**8. Incidence**

414 Aneurysm

According to some, endovascular procedures can be important in the management of critically injured patients, as well as those with chronic FTA [33-43]. Endovascular repair of a peripheral FTA seems attractive because it theoretically results in less morbidity and shorter hospitalization [33]. However, this experience is still limited, especially in young patients. There is also skepticism regarding the use of stents in the popliteal artery. The reason is the mobility of the knee joint. Because of their history of numerous complications, FTAs require prompt treatment. The treatment is simpler if there is not an extended interval between the injury and the operation. Endovascular repair is mostly indicated in locations

Most common false aneurysm belongs to group of anastomotic aneurysms and they present clinical challenges in detection, evaluation, and treatment. The incidence is approximately between 1.4% and 4% [44]. Claytor and associates, in 1956, reported the first case of

Although silk was used as a suture material for anastomosis (prior to 1967), the most frequent cause of FAA was breaking of the suture material [47-54]. Introduction of synthetic polyfilament suture materials has significantly decreased this cause. Also, the prosthesis defects in manufacture have long ceased to be the cause of the FAA. A whole range of arterial wall changes could lead to the formation of an FAA: infection arterial degeneration, aseptic necrosis of the suture line, extensive endarterectomy, and large ''patch'' or anastomosis, according to the Laplace rule [53-63]. A mechanical stress in the anastomotic area was the most important cause from the group of ''other'' factors. Movements in the hip area creating this kind of stress are recognized as the reason for the most frequent occurrence of FAA in the inguinal area after aortobifemoral reconstruction [49,55,62,64,65]. Growth of tissue created between the graft and the inguinal ligament prevents the graft from ''sliding'' over the ligament when a hip movement is performed [49]. For this reason, the FAA often develops after aortofemoral reconstruction but rarely develops after axillofemoral, femorofemoral, or femoropopliteal reconstruction. Szilagyi and colleagues believed this is the reason for the FAAs that manifest later [53]. In his discussion of the Stoney and Albo study [47], Baker suggested that anastomosis in the femoral region must be covered by a mobilized sartorius muscle to decrease stress. Mechanical stress caused by insufficient graft length [50] or configuration of end-to-side anastomosis [47,56,66] and the mechanical stress caused by an extensive mismatch, occurring if the prosthesis is too rigid, are also described. With every pulse wave, the anastomotic part of the artery is dilated at least 10% more than the prosthesis. Given that this difference increases with the size of

anastomotic aneurysm in a patient after prosthetic aortic graft placement [45].

In 1978, Wesolowski outlined these common causes of FAA [46]:

where a surgical approach is not easily attained.

**7. False anastomotic aneurysms (FAA)**

1. Suture material

3. Arterial changes 4. Other factors

2. Prosthesis defects in manufacture

According to the literature, FAAs most often develop in the inguinal area [74-78]. They can develop after the aortofemoral or infrainguinal bypass (figure 13, 14 and 15). They develop in 14 to 44% of inguinal anastomoses [57,63,68,79], although the cumulative risk in clinically significant FAAs is probably less than 10% [80-84]. Inguinal FAA development is clearly a matter of time for the risk increases with the age of the patient and the graft. The literature cites the following frequency of FAA after the aortofemoral bypass operation: 0.4% [85], 1.4% [86], 2% [87], 3.2% [88], 3.3% [89], 3.9% after 17 years of monitoring [53], 4% [90], 4.7% [91], 7% [92], 3.88% [93], and 4.3 [94]%. Cintora and colleagues stated that the FAA incidence in the aortobifemoral position is 4% if a Dacron graft is used and just 1% if a PTFE graft is used, all types taken into account [95]. If the publishing dates are analyzed, the number of FAAs was larger at an early age owing to the poorer quality of the prosthesis and suture material. Data in table 1. show changes in interval of inguinal FAA development through time [96].


**Table 1.** Time Intervals of the Appearance of False Anastomotic Aneurysm

The main reason for this is the improvement in surgical technique and better quality of prosthetic and suture material. Also, it takes longer for the other etiopathogenetic factors, with the exception of the infections, to develop. Some literature data cite the fact that partial section of the inguinal ligament and enlargement of the tunnel in which the prosthesis lies, combined with free omental wrapping of the entire suture line, decrease the incidence of FAA [80].

Aortic FAAs are rare [77,97-99], and with the total number of operations in mind, their incidence of occurrence ranges from 2 to 10% [68-71]. They are believed to be more frequent after emergency procedures. Also, they are much more frequent after end-to-side than after end-to-end anastomosis [77] (figure 16) Owing to the development of surgical procedures, the occurrence of aortic FAAs has decreased to less than 1% [99]. With the lack of symptoms,

it is difficult to diagnose aortic FAA. They are often detected during the evaluation of other abdominal diseases and conditions. Sometimes patients can notice the existence of a pulsatile abdominal mass, back pain, or weight loss [97,98]. Unfortunately, many aortic FAAs present only with acute expansion, rupture, gastrointestinal bleeding, infection, or distal embolism [94,95,97]. They are, in that manner, similar to abdominal aortic aneurysms.

The incidence of anastomotic aneurysm after carotid endarterectomy (with or without patch angioplasty) is approximately 0.3% [100]. They are most commonly associated with prosthetic infection [101].
