Age-Related Head-Up-Tilt Test Cardiac-Hemodynamic Profile in Vasovagal Syncope

Abstract

Objective To determine the age-related cardio-hemodynamic profile (CHP) during head up tilt test (HUT) in patients with neurally mediated syncope (NMS). Methods 97 subjects (M/F=43/54) with a clinical history of NMS and normal structural heart underwent HUT (70°) 30-minute protocol. 73 patients had positive HUT response (mean time to syncope of 19±7 min) and were included for study analysis. Patients were divided in three study groups for comparison according to age: A = 66 years old (77±6). Beat-to-Beat heart rate (HR, bpm), mean blood pressure (MAP) and cardiac impedance were recorded and total peripheral resistance index (TPRI, dyne*s*m2/cm^5) and left ventricular work index (LVWI, mmHg*l/min/m2) were calculated using the Task Force Monitor (CNSystem, AU). Variables were compared at rest, 5 minutes of HUT (ES) and during -2 and -5 minutes prior to the onset of syncope. One-way ANOVA and Student's t test were applied. Results Variables are shown as means ± SD. Increased baseline HR was found in younger patients (Group A) compared with group B and C (76±15 vs. 67±12, p=0.017; 76±15 vs. 69±11, p=0.076). No statistical differences were found in MAP during HUT comparing groups. TPRI and LVWI are shown in the table as follows ![Graphic][1] Conclusion Distinct age-related CHP alterations can be documented in patients with NMS provoked by HUT. Younger NMS patients have an increased chronotropic and inotropic activity during rest and OS as well as a decreased vascular reactivity during HUT. Central and peripheral cardiovascular compensatory mechanisms during orthostatic stress may trigger distinct vasovagal responses that vary depending on age. [1]: /embed/graphic-1.gif