Relationships between coronary flow vasodilator capacity and small artery remodelling in hypertensive patients.

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Abstract
Arterial hypertension is frequently associated with the presence of structural alterations in small arteries. Moreover, a reduced coronary flow reserve and vasodilator capacity has been observed in essential hypertensive patients, possibly due, at least in part, to microangiopathy of small coronary vessels. The aim of the present study was to evaluate a possible relationship between subcutaneous small artery structure and coronary flow reserve or vasodilator capacity in patients with essential hypertension. A total of 20 patients with mild to moderate essential hypertension were included in the study, and underwent a biopsy of the subcutaneous fat from the gluteal region. Small arteries were dissected and mounted on a micromyograph. The media thickness, the normalized internal diameter and the media:lumen ratio (M/L) were then calculated. In addition, a transesophageal Doppler echocardiographic study, which allows the measurement of coronary flow velocity before and during maximal pharmacological vasodilatation, was performed. Coronary flow reserve (CFR) was measured as the ratio of coronary flow velocity assessed during adenosine infusion and that measured in basal conditions. From blood pressure and coronary flow velocity during adenosine infusion, minimum coronary resistance was calculated. CFR as well as minimum coronary resistance were significantly correlated to both M/L and to normalized internal diameter of subcutaneous small arteries. Our results are consistent with the hypothesis of a generalized remodelling of small arteries in the body, including the coronary circulation; this remodelling may play an important role in the reduction of coronary vasodilator capacity in patients with mild to moderate essential hypertension.