Abstract
Chronic Venous Disease (CVD) refers to a wide range of clinical manifestations that can present in the lower limb. It is one of the most common diseases affecting the general adult population, and can vary in clinical severity. More severe forms of the disease contribute to a significant reduction in patient quality of life, and increase the burden placed on the healthcare system. At present, it is not possible to predict whether disease complications will progress in patients with CVD. Development of CVD is linked to incompetence in venous valves, as well as structural changes in the venous wall. Previously it has been shown that venous insufficiency can be prevalent within the microvenous network, even when valves in larger trunk veins showed no signs of venous reflux. It is possible that insufficiency at this microvenous level, could indicate the early stages of more advanced CVD. Near infra-red (NIR) imaging has been proposed as a method of detecting microvasculature within the skin. This would be useful in the context of investigating microvenous reflux, however, the sensitivity of this technique needs to be evaluated. This project aimed to identify whether fluorescence imaging has the potential to visualise microvenous reflux, which has been suggested as a prospective marker of chronic venous disease severity. Seven patients undergoing lower limb amputation for peripheral artery disease consented to have their excised limb examined as part of this study. Post-amputation, the great saphenous vein was cannulated just above the medial malleolus. This access site was used to perform digital subtraction venography and near-infrared fluorescence imaging of the medial calf region. The same site was then used to perfuse the GSV with resin to produce a venous vascular corrosion cast. Imaging modalities were compared to determine concordance in patterns of venous reflux. The results of this study indicate that fluorescence imaging is capable of visualising microvenous reflux ex vivo, where other, methodologically similar, imaging modalities may not. Variable patterns of superficial microvenous reflux, involving incompetent venous valves, were observed in the resin casts obtained. Fluorescence imaging consistently identified regions of microvenous reflux, which corresponded to those seen in resin casts. This differed from venography, where microvenous filling was not typically seen in the matching venograms. The findings from this study may prove to be useful in the context of investigating early stage CVD, prior to the appearance of visible signs of advanced venous disease, such as skin changes. However, further research is required to assess the relevance of these study findings in an in vivo setting.