Morning rise of blood pressure and subcutaneous small resistance artery structure.

OBJECTIVES: It has been previously demonstrated that the morning rise (MoR) of blood pressure (BP) may predict major cardiovascular events in hypertensive patients. Structural alterations of small resistance arteries, as evaluated by the tunica media to internal lumen ratio (M/L) of subcutaneous small resistance arteries, may also predict cardiovascular events. Because an increased M/L may amplify the effect of hypertensive stimuli, the present study aimed to evaluate the possible relationships between MoR and M/L in a population of hypertensive patients.
METHODS: Sixty-four patients with essential hypertension were included in the present study. All patients were submitted to a biopsy of subcutaneous fat. Small resistance arteries were dissected and mounted on an isometric myograph, and the M/L was measured. In addition, MoR was calculated from ambulatory blood pressure monitoring (ABPM) according to four previously published different methods (MoR1 to MoR4).
RESULTS: A statistically significant correlation was observed between M/L and MoR1 (r = 0.52, P < 0.001), MoR2 (r = 0.32, P < 0.01), MoR3 (r = 0.25, P < 0.05) and MoR4 (r = 0.27, P < 0.05), as well as between internal diameter of subcutaneous small arteries and MoR1 (r = -0.45, P < 0.001) and MoR2 (r = -0.28, P < 0.05).
CONCLUSION: Our results indicate that subcutaneous small artery structure is related to MoR, possibly because an altered vascular structure may amplify BP changes or, vice versa, because a greater MoR may further damage peripheral vasculature.