Development of vascular substitutes for low-flow peripheral bypass grafting – a review

The development of a low-flow vascular prosthesis is a very topical issue. The authors present a pathway for the development of a prosthesis with optimal properties based on the idea of mimicking the characteristics of a biological model (saphenous vein graft) and programming these properties in the model of the prosthetic substitute. The vascular prosthesis presented consists of three layers – a non-absorbable scaffold representing vascular “media”, and two absorbable collagen layers – pseudointima and pseudoadventitia. The basic methods of physical testing are presented – the single axis stretch test and inflation-extension test, as well as other procedures that affect the final properties. These include collagen curing, antithrombotic treatment of the inner layer and the use of sterilization methods. The designed new graft was successfully im- planted in an ovine model.

Initial experience with a new quantitative assessment tool for fluorescent imaging in peripheral artery disease

Background: Perioperative evaluation in peripheral artery disease (PAD) by common vascular diagnostic tools is limited by open wounds, medial calcinosis or an altered collateral supply of the foot. Indocyanine green fluorescent imaging (ICG-FI) has recently been introduced as an alternative tool, but so far a standardized quantitative assessment of tissue perfusion in vascular surgery has not been performed for this purpose. The aim of this feasibility study was to investigate a new software for quantitative assessment of tissue perfusion in patients with PAD using indocyanine green fluorescent imaging (ICG-FI) before and after peripheral bypass grafting. Patients and methods: Indocyanine green fluorescent imaging was performed in seven patients using the SPY Elite system before and after peripheral bypass grafting for PAD (Rutherford III-VI). Visual and quantitative evaluation of tissue perfusion was assessed in an area of low perfusion (ALP) and high perfusion (AHP), each by three independent investigators. Data assessment was performed offline using a specially customized software package (Institute for Laser Technology, University Ulm, GmbH). Slope of fluorescent intensity (SFI) was measured as time-intensity curves. Values were compared to ankle-brachial index (ABI), slope of oscillation (SOO), and time to peak (TTP) obtained from photoplethysmography (PPG). Results: All measurements before and after surgery were successfully performed, showing that ABI, TTP, and SOO increased significantly compared to preoperative values, all being statistically significant (P < 0.05), except for TTP (p = 0.061). Further, SFI increased significantly in both ALP and AHP (P < 0.05) and correlated considerably with ABI, TTP, and SOO (P < 0.05). Conclusions: In addition to ABI and slope of oscillation (SOO), the ICG-FI technique allows visual assessment in combination with quantitative assessment of tissue perfusion in patients with PAD. Ratios related to different perfusion patterns and SFI seem to be useful tools to reduce factors disturbing ICG-FI measurements.

Abstract 204: Brilliant Blue FCF is an Alternative Vein Marking Dye That Restores Functional Viability in Human Saphenous Vien Graft

Objective The human saphenous vein (HSV) is the most effective conduit for infrainguinal peripheral bypass grafting. Optimal vein graft preparation is critical to vein graft patency. Graft marking using surgical skin markers is detrimental to endothelial and smooth muscle function of the graft. The objective of this study was to evaluate the effect of FD&C Brilliant Blue No. 1 (FCF) as an alternative for vein graft marking. Methods Segments of HSV were collected after typical harvest and graft preparation. The tissues were cut into rings and either left unmarked or marked with FCF (2.6 mM). The functional viability of the rings was determined in a muscle bath. Results Marking with FCF did not impair contractility of the smooth muscle (Figure 1A). Contractility was restored in HSV segments that had no functional contractile responses after harvest and preparation (Figure 1B). To determine the mechanism of this protective effect of FCF, purinergic receptors were activated with BzATP with and without pre-incubation with FCF (50μM) or a purinergic receptor antagonist (oATP, control) and the rise in [Ca 2+ ] i was measured. FCF and oATP reduced the BZATP-evoked rise in [Ca 2+ ] i (Figure 1C), suggesting that the salutary effects of FCF were due to inhibition of a P2X or P2Y receptor. Conclusions FCF is a non-toxic alternative to surgical skin markers that antagonizes purinergic receptors in HSV. FCF restored functional viability to injured vascular smooth muscle. FCF may protect HSV against injury-elicited ‘danger’ signals such as extracellular ATP that is released during injury-induced preparation.

An unusual cause of peripheral artery embolism: Floating thrombus of the thoracic aorta surgically removed

Intraluminal mobile thrombus of the descending aorta are rare disorders. They are at high risk for peripheral embolism and therefore indication for treatment is mandatory. We report on a 54-year-old patient with peripheral arterial embolization who was treated by surgical thrombus removement by thoracotomy and staged peripheral bypass grafting. New diagnostic tools are presented, therapy and prognosis are discussed.