THE REDUCTION OF CAROTID BODY VOLUME IN RESISTANT HYPERTENSIVE PATIENTS IS ASSOCIATED TO DIABETIC CONDITION

Objective: Considering that carotid bodies (CB) are involved in the counterregulatory response to hypoglycemia and that their impact on blood pressure control still needs to be better clarified, the objective of this study was to characterize the volumetric reduction of CB in controlled and uncontrolled hypertensive patients. Design and method: CT angiograms of hypertensive patients treated at the Heart Institute (University of São Paulo Medical School) were studied. The patients were separated into four groups: hypertensive (receiving 1 to 2 categories of antihypertensives) with controlled (H-C, n=44) and uncontrolled (H-U, n=43) blood pressure, and resistant hypertensives (receiving 3 or more categories of antihypertensives) with controlled (RH-C, n=11) and uncontrolled (RH-U, n=7) blood pressure. CT angiograms (Aquilion ONE/PRISM–Canon) of cervical arteries with iodinated contrast were evaluated. Artery reconstructions used 0.5 mm thick sections, with orthogonal measurements of CB to evaluate bilateral carotid diameters and bifurcations. Results: The morphology of common, internal and external carotid arteries was very similar between the groups. The mean age between groups was not significantly different (H-C: 68±12; H-U: 64±14; HR-C:70±10; HR-U: 60±12 years). When evaluating the presence of atherosclerotic lesions, a higher percentage was found in RH groups (82 and 71%) when compared to hypertensive groups (57 and 46%). Despite the presence of diabetes did not show differences between groups, the volume (mm3) of carotid bodies in the presence of diabetes, was significantly reduced in resistant hypertensive (HR-C and HR-U: -79%) if compared to hypertensive patients (H-C and H-U: -21%). Conclusions: The reduction of CB volume may be associated with the loss of microvascularization, mediating a possible hyperactivity of CB, which consequently maintain the comorbidities observed in these patients. Experimental studies showed that bilateral resection of the carotid sinus nerve completely prevents insulin resistance and hypertension, reinforcing the strong effect of diabetes upon normal function of CB as found in this study. Longitudinal studies will contribute to a better understanding of CB regulation and the impact of diabetic state on blood pressure control.