Figure 3a: Kaplan Meyer survival curves to estimate primary patency rate at 12 months for all 25 cases with modified grafts (with cuff) (91.3%) and all 60 cases with unmodified grafts (without cuff)(60.4%). Difference statistically significative : Logrank test p-value 0.007. Each tick marks on curves represents an event i.e, patient death, time of graft occlusion or endovascular o vascular adjunctive procedures.