Mental Stress, Autonomic Function, and Heart Disease

BACKGROUND:

The strong association between mental stress and morbid cardiovascular events in coronary artery disease (CAD) patients may derive from stress-induced cardiac ischemia due to exaggerated increases in vascular resistance and arterial pressure. In fact, this may explain part of the prognostic relationship of baroreflex cardiac vagal control to cardiovascular outcome among CAD patients. The hemodynamic responses to psychological stress are buffered by the arterial baroreflex; thus, exaggerated pressor responses to mental stress may result from impaired baroreflex regulation in CAD patients.

DESIGN NARRATIVE:

The study has three components. The first component characterizes the relationships between vascular stiffness and baroreflex regulation among CAD patients, also contrasting healthy control subjects with CAD patients. The second component examines, in relation to individual differences in pharmacologically derived estimates of baroreflex function, changes in autonomic and baroreflex control during laboratory psychological stress among CAD patients and among healthy control subjects. The third component tests the hypothesis that impaired baroreflex regulation in CAD patients, due to increased vascular stiffness and/or attenuated autonomic control, is associated with exacerbated hemodynamic reactions to psychological stress. Bolus vasoactive drug infusions in combination with Finapres beat-by-beat arterial pressures and carotid B-mode ultrasonography are used to evaluate baroreflex sensitivity and arterial stiffness. Baroreflex adjustments to psychological stress are assessed by power spectral-derived relations between arterial pressure and cardiac chronotropy during a mental arithmetic task and a speech task. The degree to which indices of baroreflex function are associated with hemodynamic responses to psychological stress among CAD patients is assessed.