Arteriovenous Anastomoses as a Dynamic System of Blood Flow Redistribution: Physiological Shunt, Vascular Resistance, and Role in Arterial Hypertension

Arteriovenous anastomoses (AVAs) are specialized vascular connections that directly link the arterial and venous circulation and allow blood to bypass the capillary network. This article considers AVAs not only as components of thermoregulation but also as dynamic low-resistance vascular pathways with an adjustable lumen and resistance. A fundamental distinction between AVAs and collateral vessels is emphasized: collaterals preserve tissue perfusion, whereas AVAs alter the route of blood flow through arteriovenous shunting. The mechanisms of neural and muscular AVA regulation, their contribution to peripheral hemodynamics, and their interaction with arterioles are examined. Evidence from central arteriovenous connections capable of reducing systemic vascular resistance and arterial pressure is interpreted as support for a general hemodynamic principle rather than direct proof of an equivalent effect of physiological AVAs. A hypothesis is proposed that the aggregate functional state of the physiological AVA system may contribute to peripheral vascular resistance regulation and to the development and maintenance of arterial hypertension. The potential of AVAs as an additional pharmacological target in vascular regulation is discussed.