Neurally mediated syncope: pathophysiology and implications for treatment.

Neurally mediated syncope may occur in patients whose hemodynamic picture does not fit the characteristics of orthostatic intolerance as described elsewhere in this issue. Nonetheless, patients who suffer from neurocardiogenic or vasovagal syncope may be seriously incapacitated by their episodes of syncope or presyncope. Although it has been assumed that vagal activation as a result of stimulation of ventricular mechanoreceptors is essential to the production of these episodes, several critical observations are presented that suggest that other mechanisms may also be operative in some patient subsets. In addition, evidence is presented that the sympathetic responses of many of these patients may be reduced rather than increased and that abnormal baroreflex responsiveness may also play an causative role. These findings suggest new avenues for therapy in this field in which carefully controlled, randomized, double-blind trials are scarce.

[1]  Mark A. Hlatky,et al.  ACC/AHA GUIDELINES FOR IMPLANTATION OF CARDIAC PACEMAKERS AND ANTI ARRHYTHMIA DEVICES : EXECUTIVE SUMMARY , 1998 .

[2]  P. Flanagan,et al.  Effect of beta blockers on the time to first syncope recurrence in patients after a positive isoproterenol tilt table test. , 1996, The American journal of cardiology.

[3]  B. Deal,et al.  Randomized comparison of atenolol and fludrocortisone acetate in the treatment of pediatric neurally mediated syncope. , 1995, The American journal of cardiology.

[4]  K. Coyne,et al.  The autonomic and hemodynamic effects of oral theophylline in patients with vasodepressor syncope. , 1991, Archives of internal medicine.

[5]  M Linzer,et al.  Syncope: current diagnostic evaluation and management. , 1990, Annals of internal medicine.

[6]  M A Hlatky,et al.  ACC/AHA Guidelines for Implantation of Cardiac Pacemakers and Antiarrhythmia Devices: Executive Summary--a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee on Pacemaker Implantation). , 1998, Circulation.

[7]  R. Furlan,et al.  Yohimbine in neurally mediated syncope. Pathophysiological implications. , 1998, The Journal of clinical investigation.

[8]  B. Morgan,et al.  Vasovagal syncope after infusion of a vasodilator in a heart-transplant recipient. , 1990, The New England journal of medicine.

[9]  Abboud Fm.  Ventricular syncope: is the heart a sensory organ? , 1989 .

[10]  C. Gornick,et al.  Usefulness of disopyramide for prevention of upright tilt-induced hypotension-bradycardia. , 1990, The American journal of cardiology.

[11]  M. Goldberg,et al.  Yohimbine: a pharmacological probe for study of the alpha 2-adrenoreceptor. , 1983, Pharmacological reviews.

[12]  Richard Tressider.  The Surgical aid Society and its Methods , 1899 .

[13]  D. Robertson,et al.  The Bezold—Jarisch reflex: Possible role in limiting myocardial ischemia , 1981, Clinical cardiology.

[14]  J. Onrot,et al.  Oral yohimbine in human autonomic failure , 1987, Neurology.

[15]  J. Leonard,et al.  Vasodepressor Syncope: Factors Influencing Cardiac Output , 1957, Circulation.

[16]  M. Goldberg,et al.  Influence of yohimbine on blood pressure, autonomic reflexes, and plasma catecholamines in humans. , 1983, Hypertension.

[17]  L. Mont,et al.  Limitations of head-up tilt test for evaluating the efficacy of therapeutic interventions in patients with vasovagal syncope: results of a controlled study of etilefrine versus placebo. , 1995, Journal of the American College of Cardiology.

[18]  D. Benditt,et al.  Syncope: causes, clinical evaluation, and current therapy. , 1992, Annual review of medicine.

[19]  S. Su,et al.  Excessive myocardial contraction in vasovagal syncope demonstrated by echocardiography during head‐up tilt test , 1996, Clinical cardiology.

[20]  H. Heidbüchel,et al.  Tilt Training: A New Treatment for Recurrent Neurocardiogenic Syncope and Severe Orthostatic Intolerance , 1998, Pacing and clinical electrophysiology : PACE.

[21]  J. Rouleau,et al.  Impaired endothelin-1 release in tilt-induced syncope. , 1998, The American journal of cardiology.

[22]  R Furlan,et al.  Effect of standing on neurohumoral responses and plasma volume in healthy subjects. , 1998, Journal of applied physiology.

[23]  M. Forsling,et al.  The response of arginine vasopressin and plasma renin to postural change in normal man, with observations on syncope. , 1976, Clinical science and molecular medicine.

[24]  R. Furlan,et al.  Malignant vagotonia due to selective baroreflex failure. , 1997, Hypertension.

[25]  M. Yacoub,et al.  Vasovagal reactions may occur after orthotopic heart transplantation. , 1993, Journal of the American College of Cardiology.

[26]  J. Liard,et al.  Vasopressin in cardiovascular control: role of circulating vasopressin. , 1984, Clinical science.

[27]  H. Kaufmann.  Neurally mediated syncope: pathogenesis, diagnosis, and treatment. , 1995, Neurology.

[28]  D. Kosinski,et al.  Use of sertraline hydrochloride in the treatment of refractory neurocardiogenic syncope in children and adolescents. , 1994, Journal of the American College of Cardiology.

[29]  C. Morillo,et al.  Neural Monitoring of Vasovagal Syncope , 1997, Pacing and clinical electrophysiology : PACE.

[30]  P. Wolf,et al.  Epidemiologic features of isolated syncope: the Framingham Study. , 1985, Stroke.

[31]  Mark Linzer,et al.  CLINICAL GUIDELINE: Diagnosing Syncope: Part 2: Unexplained Syncope , 1997, Annals of Internal Medicine.

[32]  R. Hainsworth,et al.  Salt supplement increases plasma volume and orthostatic tolerance in patients with unexplained syncope. , 1996, Heart.

[33]  H. Kaufmann,et al.  Plasma endothelin during upright tilt: relevance for orthostatic hypotension? , 1991, The Lancet.

[34]  M. Biehl,et al.  Efficacy of Midodrine Hydrochloride in Neurocardiogenic Syncope Refractory to Standard Therapy , 1997, Journal of cardiovascular electrophysiology.

[35]  B. Grubb,et al.  Usefulness of Fluoxetine Hydrochloride for Prevention of Resistant Upright Tilt Induced Syncope , 1993, Pacing and clinical electrophysiology : PACE.

[36]  W. Kapoor,et al.  CLINICAL GUIDELINE: Diagnosing Syncope: Part 1: Value of History, Physical Examination, and Electrocardiography , 1997, Annals of Internal Medicine.

[37]  R. Sutton,et al.  Proposed classification for tilt induced vasovagal syncope , 1992 .

[38]  B. Wallin,et al.  Sympathetic outflow to muscles during vasovagal syncope. , 1982, Journal of the autonomic nervous system.

[39]  D L Eckberg,et al.  Vagal and sympathetic mechanisms in patients with orthostatic vasovagal syncope. , 1997, Circulation.

[40]  H. Morris,et al.  Malignant vasovagal syncope: prolonged asystole provoked by head-up tilt. Case report and review of diagnosis, pathophysiology, and therapy. , 1988, Cleveland Clinic journal of medicine.

[41]  I. Biaggioni,et al.  Chronic hypotension. In the shadow of hypertension. , 1992, American journal of hypertension.

[42]  K. Oldroyd,et al.  Increase in plasma beta endorphins precedes vasodepressor syncope. , 1993, British heart journal.

[43]  P. Vardas,et al.  The incidence of malignant vasovagal syndrome in patients with recurrent syncope. , 1991, European heart journal.

[44]  M. Goldberg,et al.  Assay of yohimbine in human plasma using high performance liquid chromatography with electrochemical detection , 1984 .

[45]  D Robertson,et al.  The causes of chronic orthostatic hypotension. , 1985, Ma zui xue za zhi = Anaesthesiologica Sinica.

[46]  M Akhtar,et al.  Echocardiographic demonstration of decreased left ventricular dimensions and vigorous myocardial contraction during syncope induced by head-up tilt. , 1991, Journal of the American College of Cardiology.

[47]  J. Netterville,et al.  The diagnosis and treatment of baroreflex failure. , 1993, The New England journal of medicine.

[48]  F. Fouad-Tarazi,et al.  The Usefulness of Head‐Up Tilt Testing and Hemodynamic Investigations in the Workup of Syncope of Unknown Origin , 1988, Pacing and clinical electrophysiology : PACE.

[49]  R. Hainsworth,et al.  Cardiovascular reflex responses in patients with unexplained syncope. , 1989, Clinical science.

[50]  N. Secher,et al.  Effect of serotonin receptor blockade on endocrine and cardiovascular responses to head-up tilt in humans. , 1993, Acta physiologica Scandinavica.

[51]  J. Onrot,et al.  Neck tumour with syncope due to paroxysmal sympathetic withdrawal. , 1987, Journal of neurology, neurosurgery, and psychiatry.

[52]  M. Carlson,et al.  Naloxone does not prevent vasovagal syncope during simulated orthostasis in humans. , 1993, Journal of the autonomic nervous system.

[53]  B. Grubb,et al.  Head‐upright tilt table testing for recurrent, unexplained syncope , 1993, Clinical cardiology.

[54]  W. Kapoor,et al.  CLINICAL GUIDELINE: Diagnosing Syncope: Part 1: Value of History, Physical Examination, and Electrocardiography , 1997, Annals of Internal Medicine.

[55]  M. Goldberg,et al.  Hypertensive effect of yohimbine following selective injection into the nucleus tractus solitarii of normotensive rats , 1983, Brain Research.

[56]  C. Gornick,et al.  Provocation of bradycardia and hypotension by isoproterenol and upright posture in patients with unexplained syncope. , 1989, The New England journal of medicine.

[57]  J. Strasburger,et al.  Usefulness of metoprolol for unexplained syncope and positive response to tilt testing in young persons. , 1993, The American journal of cardiology.

[58]  D. Kosinski,et al.  The Use of Methylphenidate in the Treatment of Refractory Neurocardiogenic Syncope , 1996, Pacing and clinical electrophysiology : PACE.

[59]  R Furlan,et al.  Sympathetic and baroreceptor reflex function in neurally mediated syncope evoked by tilt. , 1997, The Journal of clinical investigation.

[60]  M. Goldberg,et al.  Use of alpha 2 adrenoreceptor agonists and antagonists in the functional assessment of the sympathetic nervous system. , 1986, The Journal of clinical investigation.

[61]  F. Jaeger,et al.  Is Absolute Hypovolemia a Risk Factor for Vasovagal Response to Head‐Up Tilt? , 1993, Pacing and clinical electrophysiology : PACE.

[62]  A. Mark.  The Bezold-Jarisch reflex revisited: clinical implications of inhibitory reflexes originating in the heart. , 1983, Journal of the American College of Cardiology.

[63]  M Linzer,et al.  Diagnosing syncope. Part 2: Unexplained syncope. Clinical Efficacy Assessment Project of the American College of Physicians. , 1997, Annals of internal medicine.

[64]  B. Ditto,et al.  Baroreflex sensitivity at rest and during stress in individuals with a history of vasovagal syncope. , 1991, Journal of psychosomatic research.

[65]  C. W. Hart,et al.  An approach to the dizzy patient , 1972, Neurology.

[66]  D. Kosinski,et al.  Neurocardiogenic syncope: response to hormonal therapy. , 1997, Pediatrics.

[67]  P. Thorén,et al.  Increased activity in left ventricular receptors during hemorrhage or occlusion of caval veins in the cat. A possible cause of the vaso-vagal reaction. , 1972, Acta physiologica Scandinavica.

[68]  C. Morillo,et al.  Can serial tilt testing be used to evaluate therapy in neurally mediated syncope? , 1996, The American journal of cardiology.

[69]  J. Barbey.  Vasodepressor syncope. Diagnosis and management. , 1997, Cardiology clinics.

[70]  S. Fortney,et al.  Occurrence of presyncope in subjects without ventricular innervation. , 1993, Clinical science.