Abstract
Chronic venous disease (CVD) is a common condition which develops as a result of abnormal
venous blood flow in the lower limb. The disease can present with a wide variety of clinical
manifestations, most commonly in the form of telangiectasias and varicose veins. In its most severe
form, it can present in the form of trophic skin changes and venous ulceration – these cases
comprise the majority of the global healthcare burden associated with CVD. Despite its high
prevalence across society, the current state of funding and resource-provision into research and
patient-care advancements in this field is scarce. As a result, there is currently limited
understanding as to which patients are more likely to develop the more severe and debilitating
forms of venous disease. Although CVD is widely accepted to be the result of progressive valvular
incompetence in the large superficial veins, the involvement of the superficial microvenous
network is less well understood. Previous research by our group has found that venous reflux can
exist in the superficial microvenous network independently of large vein incompetence. From this
it has been proposed that microvenous incompetence could indicate the early signs of advanced
CVD – serving as a prospective marker of disease severity. Historically, imaging of the superficial
microvenous network has presented a number of difficulties – recently our group has found that
microvenous reflux could be visualised with near-infrared fluorescent (NIRF) imaging, in
amputated human limbs (ex vivo). This project aimed to determine whether visualisation of the
microvenous network in lower limbs, using NIRF imaging, differs between patients with chronic
venous disease and healthy controls, in vivo. A study population of 11 individuals was recruited
from a cohort of venous disease patients and healthy community volunteers. The medial calf region
of each participant was imaged, and comparisons were made between the observed patterns of
microvenous reflux in participants with different clinical severities of CVD. Findings from this
investigation indicate that – (1) NIRF imaging can detect microvenous reflux in an in vivo setting;
(2) participants with venous disease can be differentiated from healthy controls by the presence of
microvenous incompetence; (3) more extensive observed microvenous reflux was associated with
a higher clinical severity of venous disease; (4) regions of microvenous incompetence may have
an influence on the location of visible CVD signs. Results from this study add further knowledge
to the understanding of the CVD pathophysiology and may provide evidence towards microvenous
incompetence as a prospective indicator of venous disease severity. NIRF imaging could
potentially be a minimally invasive tool to screen patients at risk of disease progression.