Initial orthostatic hypotension as a cause of syncope in an adolescent

Syncope or particularly pre-syncope upon standing is observed much more commonly in the young than in adults. Almost all teenagers and adolescents are familiar with a brief feeling of lightheadedness and some visual blurring within a few seconds of standing up quickly. Symptoms typically resolve spontaneously within 20 seconds. Such complaints are most common after prolonged supine rest or after arising from the squatted position (see Casus 2 and 3 in this section)[2][1][3]. The complaints are caused by a transient fall in arterial pressure which occurs upon active standing. This transient fall in blood pressure during active standing is a physiological response[4]. However, normally blood pressure does not drop for more than -40 mmHg systolic and -20 mmHg diastolic[1].This initial drop in blood pressure is less dramatic or not at all present upon a passive head-up tilt. In some instances the symptoms are severe and true syncope may occur upon standing in otherwise healthy subjects. A recent study in 394 medical students showed that in 8% standing up was the trigger for transient loss of consciousness[5].

The initial transient fall in pressure in normal young subjects is caused by vasodilatation in active muscles during standing up[4]. Patients with the most severe complaints tend to be tall with an asthenic habitus and poorly developed musculature[6]. Often the patients also have a postural tachycardia and a tendency to faint during prolonged standing[7][8]. For the diagnosis of initial orthostatic hypotension history taking is the most important tool. The onset of symptoms between 5-10 s and disappearance within 20 seconds is typical for this clinical condition. The diagnosis can only be confirmed by an active standing test with continuous blood pressure monitoring using a Finapres device. A positive test (symptoms and an abnormally large initial fall in finger bloodpressure) is a very specific, but in our experience not a sensitive test. Because initial orthostatic hypotension is associated with active arising, tilt testing (i.e. head up tilting) is not the provoking test and not indicated.

Treatment of initial orthostatic hypotension is symptomatic. Goal is to diminish the drop in blood pressure during standing up. A clear explanation of the underlying mechanism and avoidance of the main triggers (rapid raise) are the main treatment-options. A novel approach is training in blood pressure rising manoeuvres. We have found lower body muscle tensing immediately after standing up very effective to decrease the fall in pressure[9].(see also Casus 3 in this section). In addition volume-expansion can be applied by raising water- and salt-intake[10]. In severe cases head-up sleeping or pharmacological treatment with mineralocorticoids (fludrocortisone) can be considered (see Casus 7 in this section].