Skin microcirculation and hypertension: is there a connection?

Abstract

Introduction: Hypertension is an important risk factor for myocardial infarction, stroke, peripheral arterial disease, and chronic kidney disease. The World Health Organization has determined that approximately 1.28 billion adults worldwide have high blood pressure. Its definition has changed over the years, and in 2017 the American College of Cardiology and the American Heart Association have defined blood pressures ≥ 130/80 mmHg as hypertension. Methods: The PubMed database was searched using the MeSH terms sodium, capillary resistance, hypertension, and microvascular rarefaction to identify articles relevant to skin sodium levels, peripheral circulations and vascular rare fraction, and hypertension. Results: Experimental animal and human studies indicate that there are fewer capillaries and arterioles in patients with primary hypertension, and decreased density, also known as rarefaction, increases peripheral resistance. Microvascular density can be estimated noninvasively by methods such as intravital video microscopy in cutaneous regions or in nailfolds. The mechanisms of the reduction in density have been studied and could be used as a parameter when evaluating therapeutic options for patients. The skin provides a reservoir for sodium and can help moderate fluctuations in blood pressure associated with changes in sodium intake. In addition, the skin can modulate fluid volumes in the body through transepidermal water loss. Conclusions: This review discusses microvascular rarefaction, changes in microvasculature structure including the skin capillaries with hypertension, the association between sodium and skin physiology relevant to hypertension, transepidermal water loss, and the vascular effects associated with some antihypertensive medications that help explain their benefit in the prevention of cardiovascular events.