Cardiovascular responses to isometric handgrip exercise in young patients with recurrent vasovagal syncope

Arterial blood pressure (BP) increased in healthy humans in response to isometric handgrip (IHG), but the pattern of the relative contribution of cardiac output (CO) and total peripheral resistance (TPR) changes to the pressor response is different among individuals. We investigated weather patients with recurrent vasovagal syncope (VVS) have a similar pattern of individual CO, TPR and pressor responses to IHG, as healthy subjects.

32 patients (27.5 ± 2.6 years), and 30 age-matched controls. Autonomic function was evaluated using finger-photoplethysmography to measure BP and heart rate (HR) response to gravitational stress (ΔBP, ΔHR), Valsalva maneuver (VM) and baroreflex sensitivity (BRS), and BP HR and CO changes during IHG.

ΔBP, ΔHR, VM and IHG tests did not show significant difference between VVS patients and controls, although BRS was lower in VVS group (p < 0.05). Pattern of individual pressor, CO and TPR responses to IHG was significantly different between VVS patients and healthy subjects (Chi square, p = 0.0246). In 100% of the healthy subjects BP increased during IHG, but in a 19% of the patients BP (CO and TPR) did not increased during IHG. In VVS patients, the autonomic tests (ΔBP, ΔHR, VM and BRS) showed no significant differences between the group with BP increase and the group without pressor response.

In VVS patients, the pattern of individual CO and TPR changes to IGH is different from healthy subjects. VVS patients may present an abnormal regulation of cardiovascular responses to IHG, with preserved cardiovagal and cardiac sympathetic function.