pressure on adjacent structures, such as the femoral nerve. Complications may be local or distal. The enlarging aneurysm may occlude the underlying vessel, causing distal ischaemia.Emboliassociatedwithflowdisruptionmaybepropagateddistally.Aneurysm rupture represents the greatest worry but is relatively rare. Complications are related to aneurysm size. Therefore, conservative management may be undertaken if the aneurysm is small and easily accessible, and demonstrates no evidence of progressive enlargement or symptoms. Aneurysms less than 2 cm in diameter can be observed safely.1 Above this size, the incidence of complications rises and intervention should be considered. However, the medical state of the patient may necessitate selected aneurysms larger than 2 cm being managed conservatively by watchful waiting.

False aneurysms caused iatrogenically following direct arterial puncture must be differentiatedfromanastomoticaneurysmsbecausetheirtreatmentdifferssubstantially.False aneurysms following sterile arterial puncture may be treated by arterial compression under duplex imaging.11 More recently, injection of thrombin into these false aneurysms has been shown to be safe and effective, even in anticoagulated patients.12 This technique is not suitable for anastomotic aneurysms. Other radiological techniques may be used selectively for false aneurysms in inaccessible positions, such as the renal or subclavian arteries, where coil embolization may be used to occlude the feeding vessel.13 Again, this is rarely suitable for anastomotic aneurysms. Occasionally, endovascular treatment with a covered stent can beemployedacrossananastomoticaneurysmtoproduceaneurysmsacthrombosis14, 15 and to maintain normal distal flow. This technique is particularly valuable for intra-abdominal aortoiliac anastomotic aneurysms, where reoperation carries substantial risk. It is important that endovascular techniques are not used in situations where there is any risk that the false aneurysm is due to infection. The most common site for anastomotic aneurysm is the groin, where non-operative techniques have not been found to be effective. The groin is also easily accessible for surgery, so direct operation is the usual intervention in this situation. [Q3: A, B, C, D] [Q4: A, C, D, E, B]

10.3 

Treatment for Anastomotic Aneurysms

Surgical repair should be undertaken in fit patients with large or symptomatic anastomotic aneurysms. Local repair is usually possible in non-infected aneurysms, although graft replacement may be necessary. If infection is the cause of the aneurysm, then more extensive repairs with ligation and remote bypass or replacement of the entire initial graft may be needed.16

Anastomotic aneurysms usually occur in arteriopathic patients. Careful preoperative planning is needed to make the patient as fit as possible. General anesthesia is needed to allow adequate exposure, and the surgery is carried out under antibiotic and heparin cover. Once vascular control above and below the aneurysm has been obtained with minimal dissection, the aneurysm should be opened, along with the entire abnormal artery. Occlusion balloon catheters are often helpful in obtaining vascular control in this situation. The false aneurysm

isusuallyresectedandtheendsofthegraftandarteryfreshenedforreanastomosis.Interposition grafting is likely to be needed to ensure that the new anastomosis is created without tension. Autologous saphenous vein is the graft of choice, although often polytetrafluoroethylene (PTFE)orDacronmaybebetterforsizematching.[Q5:A,C,E]Retroperitonealanastomotic aneurysms present more of a challenge. Proximal aortic anastomotic aneurysms may require supracoeliac clamping or balloon occlusion catheters.17 Aneurysms associated with the distal portion of an aortoiliac graft may present late and catastrophically, illustrating the potential importance of monitoring these grafts for a prolonged period.18 As previously stated, and endovascular approach is used increasingly in this situation.

a

b

Fig. 10.3  (a) This man presented with sudden pain in the right groin. A false aneurysm of a previous axillobifemoral graft was diagnosed on ultrasound imaging. Note the inflammatory nature of the lump suggesting infection.

(b) At operation the hood of the graft had separated completely from the artery. There was no sign of sepsis, and all bacterial cultures were negative

10.4 

Infection in Anastomotic Aneurysms

Some 80% of anastomotic aneurysms occur in the groin, and they have the highest incidence of infection as their primary cause; approximately 30% contain pathogenic bacteria. A high level of clinical suspicion of infection must be maintained, and Gram staining of all clots and removed graft should be carried out as a matter of routine. Perioperative antibiotics should be continued until results are available (Fig. 10.3).

The diagnosis of infection is usually obvious if the graft is surrounded by pus. If the graft is frankly infected, it should be excised completely with an extra-anastomotic bypass to restore the distal circulation with prolonged, high-dose antibiotic cover. An obturator bypass may be used for an infected femoral false aneurysm, or a femoral crossover with saphenous vein. Aortic stump oversewing and axillobifemoral grafting can treat the (fortunately rare) infected aortic anastomotic aneurysm. Morbidity and mortality rates are high. Grafts with a more indolent level of infection that becomes apparent only after microbiological investigation may be treated less radically. It is safest to assume that all femoral anastomotic aneurysms are contaminated. If prosthetic material is needed for repair, then measures used to reduce the chance of reinfection include the use of a rifampi- cin-soaked, gelatin-coated Dacron graft and gentamicin beads laid in close proximity. The reinfection rate after such procedures is 10%.19

10.5  Outcome

Outcome depends on the initial site of the aneurysm and any confounding factors.20 As the most common site for anastomotic aneurysms, the femoral artery has one of the highest rates of successful outcome. About 90% of surgical procedures are successful, and those that recur still have a 90% success rate from a second or subsequent operation. In comparison, anastomotic aneurysms that are intra-abdominal have a high complication rate when repaired surgically. A small anastomotic aneurysm in a superficial position can be monitored by ultrasound or by repeated examination by a clinician or the motivated patient. The success rate of operation at these sites is good.21 Retroperitoneal aneurysms require longterm ultrasound follow-up. [Q6: F, T, F, T, F] If possible, minimally invasive techniques should be used for repair to avoid the high morbidity and mortality associated with surgery (providing infection is not present). In patients fit for surgery, excision and graft interposition has excellent long-term results.

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