Microcirculation on a Large Scale: Techniques, Tactics and Relevance of Studying the Microcirculation in Larger Population Samples

Abstract

The role of microcirculatory dysfunction is increasingly being recognized in the etiopathogenesis of cardiovascular disease. Whilst the importance of detailed mechanistic studies to determine the exact nature of these disturbances is without question, it was large-scale population-based studies that first identified the associations between deranged microvascular perfusion, autoregulation or structure, and subsequent target organ damage. This is the subject of considerable studies to establish whether there is a causal effect in either direction, or simply represents shared risk factors, although it is most likely to be a complex combination of bidirectional interactions. The techniques for investigating microcirculatory function have evolved almost exponentially over the last 75 years: So too have the strategies for investigation. Current epidemiological studies are focusing on attempting to untangle the inter-relationship between risk factors and pathological mechanisms to attempt to determine whether these represent therapeutic targets or simple markers of unmeasured risk. We plan to review the techniques used for these population-based studies, the advances made, and the clinical implications derived.

The Human Microcirculation

“…Third, these techniques are confounded by local neurohumoral influences, circulating substances, and paracrine or mechanical impact from underlying parenchymal cells. Moreover, most techniques require careful training and are costly, making it difficult to include measurements of microcirculatory function in large populations studies 67 . More recently three non-invasive methods have been validated to assess microvascular flow.…”

Phenotyping the Microcirculation

“…3,21,22 Hypertensive retinopathy was first described in the 19th century and has been used since then in the diagnosis of the severity of hypertensioninduced target organ damage. However, the classic assessment of retinopathy was descriptive and gave no quantitative or mechanistic data on the microcirculatory dysfunction.…”

“…Large-scale epidemiological studies in the last 2 decades have identified the associations among deranged microvascular perfusion, structure, target organ damage, and subsequent cardiovascular disease. 3 Major technological developments now allow study of the microcirculation both in mechanistic and epidemiological studies. The purpose of this Brief Review is to provide a critical appraisal of these developments and their particular impact on hypertension research.…”

Microcirculatory Marker for the Prediction of Renal End Points

“…These data strengthen the possibility of using retinal imaging as a clinical tool for diagnosing microvascular disease. 42 Finally, narrow arterioles had no effect on all-cause mortality. All reported deaths were similarly distributed between the groups.…”