Arterial rigidity and cardiovascular vagosympathetic activity in normotensive and hypertensive obese patients and type 2 diabetics

An increase in arterial rigidity is associated with a poor cardiovascular prognosis. Several studies have suggested that an increase in sympathetic activity may be involved in essential hypertension. We have recently shown that vagal control of heart rate (HR) variations during standardised tests is altered in normotensive obese and diabetic patients. The aim of the present study was to compare cardiovascular vagosympathetic activity in obese and type 2 diabetic patients, either normotensive or hypertensive, and to investigate the relationship between pulse pressure (an index of arterial rigidity) and sympathetic activity in this population. Seventy normotensive obese and 32 mildly hypertensive obese patients. 18 normotensive type 2 diabetic patients and 14 mildly hypertensive type 2 diabetic patients were compared with 21 control subjects. Finapres studied HR and blood pressure variations. In the four groups, during a 6-min period at a controlled breathing rate, the high frequency peak of HR variations was significantly reduced (p<0.001). The mid-frequency peak of systolic BP variations in the standing position, which depends on sympathetic activity, did not differ significantly between the four groups and control subjects. In obese and diabetic hypertensive patients, this peak correlated significantly with pulse pressure measured in the lying position (r=0.379; p=0.043 and r=0.81; p<0.0001, respectively). This study 1. confirms that vagal control of HR variations is reduced to a similar extent in obese and diabetic patients; and 2. suggests that cardiovascular sympathetic activity is relatively increased in these patients without significant difference between normotensive and hypertensive patients, but interestingly that the increase in arterial rigidity is associated with a higher sympathetic activity.