Alterations in capillary morphology are found in mild blood pressure elevation

Remodeling of small resistance arteries is an early sign of target organ damage in hypertension. Peripheral capillary morphology abnormalities in hypertension are not well studied. The study objective was to determine whether altered capillary morphology is associated with SBP, DBP, or both in individuals without and with mild blood pressure elevation (SBP = 130-160 mmHg). Another objective was to determine whether capillary morphology is associated with minimum forearm vascular resistance, a measure of altered resistance artery structure.

Participants included 115 nonpregnant, nondiabetic individuals 23-55 years of age. A five-component morphology score (distribution, tone, configuration, hypertrophy, and extravasates) was developed to describe fingernail bed capillaries visualized using venous congestion in digital photomicrographs. Multiple linear regression models adjusted for age, sex, race, tobacco use, hyperglycemia, dyslipidemia, and renal function were used to analyze the relationship between SBP, DBP, and minimum forearm vascular resistance with the morphology score.

The total morphology score was significantly associated with SBP and DBP as well as minimum forearm vascular resistance (P < 0.005 for all). Among the five individual morphology score components, hypertrophy was significantly associated with SBP and DBP (P = 0.002 and 0.001, respectively), whereas extravasates were significantly associated with SBP only (P = 0.002).

A five-component capillary morphology score is associated with SBP, DBP, and altered resistance artery structure in individuals with and without mild blood pressure elevation. These observations suggest that target organ damage at the level of the microcirculation can be detected using capillary morphology.