[Catecholamine plasma levels during the tilt-table test in patients with vasovagal syncope]

The head-up tilt test (HUT) makes it possible to diagnose vasovagal syncope. The objective of the trial was to follow up changes of catecholamine plasma levels during HUT and test their importance in the pathogenesis of vasovagal syncope.

In 25 patients with syncope of obscure etiology during HUT the noradrenalin, adrenalin and dopamine levels were followed up. In 125 patients (8 men and 7 women, mean age 34.3 years) HUT was positive. The control group was formed by 10 patients with negative HUT (4 men, 6 women, mean age 41.1 years). The catecholamine levels were assessed by the method of high resolution liquid chromatography during minutes 0, 5 and after completion of the test (i.e. during development of the syncope or the 45th minute). On comparison by the t-test no statistically significant difference between the group with vasovagal syncope and the control group was found. Noradrenalin 0 min: 186.4 +/- 61.6 pg/ml vs. 190.5 +/- 67.4 pg/ml (n.s.), 5th min. 506.3 +/- 178.9 pg/ml vs. 566.8 +/- 195.6 pg/ml (n.s.), end of test 457.3 +/- 154.1 pg/ml vs. 352.3 +/- 169.9 pg/ml (n.s.). Adrenalin 0 min. 54.0 +/- 12.6 pg/ml vs. 54.9 +/- 13.6 pg/ml (n.s.), 5th min. 114.3 +/- 35.6 pg/ml vs. 128.1 +/- 41.0 pg/ml n.s., end of test 98.2 +/- 40.6 vs. 783 +/- 31.2 pg/ml (n.s.). Dopamine 0 min. 113.9 +/- 36.5 pg/ml vs. 158.4 +/- 67.2 pg/ml (n.s.), 5th min. 318.1 +/- 72.7 vs. 328.5 +/- 119.7 pg/ml (n.s.), end of test 279.4 +/- 93.8 pg/ml vs. 231.7 +/- 98.5 pg/ml (n.s.).

Catecholamine plasma levels in patients with vasovagal syncope did not differ from the control group. The importance of catecholamines in the pathogenesis of vasovagal syncope thus cannot be confirmed.