Mental Stress Pressor Response and Post‐Stress Aortic Wave Reflection

Abstract

Reactivity to mental stress has been linked to cardiovascular risk, and is shown to negatively influence aortic wave reflection for up to an hour after acute mental arithmetic. It has been postulated that sympathetic catecholamine release during the stressful task drives the sustained elevation in wave reflection. In the present study we sought to determine how muscle sympathetic nerve activity (MSNA) and mean arterial pressure (MAP) reactivity influence post mental stress aortic augmentation index (AIx). Twenty‐seven volunteers (25±1 years) with resting blood pressure ≥120/80 mmHg participated in the present study. Baseline pulse wave analysis and pulse wave velocity recordings were assessed on participants after 10 minutes of supine rest. Participants were then instrumented for measurements of MSNA (microneurography), beat‐to‐beat blood pressure (finger plethysmography), and heart rate (3‐lead ECG). Subsequently MSNA, blood pressure, and heart rate were measured during a 5‐minute baseline, 5‐minute mental stress task (serial subtraction), and 5‐minute recovery. Finally, aortic wave reflection (i.e. AIx) was reassessed 10 minutes after completion of mental stress. Statistical analyses included paired t‐tests to compare MSNA, MAP, heart rate (HR), and perceived stress during baseline and mental stress. We used standard multiple regression with change in AIx as the dependent variable and changes in MSNA, MAP, and perceived stress as the independent variables. Means were considered significantly different when p<0.05. The mental stress task significantly increased HR (Δ15±2 beats/minute), MAP (Δ14±1 mmHg), and perceived stress (Δ1.9±0.1 a.u.), while MSNA was not significantly increased. There was however a range of changes in MSNA from ‐13 to +20 bursts/minute. The change in MAP during mental stress was a significant predictor (ꞵ=0.47; p=0.03) of the change in AIx (post‐stress vs. baseline). Changes in MSNA and perceived stress were not predictors of mental stress‐related changes in AIx. Our results indicate that the aortic wave reflection responses to mental stress appear to be linked to the pressor response, but not sympathetic or perceived stress responses. This is novel preliminary data that suggests there may not be a direct link between sympathetic activation and aortic wave reflection following cognitive stress.