PATHOPHYSIOLOGY OF PERIPHERAL (ORGAN) CIRCULATION AND MICROCIRCULATION: MECHANISMS, DISORDERS, AND CLINICAL IMPLICATIONS

Abstract

The peripheral circulation and its terminal vascular bed — the microcirculation — constitute the functional interface between the cardiovascular system and parenchymal tissues, governing oxygen and nutrient delivery, metabolic waste clearance, and immune cell trafficking. Disruption of microvascular homeostasis underlies the pathogenesis of a broad spectrum of clinical conditions, including septic shock, diabetes mellitus, heart failure, and multi-organ dysfunction syndrome. This review critically examines the structural organization, physiological regulatory mechanisms, and pathophysiological alterations of peripheral and microcirculatory networks, integrating evidence from molecular, cellular, and clinical research published predominantly between 2015 and 2024. Key findings indicate that endothelial dysfunction — characterized by impaired nitric oxide bioavailability, glycocalyx degradation, and pathological leukocyte–endothelium interactions — represents the central mechanistic convergence point across diverse microvascular disease states. Septic microvascular failure is distinguished by heterogeneous perfusion with coexisting hyperperfused and non-perfused capillary units; diabetic microangiopathy involves pericyte loss and basement membrane thickening; and inflammatory microvascular injury is dominated by oxidative stress and inflammatory mediator-driven barrier disruption. Modern diagnostic modalities — including sublingual sidestream darkfield imaging, laser Doppler flowmetry, and circulating endothelial biomarkers — are beginning to translate microcirculatory assessment into the clinical arena. The clinical significance of this synthesis lies in identifying microcirculation as a tractable therapeutic target and in delineating priority areas for future investigation.