&dopt=Abstract
No increased herniation of the cerebellar tonsils in a group of patients with orthostatic intolerance:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12598952&dopt=Abstract
Orthostatic intolerance and syncope associated with Chiari type I malformation:
http://jnnp.bmj.com/cgi/content/full/76/7/1034
Orthostatic hypotension following spinal cord injury: understanding clinical pathophysiology:
http://www.nature.com/sc/journal/v44/n6/full/3101855a.html
Chronic fatigue syndrome
The importance of orthostatic intolerance in the chronic fatigue syndrome:
http://www.ncf-net.org/library/orthostaticreview.htm
MEDLINEplus health information on chronic fatigue syndrome:
http://www.nlm.nih.gov/medlineplus/chronicfatiguesyndrome.html
Chronic fatigue syndrome: A hypothesis focusing on the autonomic nervous system:
http://cs.portlandpress.com/cs/096/0117/0960117.pdf
Dental Considerations
Postural Orthostatic Tachycardia Syndrome: Dental Treatment Considerations by John K. Brooks, DDS; Laurie A. P. Francis, RDH: 
http://jada.ada.org/cgi/reprint/137/4/488.pdf
Diabetes and autonomic neuropathy
Chronic administration of pharmacologic doses of vitamin E improves the cardiac autonomic nervous system in patients with type 2 diabetes:
http://www.ajcn.org/cgi/content/full/73/6/1052
Value of scintigraphy using meta-iodo-benzyl-guanidine (MIBG) in the investigation of cardiac autonomic neuropathy in diabetic patients. Comparison with Ewing tests:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9404408&dopt=Abstract
Abnormal cardiovascular reflexes in juvenile diabetics as preclinical signs of autonomic neuropathy:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7346309&dopt=Abstract
Response of the autonomous nervous system of the heart in diabetes mellitus:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=529862&dopt=Abstract
MEDLINEplus health information on diabetes:
http://www.nlm.nih.gov/medlineplus/diabetes.html
Disability
Blood volume perturbations in the postural tachycardia syndrome:
PubMed

Quality of life in patients with postural tachycardia syndrome:
http://www.ncbi.nlm.nih.gov/pubmed/12059122 
Ehlers-Danlos Syndrome (Joint Hypermobility Syndrome)
Ehlers Danlos Syndrome. University of Washington, Seattle:
http://www.orthop.washington.edu/uw/ehlersdanlos/tabID__3376/ItemID__32/PageID__1/Articles/Default.aspx
Ehlers-Danlos National Foundation:
http://www.ednf.org/
Ehlers-Danlos syndrome, classical type:
http://ghr.nlm.nih.gov/condition=ehlersdanlossyndromeclassicaltype 
Ehlers-Danlos syndrome, hypermobility type:
http://ghr.nlm.nih.gov/condition=ehlersdanlossyndromehypermobilitytype
Joint hypermobility syndrome: a complex constellation of symptoms:
http://www.reumatologia-dr-bravo.cl/para%20medicos/HIPERLAXITUD/
www_jointandbone_org_RODGRAH.htm
Connective tissue disorders with spontaneous spinal cerebrospinal fluid leaks and intracranial 
hypotension: a prospective study:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=14683542&dopt=Abstract
Association Between Joint Hypermobility Syndrome and Panic Disorder:
http://ajp.psychiatryonline.org/cgi/content/full/155/11/1578
Is joint hypermobility related to anxiety in a nonclinical population also?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15345789
Neurological manifestations of Ehlers-Danlos syndrome:
http://www.neurologyindia.com/article.asp?issn=0028-3886;year=2005;volume=53;issue=3;spage=339;epage=341;aulast=Mathew
Your eyes and Ehlers-Danlos Syndrome:
http://www.totaleyecare.com/ocular-complication-ehlers-danlos-syndrome-1.html?_ga=1.14621751.1418931888.1390611040
Exercise
The prevalence and significance of post-exercise (postural) hypotension in ultramarathon runners:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8614313&dopt=Abstract
Fainting
Certain cardiovascular indices predict syncope in the postural tachycardia syndrome:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8902319&dopt=Abstract
Fibromyalgia
National Fibromyalgia Research Association:
http://www.nfra.net/
MEDLINEplus health information on fibromyalgia:
http://www.nlm.nih.gov/medlineplus/fibromyalgia.html
Elusive syndromes: Treating the biologic basis of fibromyalgia and related syndromes:
http://www.ccjm.org/pdffiles/Clauw1001.pdf
Hormones
Influence of the menstrual cycle on sympathetic activity, baroreflex sensitivity, and vascular
transduction in young women:
http://circ.ahajournals.org/cgi/content/full/101/8/862
Hypovolemia
Hypovolemia in syncope and orthostatic intolerance role of the renin-angiotensin system:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9274896&dopt=Abstract
Is this patient hypovolemic?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10086438&dopt=Abstract
Idiopathic hypovolemia: a self perpetuating autonomic dysfunction?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9869552&dopt=Abstract
Lipodystrophy
Partial lipodystrophy in a boy:
http://www.indianpediatrics.net/jan2000/case3.htm
Magnesium
Erythrocyte magnesium in symptomatic patients with primary mitral valve prolapse: relationship to symptoms, mitral leaflet thickness, joint hypermobility and autonomic regulation:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1844553&dopt=Abstract
Cardiovascular consequences of magnesium deficiency and loss: pathogenesis, prevalence and manifestations. Magnesium and chloride loss in refractory potassium repletion:
http://www.mgwater.com/cardio.shtml
Magnesium and therapeutics:
http://www.mgwater.com/dur01.shtml
Magnesium deficiency in the pathogenesis of mitral valve prolapse:
http://www.mdheal.org/magnesiu.htm
Review and hypothesis: Might patients with the chronic fatigue syndrome have latent tetany 
of magnesium deficiency:
http://www.mgwater.com/clmd.shtml
The magnesium web site - Links to over 300 articles discussing magnesium and magnesium 
deficiency:
http://www.mgwater.com/index.shtml

Medications/Treatments
Web Site for Cardiovascular and Autonomic Pharmacology:
http://courses.washington.edu/chat543/cvans/
Drug protects against nervous system failure:
http://www.news.harvard.edu/gazette/1997/04.17/DrugProtectsAga.html

Treatment of orthostatic hypotension with erythropoietin:
http://content.nejm.org/cgi/content/absract/329/9/611

Effects of long-term clonidine administration on the hemodynamic and neuroendocrine postural 
responses of patients with dysautonomia:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=6295714&dopt=Abstract
Cardiac vagal response to water ingestion in normal human subjects:
http://cs.portlandpress.com/cs/103/0157/cs1030157.htm
Medicinal uses of licorice through the millennia: the good and plenty of it:
http://fkogserver.bmc.uu.se/course/B/Liquorice.pdf
Licorice root. A natural sweetener and an important ingredient in Chinese medicine:
http://www.iupac.org/publications/pac/2002/pdf/7407x1189.pdf
Licking latency with licorice root:
http://www.jci.org/cgi/content/full/115/3/591
Adverse drug reactions related to drugs used in orthostatic hypotension: a prospective and systematic pharmacovigilance study in France:
http://www.ncbi.nlm.nih.gov/pubmed/15991040?dopt=Abstract
Mitochondrial disease and dysautonomia
Mitochondrial cytopathy in adults: what we know so far:
http://www.ccjm.org/pdffiles/COHEN701.PDF

Mitochondrial encephalomyopathies presenting with features of autonomic and visceral dysfunction:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=8736411&dopt=Abstract
A case of mitochondrial encephalomyopathy with peripheral neuropathy and autonomic symptoms:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=7605684&dopt=Abstract
Neurologic presentations of mitochondrial disorders
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10641610&dopt=Abstract
Mitral valve prolapse
The phenomenon of dysautonomia and mitral valve prolapse:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=8003350&dopt=Abstract
Exercise response in young women with mitral valve prolapse:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=2805839&dopt=Abstract
Multiple system atrophy/shy-drager syndrome
SDS/MSA support group:
http://www.shy-drager.org/
Web site full of links to other sites about MSA/SDS:
 http://www.corwin-millman.com/shy-drager/links.html

Norepinephrine transporter
Genetic or acquired deficits in the norepinephrine transporter: current understanding of clinical 
implications:
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=168695
Orthostatic intolerance is not necessarily related to a specific mutation (Ala457Pro) in the human norepinephrine transporter gene:
http://www.ncbi.nlm.nih.gov/pubmed/12589229?dopt=Abstract

Phenotypical evidence for a gender difference in cardiac norepinephrine transporter function: 
http://ajpregu.physiology.org/cgi/content/full/286/5/R851
The Nutcracker phenomenon
Does severe nutcracker phenomenon cause pediatric chronic fatigue?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10749295&dopt=Abstract
Nutcracker phenomenon demonstrated by three-dimensional computed tomography:
http://www.medonline.com.br/nutpn.pdf
Diagnosis of the nutcracker phenomenon using two-dimensional ultrasonography:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=9491284&dopt=Abstract
Magnetic resonance angiography in nutcracker phenomenon:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10230562&dopt=Abstract
An effective "transluminal balloon angioplasty" for pediatric chronic fatigue syndrome with nutcracker phenomenon:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10661488&dopt=Abstract
Nutcracker phenomenon treated with left renal vein transposition: a case report:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10331171&dopt=Abstract
The nutcracker syndrome: its role in the pelvic venous disorders:
http://www.ncbi.nlm.nih.gov/pubmed/11700480?dopt=Abstract
Outlook
Orthostatic hypotension in organic dementia: relationship between blood pressure, cortical blood flow and symptoms:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=8924753&dopt=Abstract
Neurocardiovascular instability, hypotensive episodes, and MRI lesions in neurodegenerative dementia:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10818535&dopt=Abstract
Orthostatic hypotension in Alzheimer's disease: result or cause of brain dysfunction?
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=10476310&dopt=Abstract
Orthostatic hypotension as a risk factor for stroke:
http://stroke.ahajournals.org/cgi/pmidlookup?view=full&pmid=11022055
Orthostatic hypotension
Orthostatic hypotension:
http://www.dizziness-and-balance.com/disorders/medical/orthostatic.html
Cardiovascular Causes of Falls by Brian J. Carey and John F. Potter:
http://ageing.oxfordjournals.org/cgi/reprint/30/suppl_4/19.pdf
Orthostatic Hypotension by Bradley JG, Davis KA.
http://www.aafp.org/afp/20031215/2393.pdf
Paraneoplastic syndromes
Immunological and endocrinological abnormalities in paraneoplastic disorders with involvement of the autonomic nervous system:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=9241563&dopt=Abstract
Pheochromocytoma
Biochemical diagnosis of pheochromocytoma:
http://www.angelfire.com/hi/Pheochromocytoma/biodiag.html
MEDLINEplus health information on pheochromocytoma:
http://www.nlm.nih.gov/medlineplus/pheochromocytoma.html
Germ-line mutations in nonsyndromic pheochromocytoma:
http://content.nejm.org/cgi/content/abstract/346/19/1459
Porphyria
Diagnosis and management of porphyria:
http://bmj.bmjjournals.com/cgi/content/full/320/7250/1647
Postural orthostatic tachycardia syndrome/orthostatic intolerance
Medscape: Postural Tachycardia Syndrome:
http://www.medscape.com/viewarticle/705183
The Postural Tachycardia Syndrome (POTS): Pathophysiology, Diagnosis & Management
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1501099/
Orthostatic intolerance:
http://www.nymc.edu/fhp/centers/syncope/chronic_orthostatic_intolerance.htm
A review of the classification, diagnosis, and management of autonomic dysfunction syndromes associated with orthostatic intolerance:
http://publicacoes.cardiol.br/abc/2000/7406/74060008i.pdf
Clinical disorders of the autonomic nervous system associated with orthostatic intolerance: an overview of classification, clinical evaluation and management:
http://www.ndrf.org/PDF%20Files/disorders.PDF
The neuropathic postural tachycardia syndrome:
http://content.nejm.org/cgi/content/abstract/343/14/1008
Hereditary dysautonomias: Current knowledge and collaborations for the future:
Oct 3, 2002 http://www.familialdysautonomia.org/NIH_OCT3.pdf 
Oct. 4 2002 http://www.familialdysautonomia.org/NIH_OCT4.pdf
Effects of head-up tilting on baroreceptor control in subjects with different tolerances to orthostatic stress:
http://cs.portlandpress.com/cs/103/0221/cs1030221.htm
Vascular perturbations in the chronic orthostatic intolerance of the postural orthostatic tachycardia syndrome:
http://jap.physiology.org/cgi/content/full/89/4/1505
American Autonomic Society: (be sure to visit the autonomic news section for information on the latest research)
www.americanautonomicsociety.org/
Postural tachycardia syndrome and anxiety disorders:
http://jnnp.bmj.com/content/80/3/339.abstract/reply#jnnp_el_4620
Pregnancy
Postpartum Postural Orthostatic Tachycardia Syndrome in a Patient with the Joint Hypermobility Syndrome:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2778448/
Postural orthostatic tachycardia syndrome: anesthetic implications in the obstetric patient:
http://www.ncbi.nlm.nih.gov/pubmed/17179264?dopt=%20AbstractPlus
Research Studies
ClinicalTrials.gov
http://www.clinicaltrials.gov/
DINET studies page:
http://dinet.org/index.php/information-resources/studies
NDRF clinical research page:
http://www.ndrf.org/dysautonomia_clinic_resea.htm
Support
12 More Pages:
http://www.12morepages.com
STARS US (Syncope Trust and Reflex Anoxic Seizures)
http://www.stars-us.org/
STARS - syncope trust and reflex anoxic seizures:
www.stars.org.uk
National Dysautonomia Research Foundation:
www.ndrf.org
Dysautonomia Youth Network of America (DYNA) (devoted to youth with dysautonomia)
http://www.dynainc.org/
Syringomyelia
NINDS syringomyelia information page:
http://www.ninds.nih.gov/health_and_medical/
disorders/syringomyelia_short.htm
Postural tachycardia syndrome in syringomyelia: response to fludrocortisone and beta-blockers:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=11710800&dopt=Abstract
Involvement of the autonomic nervous system in patients with syringomyelia - a study with the sympathetic skin response:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=8654321&dopt=Abstract
Hyperhidrosis as the presenting symptom in post-traumatic syringomyelgia: (hyperhidrosis is excessive sweating)
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=8090551&dopt=Abstract
Cardiovascular reflexes in syringomyelia:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=
Retrieve&db=PubMed&list_uids=7139257&dopt=Abstract
MEDLINEplus health information on syringomyelia:
http://www.nlm.nih.gov/medlineplus/syringomyelia.html
Tests
The fainting patient: value of the head-upright tilt-table test in adult patients with orthostatic intolerance:
http://www.cmaj.ca/cgi/content/full/164/3/372
Autonomic diseases: clinical features and laboratory evaluation:
http://jnnp.bmjjournals.com/cgi/content/full/74/suppl_3/iii31
Syncope Care & Treatment:
http://my.clevelandclinic.org/heart/disorders/electric/syncope.aspx
Videos 
The Dysautonomia Information Network presents the first full length documentary about Postural Orthostatic Tachycardia Syndrome.
http://dinet.org/index.php/information-resources/pots-place/pots-video
POTS - Mayo Clinic:
http://www.youtube.com/watch?v=CatWlEGPqG4&feature=related
POTS syndrome - Mayo Clinic:
http://www.youtube.com/watch?v=iJ9bv7jx-Ls&feature=channel
The Woman who Kept Falling Down - Mystery Diagnosis - Part 1:
http://www.youtube.com/watch?v=NN3PB6N6oGY

The Woman who Kept Falling Down - Mystery Diagnosis - Part 2:
http://www.youtube.com/watch?v=I40-r3RpFjs&NR=1 

The Woman who Kept Falling Down - Mystery Diagnosis - Part 3:
http://www.youtube.com/watch?v=PHydjGdg4XQ&NR=1
edriscoll
What is Neurocardiogenic Syncope?
Neurocardiogenic syncope is a temporary loss of consciousness associated with a drop in arterial blood pressure, quickly followed by a slowed heart rate (Grubb & McMann, 2001, p. 133).
Neurocardiogenic syncope (NCS) is also referred to as vasovagal syncope or neurally mediated syncope. The terms are used interchangeably throughout this web page. 

What are the symptoms of NCS?
Neurocardiogenic fainting usually occurs while standing. Emotional stress, stressful condition and pain may trigger an episode, especially among the young (Shah, Gupta & Lokhandwala, 2003). The onset may be abrupt or associated with warning symptoms such as fatigue, weakness, nausea, sweating, pallor, visual disturbances, abdominal discomfort, headache, pins-and-needles, lightheadedness or vertigo (Deering, 2003). Presyncopal patients may also complain of palpitations, vomiting, disorientation, and difficulty speaking clearly or coherently (Grubb & McMann, 2001, p. 60.). Other symptoms that may present before a faint include feeling either warm or cold, tremors, yawning and having a bluish/purple or red coloring to the skin (Alboni, Brignole, Menozzi, Raviele, Del Rosso, Dinelli, Solano & Bottoni, 2001).
During the faint "seizure-like" activity may occur (Grubb, Gerard & Roush, 1991). This convulsive activity is thought to be distinct from a seizure disorder.
Patients are sometimes symptomatic after a faint as well. Patients may complain of symptoms including nausea, clamminess, lightheadedness, headache and malaise (Deering, 2003). Patients may also experience vomiting, abdominal discomfort, weakness, tremors, cold or warm feelings and confusion (Alboni et al., 2001). Patients who experience frequent neurocardiogenic syncope may report symptoms between faints as well, such as chronic fatigue, headache, chest pain, exercise intolerance, heart "flip flops" and an inability to tolerate prolonged standing.
Mechanisms and Causes of NCS
When a person stands up, the pull of gravity causes blood to pool in the lower extremities. This can result in a lack of blood supply to the upper body, including the heart and brain. Normally, the body automatically adjusts to the lack of blood supply by increasing vascular tone, heart rate and cardiac output. Blood vessels contract, heart rate increases, systolic blood pressure remains about the same or drops slightly while diastolic pressure rises slightly (Brunner & Suddarth, 2000, p. 546).
In those with neurocardiogenic syncope this compensatory mechanism does not always work correctly. The exact mechanisms of NCS are not completely understood, and several theories have been proposed. Many physicians hold a general consensus as to what is happening during NCS as follows:
The strong contractions of the ventricle walls are thought to cause a response in the mechanoreceptors, which misinterpret what is happening and send a message to the brain that the blood pressure is actually high. In response, the sympathetic portion of the cardiovascular center reduces its impulses to the heart and blood vessels while the parasympathetic division increases its impulses (Grubb & McMann, 2001, p. 61-62). This abnormal nervous system reflex causes the heart to slow and the blood vessels to dilate (open up), further lowering blood pressure (North American Society of Pacing and Electrophysiology, 1999). Because of this faulty adjustment, NCS patients may experience intermittent fainting.
A 2004 research publication suggests patients may awaken from sleep with symptoms of forthcoming neurocardiogenic syncope (Krediet, Jardine, Cortelli, Visman & Wieling, 2004). This suggestion may seem to contradict current teachings on this disorder. However, research shows that transient autonomic mechanisms that predispose to vasovagal syncope may occur during sleep (Shneerson, 2000, p. 1-15).
Findings from a 2008 neurocardiogenic syncope study seem to contradict current beliefs regarding what happens during a fainting episode as well. The results did not show an increase in ventricular contractility before tilt-induced syncope, or in presence of a valuable increase of sympathetic activity. Instead, the researchers observed a reduction of atrial contractility, which they believe may be a contributory component in the pathogenesis of vasovagal syncope .
There are several other factors that may be contributory components in the pathogenesis of vasovagal syncope as well.  Differential changes in plasma levels of epinephrine, renin, endothelin, vasopressin, cortisol, prolactin, beta endorphins and substance P have been reported by some investigators either prior to or during a syncopal episode in patients with vasovagal syncope (Ellenbogen, Morillo, Wood, Gilligan, Eckberg & Smith, 1997). Further research has shown that galanin may play a role in one's ability to adapt to orthostatic stress. Patients may have a genetic susceptibility to NCS as well.
Some researchers have suspected that serotonin might be involved in the pathogenesis of NCS. Studies in animals have shown that the withdrawal of sympathetic impulses correlates with a higher level of serotonin being present in the central nervous system, the brain and the spinal cord (Grubb & McMann, 2001, p. 57). However a later study of NCS patients found no differences in serotonin activity at the time of fainting, but did show a lower serotonin level in patients during the early phase of tilt table testing (Mitro, Hijova & Mudrakova, 2006).
Another study showed that young women who had vasovagal syncope with a positive tilt test result had a greater sensitivity to insulin. Insulin, in addition to its known metabolic effects, has sympatho-excitatory and vasodilatory actions on muscular blood vessels. The authors of this study conclude that insulin hypersensitivity could be one of the predisposing factors for vasovagal episodes (Ruiz, Calvar, Hermes, Rivadeneira, Bengolea, Chirife, Tentori & Gelpi, 2003).
How is NCS diagnosed?
Tilt table testing is often used to diagnose NCS. However, tilt table testing can have false-negative and false-positive results (Levine, 1999).
How is NCS treated?
There are a variety of non-pharmacutical methods used to control and prevent neurocardiogenic syncope. No single therapy has been found to be effective in all patients. Non-pharmacutical therapies used to treat NCS include the following:
Cardioneuroablationreportedly has helped some neurocardiogenic syncope patients, although the study reporting this was small and patients had only been followed up for 9 months at the time of publishing (Pachon, Pachon, Pachon, Lobo, Pachon, Vargas & Jatene, 2005). Further investigation is warranted.
Counter-maneuvers may help some patients with neurocardiogenic syncope. Research has shown that physical counterpressure maneuvers are a risk-free, effective, and low-cost treatment for patients with vasovagal syncope and recognizable prodromal symptoms, and should be advised as first-line treatment in these patients (van Dijk, Quartieri, Blanc, Garcia-Civera, Brignole, Moya & Wieling, 2006).
Isometric arm counter-pressure maneuvers can increase systolic blood pressure and prevent fainting in some patients with NCS (Brignole, Croci, Menozzi, Solano, Donateo, Oddone, Puggioni & Lolli, 2002). Patients can perform isometric arm counter-pressure maneuvers by gripping one had with the other and pushing both arms away from their chest.  
Leg crossing combined with muscle tensing at the onset of prodromal symptoms can postpone, and in some instances prevent, vasovagal syncope (Krediet, van Dijk, Linzer, van Lieshout & Wieling, 2002).
Sitting with the head between the knees often is an effective means of preventing syncope (Mathias, 2003).
One patient has reported success in warding off a fainting episode by gently but briskly stepping in place for a short time, bringing the knees a little upward and puffing out the exhale with each rep. Pumping the arms and fists during this counter-maneuver has helped her as well.
Increasing dietary salt and fluid intake may help prevent symptoms associated with neurocardiogenic syncope (Bloomfield, 2002).
Orthostatic self-training and tilt training may help select patients with NCS (Abe, Kondo, Kohshi, Nakashima, 2002). It is of greatest benefit to younger patients and those who faint frequently (Zeng, Ge, Zhang, Wang, & Guo, 2008). Orthostatic self-training involves standing against a wall, without moving, twice a day for a planned duration of up to 30 minutes. The results of orthostatic self-training studies have been mixed, with one study concluding it ineffective in reducing the positive response rate of head-up tilt test in patients with recurrent neurally mediated syncope (On, Park, Huh, & Kim, 2007).

Tilt training involves inclining patients on a tilt table each day. Some patients have to continually be inclined for this therapy to be effective. This therapy will not be effective in all patients. However, one study showed that in 19 patients who abandoned tilt training after about 1 year, none of them reported fainting during daily life. The authors of this study hypothesize that the disturbed autonomic reflex activity may have been restored in these patients (Reybrouck, Heidbuchel, Van De Werf & Ector, 2002).
Paced breathing may help to prevent vasovagal syncope induced by head-up tilt test. Researchers who studied the effects of paced breathing believe respiratory training could be useful in the prevention of vasovagal syncope (Jauregui-Renaud, Marquez, Hermosillo, Sobrino, Lara, Kostine & Cardenas, 2003).

Removal or avoidance of agents that predispose to hypotension or dehydration can lessen the occurance of neurocardiogenic syncope (Bloomfield, 2002). Situations that can predispose an individual to syncope are listed on the POTS Place "What to Avoid" page.
There are a variety of medications and medical treatments that may help prevent neurocardiogenic syncope as well. These include the following:
ACE inhibitors may prevent NCS, presumably through inhibition of sympathetic system activation and the peripheral hypotensive effect (Zeng, Zhu, Liu, Hu, Wang, Yang, Wang, He & Tan, 1998).
Alpha-agonists increase venous tone and decrease pooling, which may prevent activation of mechano-receptors. They also counteract the arteriolar vasodilation produced by the triggering of the vasovagal reflex (Raviele, Themistoclakis & Gasparini, 1996, p. 115). Midodrine is an example of an alpha-agonist that is used to treat NCS. Midodrine has been shown to significantly improve orthostatic tolerance during head-up tilt in patients with recurrent neurally mediated syncope (Kaufmann, Saadia & Voustianiouk, 2002). Researchers have also found Midodrine to be effective in both treating and preventing vasovagal syncope in children (Qingyou, Z., Junbao, D. & Chaoshu, T., 2006). 
Beta blockers have been reported in many studies to be effective in treating neurocardiogenic syncope. Presumably, these agents exert their effects through their negative inotropic actions, which are felt to diminish the degree of cardiac mechano-receptor activation or by acting elsewhere to oppose the high levels of circulating epinephrine (Raviele, Themistoclakis & Gasparini, 1996, p. 114). However, studies of the efficacy of beta blockers in treating NCS have had mixed results. One study showed that propranolol, nadolol and placebo were all equally effective in treating vasovagal syncope (Flevari, Livanis, Theodorakis, Zarvalis, Mesiskli & Kremastinos, 2002). The physicians conducting this study concluded that beta blockers are no better than placebo at reducing neurocardiogenic syncope.
Another study showed nonselective beta blockers to be more effective than beta-1-selective blockers in preventing tilt-induced syncope (Dendi & Goldstein, 2002).
Calcium Channel Blockers may be effective in some patients with NCS. However, in a study comparing verapamil (a calcium channel blocker) to metoprolol (a beta blocker), verapamil was found to be less effective in the management of neurocardiogenic syncope (Jhamb, Singh, Sharda, Kaul, Goel, Talwar & Wasir, 1996).
Disopyramide has negative inotropic and anticholinergic effects that may be potentially beneficial in preventing vasovagal syncope by decreasing ventricular contractibility and counteracting parasympathetic activity (Raviele, Themistoclakis & Gasparini, 1996, p. 114).

Fludrocortisone is sometimes used to prevent neurocardiogenic syncope. There is considerable clinical experience and a consensus suggesting that fludrocortisone is effective (Bloomfield, 2002).
Pacemakers are a somewhat controversial treatment for neurocardiogenic syncope. Many studies have suggested the efficacy of pacemakers. However, a double-blind randomized trial showed that pacing therapy did not reduce the risk of recurrent syncope in patients with vasovagal syncope. The authors of this study concluded that pacemaker therapy should not be recommended as a first-line therapy for patients with recurrent vasovagal syncope (Connolly, Sheldon, Thorpe, Roberts, Ellenbogen, Wilkoff & Morillo, 2003).
Scopolamine may be effective in reducing the high vagal tone that occurs during syncopal episodes (Raviele, Themistoclakis & Gasparini, 1996, p. 115).
Serotonin Reuptake Inhibitors may prevent NCS by reducing the sympathetic impulses that signal the heart to contract more strongly (Grubb & McMann, 2001, p. 115).
Theophylline is an adenosine receptor blocker. It may prevent NCS, although patients sometimes discontinue theophylline because of adverse reactions (Nelson, Stanley, Love, Coyne & Schaal, 1991). Theophylline is not generally used as a first line treatment for NCS.
Patients sometimes need a combination of medications to prevent recurrent neurocardiogenic syncope.
To read more on NCS, please visit our neurocardiogenic syncope links page.
References
    1. Abe, H., Kondo, S., Kohshi, K., Nakashima, Y. (2002). Usefulness of   orthostatic self-training for the prevention of neurocardiogenic syncope.   Pacing & Clinical Electrophysiology, 25(10), 1454-1458. Pubmed     2. Alboni, P., Brignole, M., Menozzi, C., Raviele, A., Del Rosso, A., Dinelli, M.,    Solano, A.,  & Bottoni N. (2001). Diagnostic value of history in patients     with syncope with or without heart disease. Journal of the American    College of Cardiology, 37, 1921-1928. PubMed     3. Bloomfield, D. M. (2002). Strategy for the management of vasovagal syncope.   Drugs & Aging, 19(3), 179-202.     4. Brignole, M., Croci, F., Menozzi, C., Solano, A., Donateo, P., Oddone, D.,   Puggioni, E. &  Lolli, G. (2002). Isometric arm counter-pressure maneuvers   to abort impending vasovagal syncope. Journal of the American College   of Cardiology, 40(11), 2053-2059. PubMed     5. Brunner, L. S. & Suddarth, D. S. (2000). Assessment of cardiovascular   function. In S. C. Smeltzer & B. G. Bare (Eds.), Brunner and Suddarth's   textbook medical-surgical nursing (pp. 532-563). Philadelphia, PA:   Lippincott Williams and Wilkins.     6. Connolly, S. J., Sheldon, R., Thorpe, K. E., Roberts, R. S., Ellenbogen, K. A.,   Wilkoff, B. L.,  Morillo, C., & Gent, M. (2003). Pacemaker therapy   for prevention of syncope in patients with recurrent severe vasovagal   syncope: Second Vasovagal Pacemaker Study (VPS II): a randomized trial.   Journal of the American Medical Association, 289(17), 2224-2229.   PubMed     7. Deering, A. (2003). Cheltenham Syncope Clinic. Retrieved May 15, 2003.   http://www.syncope.co.uk/     8. Dendi, R., & Goldstein, D. S. (2002). Meta-analysis of nonselective versus   beta-1 adrenoceptor- selective blockade in prevention of tilt-induced   neurocardiogenic syncope. American Journal of Cardiology, 89(11),   1319-1321. PubMed     9. Ellenbogen, K. A., Morillo, C. A., Wood, M. A., Gilligan, D. M., Eckberg,   D. L., Smith, M. L. (1997). Neural monitoring of vasovagal syncope.   Pacing & Clinical Electrophysiology. 20(3 Pt 2), 788-794. PubMed     10. Flevari, P., Livanis, E. G., Theodorakis, G. N., Zarvalis, E., Mesiskli, T.,   Kremastinos, D. T. (2002). Vasovagal syncope: a prospective, randomized,   crossover evaluation of the effect of propranolol, nadolol and placebo   on syncope recurrence and patients' well-being. Journal of the American   College of Cardiology, 40(3), 499-504. PubMed     11. Grubb, B. P., Gerard, G., Roush, K. (1991 ). Differentiation of convulsive   syncope and epilepsy with head up tilt table testing. Annals of Internal   Medicine, 117, 871-876. PubMed     12. Grubb, B. P. & McMann, M. C. (2001). The fainting phenomenon:   Understanding why people faint and what can be done about it. New   York: Futura Publishing Company, Inc.     13. Jauregui-Renaud, K., Marquez, M. F., Hermosillo, A. G., Sobrino, A., Lara,   J. L.,  Kostine, A., Cardenas, M. (2003). Paced breathing can prevent   vasovagal syncope during head-up tilt testing. Journal Canadien de   Cardiologie, 19(6), 698-700. PubMed     14. Jhamb,  D. K., Singh, B., Sharda, B., Kaul, U., Goel, P., Talwar, K. K.,   Wasir, H. S. (1996). Comparative study of the efficacy of metoprolol and   verapamil in patients with syncope and positive head-up tilt test response.   American Heart Journal, 132(3), 608-611. PubMed     15. Kaufmann, H., Saadia, D., Voustianiouk, A. (2002). Midodrine in neurally   mediated syncope: a double-blind, randomized, crossover study.   Annals of Neurology, 52(3), 342-345. PubMed     16. Krediet, C. T., van Dijk, N., Linzer, M., van Lieshout, J. J., Wieling, W.   (2002). Management of vasovagal syncope: controlling or aborting faints by   leg crossing and muscle tensing. Circulation, 106(13), 1684-1689.   PubMed     17. Krediet, C. T., Jardine, D. L., Cortelli, P., Visman, A. G., Wieling, W.   (2004). Vasovagal syncope interrupting sleep? Heart, 90(5), e25. PubMed     18. Levine, M. M. (1999). Neurally mediated syncope in children: results of tilt   testing, treatment, and long-term follow-up. Pediatric Cardiology, 20(5),   331-335. PubMed     19. Mathias, C. J. (2003). Autonomic diseases: management. Journal of   Neurology, Neurosurgery & Psychiatry. 74 Suppl 3:iii, 42-47.   Full Text: http://jnnp.bmjjournals.com/cgi/content/full/74/suppl_3/iii42     20. Mitro, P., Hijova E. & Mudrakova K. (2006). Role of the peripheral   serotoninergic system in the pathogenesis of vasovagal syncope.   Bratisl Lek Listy. 107(6-7), 248-52. PubMed     21. Nelson, S. D., Stanley, M., Love, C. J., Coyne, K. S., Schaal, S.F. (1991).   The autonomic and hemodynamic effects of oral theophylline in patients   with vasodepressor syncope.Archives of Internal Medicine, 151(12),   :2425-2429. PubMed     22. North American Society of Pacing and Electrophysiology. (1999). Other   tests: tilt table test. Retrieved June 17, 2003, from NASPE Heart Rhythm   Society. No longer available.     23. On, Y. K., Park, J., Huh, J., & Kim,  J. S. (2007). Is home orthostatic   self-training effective in preventing neurally mediated syncope?   Pacing Clin Electrophysiol. 30(5), 638-643. PubMed     24. Pachon M. J. C., Pachon, M. E. I., Pachon, M. J. C., Lobo, T. J., Pachon,   M. Z., Vargas, R. N. & Jatene, A. D. (2005). "Cardioneuroablation" -   new treatment for neurocardiogenic syncope, functional AV block and   sinus dysfunction using catheter RF-ablation. Europace. 7(1), 1-13.   PubMed     25. Qingyou, Z., Junbao, D. & Chaoshu, T. (2006). The efficacy of midodrine   hydrochloride in the treatment of children with vasovagal syncope.   J Pediatr, 149(6), 777-780. PubMed     26. Raviele, A., Themistoclakis, S. & Gasparini, G. (1996). Drug treatment of   vasovagal syncope. In J. J. Blanc and D. Benditt (Eds.), Neurally   mediated syncope: pathophysiology, investigations, and treatment   (pp. 113-117). Armonk, NY: Futura Publishing Co.     27. Reybrouck, T., Heidbuchel, H., Van De Werf, F., Ector, H. (2002).   Long-term follow-up results of tilt training therapy in patients with recurrent   neurocardiogenic syncope. Pacing & Clinical Electrophysiology, 25(10),   1441-1446. PubMed     28. Ruiz, G. A., Calvar, C., Hermes, R., Rivadeneira, D., Bengolea, V., Chirife,   R., Tentori, M. C., & Gelpi, R. J. (2003). Insulin sensitivity in young   women with vasovagal syncope. American Heart Journal, 145(5),   834-840. PubMed     29. Shah, J. S., Gupta, A. K. & Lokhandwala, Y. Y. (2003). Neurally mediated   syncope: an overview and approach. Journal of the Association of   Physicians of India. 51, 805-810.     30. Shneerson, J. M. (2000). Handbook of sleep medicine. Oxford: Blackwell   Science.     31. van Dijk, N., Quartieri, F., Blanc, J. J., Garcia-Civera, R., Brignole, M.,   Moya, A. & Wieling, W. (2006). Effectiveness of physical counterpressure   maneuvers in preventing vasovagal syncope: the Physical Counterpressure   Manoeuvres Trial (PC-Trial). J Am Coll Cardiol. 48(8), 1652-1657.     32. Zeng, C., Zhu, Z., Liu, G., Hu, W., Wang, X., Yang, C., Wang, H., He, D.,   & Tan, J. (1998). Randomized, double-blind, placebo-controlled trial of oral   enalapril in patients with neurally mediated syncope. American Heart   Jounal, 136(5), 852-858. PubMed     33. Zeng, H., Ge, K., Zhang, W., Wang, G., & Guo, L. (2008) The effect of orthostatic   training in the prevention of vasovagal syncope and its influencing factors.   Int Heart J. 49(6), 707-712.
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