Vasovagal syncope

In a placebo-controlled study in 48 patients with active rheumatoid arthritis, CD4 blockade produced clinical benefit (5). Adverse events were reported in 97% of the patients, compared with 73% of those given placebo. In both groups most of the events were mild to moderate. Serious adverse events were reported in five patients who received anti-CD4 syncope/vasovagal attacks (n = 3), back pain (n = 1), abdominal pain/rectal bleeding (n = 1). Skin rashes occurred in 62% of the patients who received the antibody. In five cases a skin biopsy was performed, and showed a cellular infiltration centered on the blood vessels, suggesting a drug-induced vasculitis. 

Vasovagal syncope has traditionally been treated successfully with oral /L blockers (e.g., metoprolol) to inhibit the sympathetic surge that causes... 

Transdermal scopolamine (hyoscine) was introduced in the 1980s as a convenient alternative for the prevention of motion sickness. It is also effective in reducing of nausea and vomiting after ear surgery but was not found to be useful in the prevention of vasovagal syncope (see Chapter 14). 

The success rate is dependent on the dose, the duration of the infusion, and parity of the woman. Dose-limiting adverse effects include vomiting, diarrhea, fever, and bronchoconstriction. Hypotension, hypertension, syncope, dizziness, and flushing can occur and may be related to the vasomotor and vasovagal effects of PGE2. 

Affective and Mental Disorders. Anxiety and emotional instability can be associated with psychogenic reactions, such as vasovagal syncope, that may appear to be drug related. Medications used to treat these disorders may potentiate the activity of ophthalmic medications. The use of monoamine oxidase inhibitors or tricyclic antidepressants can enhance the systemic effects of topically applied phenylephrine and a2-adrenergic agonists. 

A 48-year-old hypertensive physician, who had optimal blood pressure control after taking oral amlodipine 5 mg/day for 3 months, developed a slight frontal headache and fever, thought that he had malaria, and took four tablets of chloroquine sulfate (total 600 mg base). Two hours later he became nauseated and dizzy and collapsed his systolic blood pressure was 80 mmHg and his diastolic pressure was unrecordable, suggesting vasovagal syncope, which was corrected by dextrose-sahne infusion. 

Calkins H. Pharmacologic approaches to therapy for vasovagal syncope. Am J Cardiol 1999 84(8A) Q20-5. 

Alternatively, bradycardia can accompany hypotension or syncope (25-27), presumably due to a vagal effect (it is responsive to atropine) complete heart block has also been reported (28). Occasionally, similar events occur in patients without ischemic heart disease (29), suggesting a mechanism similar to vasovagal syncope or coronary artery spasm (30,31) rather than coronary steal. 

Vasovagal syncope usually can be treated successfully with oral 8-blockers. Although these agents may seem inappropriate to treat a syndrome resulting from vasodilation and bradycardia, the therapeutic approach is designed to block an inappropriate vasovagal reaction. 

Syncope is the abrupt and transient loss of consciousness due to a temporary reduction in cerebral blood flow. It is associated with an absence of postural tone and followed by a rapid and usually complete recovery. Syncope may be both benign or the only warning before an episode causing sudden death (1). Recurrent episodes of syncope may result from a variety of disorders, all of which cause a temporary reductiou iu cerebral blood flow sufficient to disturb the normal functions of the brain. Neurocardiogenic (vasovagal) syncope is the most common of a group of reflex (neurally mediated) syncopes, characterized by a sudden failure of the autonomic nervous system (ANS) to maintain blood pressure, and occasionally heart rate, at a level sufficient to maintain cerebral perfusion and consciousness (2-4). Syncope accounts for 3.5% of all emergency room visits and 1-6% of all hospital admissions annually in the USA (5). 

Situational vasovagal syncope in which avoidance behavior is effective. 

---