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Background Traditionally, multilevel arterial disease has been treated with an inflow procedure only but simultaneous multilevel bypass graft procedures have been attempted. However, these procedures are potentially high risk. We report our single-center experience of performing multilevel bypass grafts over the last 15 years. Methods We retrospectively identified patients undergoing simultaneous aortoiliac and infrainguinal bypasses between January 1996 and January 2011 at a single district general hospital. Results There were 32 multilevel procedures performed. Indication for surgery was acute ischemia in 10 (31.3%), critical ischemia without tissue loss in 10 (31.3%), with tissue loss in 10 (31.3%), and claudication in 2 (6.3%). In 23 (71.9%) cases inflow was restored using a direct iliofemoral or aortofemoral reconstruction. In the remaining 9 (28.1%), an extra-anatomic bypass was constructed. Two (6.3%) patients died within 30 days of surgery. Twenty-nine (90.6%) patients survived to discharge. Twenty-eight patients (87.5%) were alive 1 year after surgery. Limb salvage was 96.9%, 85.7%, and 75.9% at 30 days, 1 year, and 5 years, respectively. Twelve (37.5%) patients required a total of 19 further ipsilateral vascular procedures. Conclusions Our results demonstrate that multilevel bypass procedures can be performed with good long-term outcomes and acceptable mortality, in what is typically a high-risk group with extensive comorbidities. In patients with severe critical limb ischaemia and tissue loss, who have a combination of aortoiliac and infrainguinal disease, there are significant benefits to a primary multilevel grafting procedure.

Protein-membrane interactions are a vital mechanism of propagating signals both across the membrane and between cells. One method of signal propagation is the formation of lipid microdomains that allow the preferential clustering of specific lipid types and proteins. To address this type of signal propagation, we investigated how lipid microdomains form in response to annexin binding to model membranes. Annexins bind to negatively charged (e.g., phosphatidylserine [PS]) membranes in a calcium-dependent manner and lead to the formation of PS-enriched microdomains in supported planar bilayers. Two distinct mechanisms of signal propagation via protein-lipid binding are addressed. First, we hypothesize that proteins can transmit binding information via the ordering of the lipid acyl chains upon binding. Alternatively, we predict that when a protein binds a specific lipid preferentially, protein-protein interactions are enhanced on a membrane surface. The role of lipid acyl chain ordering and protein-protein interactions as distinct mechanisms of signal propagation through lipid binding will be illustrated.