Fem Fem Crossover bypass graft (abbreviated as FFXover in this section)
Content collated from
- Schneider JR. Aortoiliac Disease: Extra-anatomic Bypass. In: Cronenwett JL, Johnston KW, editors. Rutherford’s Vascular Surgery. 7th ed. Philadelphia: Saunders Elsevier; 2010.
Indications for extra-anatomic (as opposed to anatomic) bypass:
1. High cardiac or respiratory risk for more ‘invasive’ operation
2. Hostile anatomy: adhesions, stomas, infection.
Explain the following statement.
In the current (2010) era of vascular surgery, extra-anatomic bypass techniques are likely to comprise an increasing proportion of open surgery procedures for aorto-iliac disease.
The options for aorto-iliac occlusive disease are
- anatomic bypass by open surgery
- extra-anatomic bypass
- endovascular revascularisation.
The advent of endovascular therapy has decreased the overall proportion of open surgical aorto-iliac interventions. Endovascular treatment works better for more localised disease. Such disease occurs more often in the younger population - who, in turn, are the group more likely to have been offered open surgical ‘anatomic’ (such as aorto-femoral) bypass. On the other hand, older patients - often, with more diffuse atherosclerosis, and often also constituting higher surgical-risk candidates - may be less suited for endovascular treatment and may need open surgery. The requirements of this latter group of patients may lead to an increasing proportion of surgical treatment in the current era being of the extra-anatomic bypass variety.
Content credit: Schneider JR. Aortoiliac Disease: Extra-anatomic Bypass. In: Cronenwett JL, Johnston KW, editors. Rutherford’s Vascular Surgery. 7th ed. Philadelphia: Saunders Elsevier; 2010.
Haemodynamics of Fem Fem Xover (abbreviated as FFXover in this section)
“in the absence of flow-limiting lesions in the donor iliac arterial system, one iliac artery can support both legs, at least at rest” (Schneider JR)
Ehrenfeld demonstrated (in an animal model) that the capacity of a healthy iliac artery exceeds the resting flow requirements of both legs.
Multiple studies indicate that iliofemoral bypass (which, of course, is relatively more invasive) offers better patency rates than Fem Fem Xover.
Nowadays, one can elect to optimise iliac artery inflow by endovascular means (if so required) preceding the Fem Fem Xover.
Flanigan described the papaverine test to detect the ability of the donor iliac system for a FFXover to compensate for increased flow requirements. Systemic arterial pressure and donor femoral arterial pressure are both compared before and after the injection of 30 mg of papaverine into the femoral artery. Doppler confirmation of increased flow in the femoral artery following injection is important, to rule out a false-negative due to outflow disease, or due to technical problems with execution of the test. Flanigan labelled a fall in pressure of more than 15% (compared to the systemic pressure) to be an unsatisfactory result.
“...many authors have found that the patency of the superficial femoral artery has no detectable impact on long-term patency (of FFXover)” - all that is required is that at least one outflow artery be relatively healthy (SFA or PFA), just as is the case with patency after aortofemoral bypass. - Schneider JR.
Schneider says he always ensures he can pass a 3.5 mm probe through the toe of the to-be-completed outflow anastomosis, to be satisfied about adequacy of outflow.
He also mentions the weighted average of many studies for the 5 year patency of FFXover to be 66%.
Stone offers duplex surveillance indices for FFXover. PSV (peak systolic velocity) >300 cm/s in the inflow vessel, or a mid-graft PSV of <60 cm/s were found predictive of impending graft thrombosis.
Peculiariities of FFXover in the younger patient:
- A trend towards inverse relationship of patency with decreasing age; the explanation, akin to that seen in aortofemoral bypass, may owe itself to more aggressive atherosclerotic disease in patients who need the intervention at a younger age
- The potential for sexual (erectile) dysfunction with aortofemoral bypass may predispose younger patients to favour a FFXover instead.
Schneider JR: No evidence to choose between dacron (polyester) and ePTFE, or between ePTFE and externally supported PTFE, for a FFXover. There also appears to be no relationship between diameter (whether 6,7,8 or 10 mm) and haemodynamics or patency for FFXover.