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OBJECTIVES: According to guidelines, the autogenous saphenous vein (ASV) is the preferred conduit for femoropopliteal bypass surgery in all patients with peripheral artery disease. However, in contrast to patients with critical limb ischemia (CLI), patients with intermittent claudication (IC) only, tend to have milder disease, and thus a prosthetic graft may be as good as a vein conduit. The objective of this study was to compare patency rates of the ASV and a prosthetic graft in femoropopliteal bypass surgery in patients with IC. METHODS: A systematic literature search was performed in the PubMed, Embase, and Cochrane databases to identify randomized controlled trials comparing prosthetic graft versus ASV in patients with IC. Articles with a mixed IC and CLI study population were included if more than 50% of the study cohort was treated for IC. Primary analysis was performed on IC patients only. Secondary analysis was performed on the mixed group. The primary endpoint was short- and long-term patency and secondary endpoints were complications, limb salvage, and mortality. RESULTS: In total, six studies with 524 patients were included. Only two studies reported solely on patients with IC. All these patients underwent above-the-knee bypasses and average patency rates at one and 5 years were 88% and 76% vs 81% and 68% in the ASV and the PTFE groups, respectively. One and five-year patency was not statistically different between the groups (OR 5.21; 95% CI 0.60-45.36 and OR 2.10; 95% CI 0.88-5.01). In a mixed population of patients with IC and CLI (84% IC patients), 1 year patency was comparable (OR 1.40; 95% CI 0.87-2.25). However, after a follow-up of over 3 years, this mixed group had significantly higher patency rates in favour of the ASV (OR 2.06; 95 % CI 1.30-3.26). Complication and amputation rates were comparable in both groups. CONCLUSIONS: Limited data are available for patients receiving above-the-knee femoropopliteal bypass for intermittent claudication. The ASV remains the conduit of choice for femoropopliteal bypass surgery. However, the prosthetic conduit seems a feasible alternative for patients with intermittent claudication in whom the ASV is not present or unsuitable.
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Nitrous oxide (N2O) is increasingly used as a recreational drug, and is presumed relatively safe and innocent. The risks for neurological complications are often known, however the risks of serious thromboembolic events are not. We describe three cases of acute thromboembolic events resulting in serious cardiovascular complications after N2O abuse: one case of myocardial infarction that resulted in a reduced ejection fraction, one case of peripheral arterial occlusion that led to limb amputation and one case of pulmonary embolism that resulted in hemodynamic instability requiring extracorporeal membrane oxygenation (ECMO) and surgical removal. All patients were young adults with a low cardiovascular risk profile. N2O inactivates vitamin B12, leading to vitamin B12 deficiency and subsequent to hyperhomocysteinemia, which is associated with the formation of fibrinolysis-resistant blood thrombi. In conclusion, we contest the safety and innocence of recreational N2O (ab)use. Our three cases illustrate that, next to previously described neurological complications, the use of nitrous oxide is associated with thromboembolic cardiovascular complications, presumably mediated by hyperhomocysteinemia.