Influência de diferentes posturas na sensibilidade barorreflexa e nas respostas cardiovasculares ao exercício isométrico em pacientes com doença arterial coronariana

Abstract

The first study aimed to verify the relationship between baroreflex sensitivity (BRS) and carotid intima media thickness (IMT) considering a large set of SBR values. 56 men aged between 40-65 years were divided into 3 groups: healthy (H, n = 19), patients with coronary artery disease (CAD, n = 18) and CAD patients with diabetes mellitus (DM) type 2 (CAD-DM, n = 19). The BRS was evaluated in supine (SUP) and standing (STAND) positions through time domain, spectral and cross-spectral and closed-loop model based approaches. The IMT was evaluated over the right and left common carotid arteries. We conclude that the relationship between IMT and BRS is maintained even when considering a wide range of BRS values, supporting the idea that a noninvasive BRS estimate could be used to track modifications in cardiac baroreflex control. The second study aimed to investigate the cardiovascular (CV) responses during submaximal isometric contractions (handgrip) performed in different postures. 30 men aged 40-65 years were divided into 2 groups: healthy (H, n = 15) and patients with coronary artery disease (CAD, n = 15). Systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR) and peripheral vascular resistance (PVR) were measured at rest (BASELINE), exercise peak (PEAK) and in the 1st (REC1) and 9th (REC9) minute of recovery. The subjects performed four submaximal handgrip contractions at 15, 30, 45 and 60% of maximum voluntary contraction performed in supine (SUP), seated (SEAT) and STAND positions. In conclusion, lower CV stress was observed in SUP for the H group while the CAD group had a worse exercise position responsiveness when compared to the H group regarding SBP, DBP and PVR. So, the general conclusion is that there is an inverse relationship between BRS and IMT and its relationship is dependent of the method used to calculate BRS and, regarding the CV responses to isometric exercise, the supine posture promotes low CV stress in healthy subjects while the CAD group has higher SBP peak and worse exercise position responsiveness regarding SBP, DBP and PVR.