Left ventricular performance during psychological stress

Left ventricular ejection fraction, systolic blood pressure and plasma norepinephrine were measured in six normotensive and six mildly hypertensive subjects during rest and psychological stress. Compared with rest, 8 of the 12 subjects developed significant (P less than 0.05) changes in ejection fraction (increase in 6, decrease in 2); 10 of 12 subjects developed significant elevations of plasma norepinephrine; and all developed significant increases in systolic blood pressure. When the stress effects were examined for the total group, as opposed to within subjects, there were significant increases in plasma norepinephrine (P less than 0.001) and systolic blood pressure (P less than 0.001) but, interestingly, mean ejection fraction and stroke volume remained unchanged, implying stress led to increased left ventricular contractility.