ISOPROTERENOL TEST AND HEAD-UP TILT TEST FOR DIAGNOSIS OF VASOVAGAL SYNCOPE IN ELDERLY PATIENTS

The elderly can be affected by vasovagal syncope, but they often do no t have preceding symptoms. The head-up tilt test (HTT) is successfully used in half of the patients in which the diagnosis is difficult. In young people the association with the isoproterenol test improves the sensitivity of the HTT. In the elderly the effect of such an associati on is still debated, therefore, the present study was aimed at evaluat ing the usefulness of the association between the two tests in old sub jects to unmask the vasovagal nature of some syncopes of unknown origi n. Twenty-four patients with negative HTT (18 males and 6 females; mea n age 65 years) 10 with and 14 without organic heart disease were stud ied. The test protocol consisted of a continuous intravenous infusion of isoproterenol in successive stages starting from a dosage of 1 gamm a/min for 5 min in supine position and then for 10 min in passive upri ght position at 80 degrees (Ist stage) up to maximum of 5 gamma/min (5 th stage). The results obtained were: 72 patients (50 %) had a positiv e test (reproduction of syncope) with a vasodepressor response in 6 of them and a mixed response in 6 patients. The mean time to syncope was during the 4th min of the 4th stage of treatment. The heart rate incr ease was 36 $ between the initial and peak values achieved during the test in patients with a positive test, and 10.5 %, in patients with ne gative test (p < 0.05). These results indicate that the isoproterenol test seems to increase the sensitivity of HTT in elderly patients with syncope of unknown origin.