Propranolol to Treat Fainting Due to Sympathoadrenal Imbalance

INCLUSION CRITERIA: Subjects are patients referred for evaluation of chronic orthostatic intolerance. Patients enter into the therapeutic trial after they are determined to have NCS with SAI in a screening evaluation. Participation in this protocol is offered to individuals 18 years old or older, independently of gender, race, advanced age, ethnicity, religion, or any demographic or sociopolitical classifications. EXCLUSION CRITERIA: Age: Minors younger than 18 years old are excluded. Advanced age does not constitute an exclusion criterion. Risk: A candidate subject is excluded if, in the judgement of the Principal Investigator or Clinical Director, protocol participation would place the subject at subject at substantially increased acute medical risk. This includes the risks associated with air travel to the NIH. A candidate subject is excluded if, in the opinion of the Principal Investigator or Clinical Director, the medical risk outweighs the potential scientific benefit. Disqualifying Conditions: A candidate subject is excluded if there is a disqualifying condition. Examples of disqualifying conditions are history of asthma or chronic obstructive pulmonary disease requiring bronchodilators, hepatic or renal failure, atrioventricular block of any degree, bradycardia, symptomatic congestive heart failure, severe anemia, psychosis, refractory ventricular arrhythmias, symptomatic coronary heart disease, insulin-dependent diabetes mellitus, Wolff-Parkinson-White syndrome, and peripheral vascular disease. Patients with known or suspected allergy or hypersensitivity to propranolol are excluded from this study. A positive HIV test result does not necessarily exclude a patient from participating. Medications: A candidate subject is excluded if clinical considerations require that the patient continue treatment with a drug likely to interfere with the scientific results. Patients who must take medications daily in the following categories are excluded: anticoagulants, tricyclic, antidepressants, barbiturates, aspirin, acetaminophen, insulin, bronchodilators. Patients unable to discontinue nicotine, caffeine, or alcohol temporarily are excluded. Patients with chronic alcohol intake are excluded. Patients are not to discontinue any medications before the patient or the patient's doctor discusses this with the Principal Investigator, an Associate Investigator, or Research Nurse. If it is decided that discontinuing medications would be unsafe, then the patient is excluded from the study. Herbal Medicines and Dietary Supplements: Certain herbal medicines or dietary supplements are known or suspected to interfere with the experimental results, and such herbal medicines or dietary supplements must be discontinued before enrollment in the study. For many herbal medicines or dietary supplements, the mechanisms of action and therefore the possible effects on the experimental results are unknown. In cases where the subjects wish to continue their herbal medicines or dietary supplements while on study, and search of the available medical literature fails to identify effects that are known or expected to interfere with the experimental results, then the subjects may participate. Practical Limitations: Patients in whom we feel it would be difficult to technically to carry out the testing procedures are excluded. Pregnancy: Pregnant or lactating women are excluded. A blood test for pregnancy will be conducted on women of childbearing potential, before intake evaluation and also before each drug treatment phase. During the course of the protocol, subjects who are women of childbearing potential will be advised to practice adequate contraception. Termination of Participation: Subjects may refuse certain tests or procedures, or may terminate participation early, without loss of benefits to which they were previously entitled. The Investigators may also exclude a subject from further participation, such as in the event of known or suspect falsification of medical history information or refusal to undergo planned tests or procedures, without loss of benefits to which the subject was previously entitled.