Background: Exaggerated carotid sinus stimulation (CSStim) responses are associated with advancing age, hypertension, and atherosclerotic disease. However, there is little information regarding the contribution of the functional arterial status in the degree of CSStim responses at the very early stages of the hypertensive disease.
Methods: Carotid sinus stimulation (with simultaneous recordings of the electrocardiogram (ECG) and the blood pressure [BP] at the brachial artery) was performed in 90 newly diagnosed patients with stage I to II essential hypertension (aged 54 +/- 10 years; office BP, 154/97 mm Hg) and in 75 normotensive controls matched for age and sex. The cardioinhibitory type of CSStim responses was evaluated by calculating an index defined as the ratio of the longest R-R interval on the ECG recording during stimulation to R-R interval at rest. Common carotid artery (CCA) distensibility was calculated as a function of changes in diameter (determined by echocardiography) and pulse pressure (determined sphygmomanometrically at the brachial artery).
Results: The two groups did not differ regarding the demographic and laboratory data. Hypertensive subjects compared to controls had decreased CCA distensibility (1.18 v 1.64 dyne(-1) cm(2) 10(-6), P <.005) and increased CSStim responses index (1.74 +/- 1.03 v 1.37 +/- 0.99, P <.001). By using a multivariate model including age, office pulse pressure, left ventricular mass index, and CCA distensibility, it was revealed that only CCA distensibility was a significant determinant of CSStim responses index (P <.005).
Conclusions: Hypertension-induced alterations in CCA elastic properties accompany changes in CSStim responses. These findings may contribute to the understanding of the mechanisms between atherosclerotic disease and CSStim responses.