[Orthostatic intolerance syndromes]

In patients with an orthostatic intolerance, the hemodynamic response to standing, may identify an abnormality know as postural orthostatic tachycardia syndrome or orthostatic hypotension, that can often be treated without further testing. When the response to standing is normal, tilt-table testing may be useful in making the diagnosis of vasovagal syncope or postural orthostatic tachycardia syndrome and guiding treatment. In evaluating the results of tilt-table testing, an important consideration is the distinction between vasovagal syncope, and the dysautonomic response to tilt characterized by a gradual and progressive decrease in blood pressure that leads to syncope. Current practice patterns suggest that beta blockers, fludrocortisone, and midodrine are commonly used to treat patients with vasovagal syncope. These also suggest that patients with the postural orthostatic tachycardia syndrome, and with the dysautonomic response, are better treated with fludrocortisone and midodrine.