The tilting cardiovascular response in orthostatic syncope.

159 patients with a previous discharge diagnosis of recurrent vasodepressor syncope associated with prolonged standing or other circumstance known to trigger the condition were examined in order to isolate the orthostatic form. 72 patients with a history of at least two episodes of loss of consciousness after standing still for at least 10' were selected for testing by head-up tilt. Those who showed signs or symptoms during the test were tested a further twice, the third time after atropine administration. This process resulted in the diagnosis of orthostatic vasodepressor syncope in 28 patients who presented both 1) a positive test associated with hypotension and bradycardia and 2) bradycardia-free hypotention on repetition of the test with atropine.