Pharmacotherapy of Neurally Mediated Syncope

Abstract

Abstract-A wide variety of pharmacological agents are currently used for prevention of recurrent neurally mediated syncope, especially the vasovagal faint. None, however, have unequivocally proven long-term effectiveness based on adequate randomized clinical trials. At the present time, ␤-adrenergic receptor blockade, along with agents that increase central volume (eg, fludrocortisone, electrolyte-containing beverages), appear to be favored treatment options. The antiarrhythmic agent disopyramide and various serotonin reuptake blockers have also been reported to be beneficial. Finally, vasoconstrictor agents such as midodrine offer promise and remain the subject of clinical study. Ultimately, though, detailed study of the pathophysiology of these syncopal disorders and more aggressive pursuit of carefully designed placebo-controlled treatment studies are essential if pharmacological prevention of recurrent neurally mediated syncope is to be placed on a firm foundation. (Circulation. 1999;100:1242-1248.)Key Words: syncope Ⅲ nervous system Ⅲ pharmacology Ⅲ Cardiovascular Drugs N eurally mediated (neurocardiogenic) syncope comprises a number of clinical conditions in which symptomatic systemic hypotension occurs as a result of a transient disturbance of neural reflex cardiovascular control (Table 1). [1][2][3] The vasovagal faint, carotid sinus syndrome, and postmicturition syncope are the most common forms of the neurally mediated faint. Others, including cough syncope and postexertional syncope, are less frequently encountered.This communication focuses on the pharmacological options that have been proposed for preventing neurally mediated faints, and especially the vasovagal faint, because it has been the most thoroughly studied. The objective is to provide an overview of the pharmacology and pertinent proposed modes of action of those agents that may be of benefit. Drug Therapy of Neurally Mediated Syncope: Basic PrinciplesMost individuals who experience a neurally mediated faint (particularly vasovagal fainters) require no additional therapy beyond education (ie, recognition of premonitory symptoms, avoidance of triggering events, and awareness of useful evasive actions) and reassurance regarding the non-lifethreatening nature of the condition. On occasion, stress and anxiety management may be warranted. Various more aggressive nonpharmacological (eg, support hose, extended exposure to upright posture, pacemakers) and pharmacological treatment options are usually reserved for those relatively few individuals who experience frequent syncope and/or when symptoms cause excessive lifestyle difficulties, threaten employment, or result in unacceptable risk of physical injury to the patient or others.Currently, drugs are used for both diagnostic and therapeutic purposes in the patient with neurally mediated syncope. [1][2][3] In terms of diagnostic applications, agents such as isoproterenol, edrophonium, nitroglycerin, and adenosine have been reported to be helpful during tilt-table testing (ie, so-called pharmacolog...

Permanent Cardiac Pacing Versus Medical Treatment for the Prevention of Recurrent Vasovagal Syncope

“…4 -6,23 In general, pharmacological treatment is usually considered the first option for the prevention of recurrent vasovagal episodes, even if the evidence in favor of such an approach is scarce. 5,6 Moreover, long-term compliance with drug therapy is far from satisfactory, with side effects or adverse reactions causing frequent withdrawals. 5,6 Conversely, recent studies have suggested that cardiac pacing may significantly relieve symptoms in specific subsets of highly symptomatic vasovagal fainters.…”

“…3,4 Consequently, highly symptomatic subjects with excessive lifestyle difficulties are usually considered for a specific treatment. 4,5 In general, the available therapeutic options for vasovagal syncope can be broadly classified as long-term pharmacological therapy and permanent dual-chamber cardiac pacing. 4 -6 Although medical therapy should be effective in preventing the development of the vasovagal reflex, cardiac pacing is expected to contrast the reflex just after its appearance.…”

“…[7][8][9] As a matter of fact, in clinical practice, ␤-blockers currently represent the most widely prescribed drug class in patients with recurrent vasovagal spells. 5,6 On the other hand, after several observational studies, 10,11 2 randomized, controlled trials have suggested that cardiac pacing may represent a reasonable therapeutic alternative in highly symptomatic vasovagal fainters. 12,13 However, despite the existence of substantial literature on both pharmacological and pacing treatment, the relative efficacy of any specific option in patients with recurrent vasovagal spells is still a matter of dispute.…”

The use of vasoconstrictors in patients with cirrhosis: Type 1 HRS and beyond

“…44 Elimination is via the urine. 44 No pharmacokinetic evaluation of midodrine and its metabolite in patients with type 1 HRS has been performed. Previous clinical studies conducted in these patients used different doses of midodrine (Table 4).…”

Anti-stress Effects of 20(<i>S</i>)-Protopanaxadiol and 20(<i>S</i>)-Protopanaxatriol in Immobilized Mice

“…), which are γ-aminobutyrate A (GABA A ) receptor antagonists 25,26) or WAY-100635 (0.5 mg/kg, i.p. ), which is a 5-HT 1A receptor antagonist, 27) in mice exposed to immobilization stress (Fig. 2).…”