Access Sites to Vascular System for Endovascular Abdominal Aortic Aneurysms Repair

The authors describe their experience with access sites for endovascular abdominal aortic aneurysm repair in a group of 165 patients treated over a 10-year period.


INTRODUCTION
The ability to reliably gain access to the vascular system is fundamental to the performance of all endovascular procedures, especially those related to endovascular abdominal aortic aneurysm repair (EVAR) 1 .At present EVAR mostly requires open surgical access owing to the large diameter of the introducing device.Incision of the common femoral artery (CFA) surgically exposed in the groin is the most widely used access site for EVAR [2][3][4] .Narrow, stenotic and tortuous femoral or iliac arteries are responsible for EVAR access problems.They may lead to introducing device fracture or jamming and its subsequent withdrawal may lead to iliac artery damage/rupture [5][6] .A standard access procedure is thus not possible at all or unsuccessful with high risk of technical complications and primary treatment failure 1,7 .In order to overcome some of these access problems, various additional maneuvers can and should be used to facilitate or improve the access [8][9][10][11][12][13] .Procedures performed for EVAR access creation and its closure and access related complications in our group of patients are evaluated in this presentation.

Standard access procedure
One or both CFA (according to stentgraft configuration) are surgically exposed in the groin by vertical or oblique skin incision.A 7-8F sheath for angiography catheter and guidewire are first introduced via a CFA anterior wall puncture and subsequently through an arteriotomy (transverse, V-type and vertical) and iliac arteries (IA) the introducing device with the stentgraft is inserted in the aorta using a stiff wire 1,10,14 (Fig. 1).

Additional maneuvers
Additional maneuvers performed intraoperatively for gaining access to the aneurysm are classified as planned and unplanned procedures.Planned procedures are part of a preformulated operative strategy.Unplanned procedures are necessary for the management of unintended complications 10,13 .

Endarterectomy
Direct surgical endarterectomy is performed for common femoral artery (CFA) and iliac-femoral border atherosclerotic (AS) stenotic access problems.The management of these problems in the external iliac artery (EIA) or in the common iliac artery (CIA) consists primarily of baloon dilatation (PTA), usually with stent employment.Indirect endarterectomy using a Fogarty wire catheter (modified Vollmar desobliteration) may be applied as the next step.

Bimanual introduction
It is possible to hold the iliac artery with the whole hand retroperitoneally after the inguinal ligament lifting (ligament incision is mostly necessary) and the introducing device can be inserted by force under the digital-manual EIA control in case of a stenotic and rigid artery.

Pull-down maneuver (digital stretching).
The maneuver involves the dissection of the CFA and EIA, lifting of the inguinal ligament, and using blunt dissection to reach the iliac bifurcation from the groin.When the arteries are free, a gentle pull on the artery allows the extensive tortuous artery to straighten, thus enabling the introduction of the stentgraft 9 (Fig. 2).EIA surgical shortening via retroperitoenal approach is another option 15 .

Alternative access
The alternative approach refers to vascular access created above the inguinal ligament in case the CFA or/ and EIA are too unfavourable to permit safe device insertion.The stentgraft can be introduced directly, or more typically, via a vascular prosthesis sutured end to side of the CIA or aorta retroperitoneally exposed via a lower quadrant abdominal pararectal incision (Fig. 3, 4).The prosthesis is used either as a temporary conduit (dacron tube prosthesis of adequate diameter to the stentgraft introducer) for the introduction itself or it is subsequently left in place as an iliac/aorto-femoral homolateral or crossover bypass (ePTFE prosthesis), thus solving not only access to the aneurysm but also the AS stenoses in the iliac arteries 8,[11][12] .

Access closure
Primary closure with 5.0 monofilament sutures (running or interrupted) in case of severe AS-free CFA is possible.
Sometimes CFA is so diseased and/or damaged after the introduction that a CFA endarterectomy with patch plastic or even its excision and short prosthesis interposition is required (Fig. 5).The inflow anastomosis of the femoral-femoral bypass in aortouniiliac stentgraft practically covers up the vascular access.

Access site complications
Access site complications are presented as specific and non-specific.Specific complications are connected with the introducing procedure itself; CFA/IA perforation, disection which require immediate endovascular or surgical repair or even conversion to open repair.Non-specific complications are connected with the operating wound; haematoma (in groin or in retroperitoneal pelvic space), false aneurysm (especially after percutaneous procedure), lymph fistula and wound infection.These complications can be observed, spontanously solved and only occasionally do they require open surgical repair 10,15 .

PATIENTS, RESULTS
Between April 1996 and April 2005, 170 stentgrafts were introduced in 168 patients with asymptomatic AAA for standard accepted indications.One type of stentgraft system: Ella (ELLA CS, Hradec Králové, Czech Republic) was used for AAA exclusion in all patients.Stentgraft configuration included 3 aortic tubes, 142 bifurcated (bimodular) grafts, and 25 aortouniiliac grafts [20][21][22] .These stentgrafts required a total of 312 vascular accesses.All the stentgraft introducing devices were successfully inserted and there was no failed vascular access related conversion to open surgery in our patients.CFA (n = 300) was used in 96 % of accesses.Standard access procedure (n = 286) was used in 95.3 %.CFA was exposed by vertical incision in all patients and two types of CFA arteriotomies were used; transverse (n = 65; 22.7 % ) and vertical (n = 221; 77.3 %).Percutanous access (n = 14) was used in 4.7 %.In 8 patients the whole bifurcated stentgraft (n = 6) or the contralateral limb of the bifurcated stentgraft (n = 2) were percutaneously introduced.Ilio-femoral bypass (n = 12) was used in 4 % of the accesses (Table 1).Patients with temporary aortic conduits (n = 3) created for the implantation of an aortic tube stentgraft in cases of thoracic aorta aneurysm (n = 1) and type IV thoracoabdominal aneurysm (n = 2) were not statistically included in this group of patients [11][12] (Fig. 4).The additional maneuvers and procedures (n = 54) were successfully used for iliac artery tortuosity and occlusions solution in 17.2 % (Table 2).There was no increased morbidity or mortality connected with the additional retroperitoneal maneuvers.The CFA was surgically closed in 56 % of accesses using direct suture, and additional surgical corrections were used in 36 % of accesses (Table 3).Local access site complications occured in 29 (9.4 %) accesses (Table 4).
There were no vascular access complications requiring open surgical conversion and no severe groin wound and lower extremity threatening complications.All of the IA traumata were immediately solved successfully.Both EIA perforations and two of the EIA dissections were surgically solved by retroperitoneal iliac-femoral bypass (n = 4).Stentgraft extension (n = 1) and indirect surgical endarterectomy (n = 2) were used in the other dissection cases.Most wound complications were spontaneously resolved, but early surgical haemathoma evacuation was also required (n = 3), and subcutaneous space due to lymph fistula was resutured (n = 2).In cases of wound dehiscence based on wound haemathoma infection, operative revison (debridement) was required.All superficial wound infections were resolved with antibiotics only.Lower extremity ischemic complications due to periphery embolisation were not observed.
There were no complications where the retroperitoneal approach was used, and there were no problems (herniation) related to ligament incision.In percutaneously performed accesses, the 8 and 10F Prostar devices (Perclose Inc, Vascular Abott Devices, Redwood City, USA) were used for CFA closure.Success was achieved in 11 cases (79 %) with only 3 closure failures which necessitated immediate (n = 2) and elective (n = 1) conversion to open groin incision and surgical CFA suture 19 .Vascular access for EVAR depends on vascular access site (CFA and IA) anatomy and pathology for the first and on introducing device diameters corresponding with the stentgraft configuration based on AAA morphology for the second.
Thorough anatomical evaluation of the AAA as well as of the access arteries is crucial to ascertain patient suitability for EVAR and to avoid access failure 6,23 .Because of the large diameter of the current aortic stentgraft introducing devices, a surgicaly created controlled entry into the artery lumen is mostly necessary to avoid access complications.All incisions in the groin region, especially in obese patients, have a high risk of wound infection or lymph leak complications, with a lower rate reported in oblique type of incisions.We preferred classical vertical incision for CFA exposure with acceptable local wound complications rate.The transverse or V-type of arteriotomy is only possible in large or soft and AS-free CFA.The V-type incision has the advantage of providing a "ramp" on which the introducing device slides.
In CFA significantly diseased by atherosclerosis, verical arteriotomy is mandatory.This allows for a better examination of the lumen and for careful arteriotomy closure 1 .We preferred vertical arteriotomy and the transverse one was mostly for the contralateral bifurcated stentgraft limb (16F devices).From the access sites point of view, the current EVAR morphological indication criteria include significant stenosis and tortuosity-free IA of diameter no less than 8 mm or 6-8 mm without calcifications at least on one side 1,[5][6][7] .The dimensions of the introducing device, i.e. its diameter, depend on the construction, type and size (length and diameter) of the stentgraft.Current technologies of stentgraft construction do not allow the use of introducing devices with an outer diameter lower than 18-24F for the body of the bifurcated stentgraft and 16-18F for the iliac segments 23 .When using introducing devices of a smaller diameter than that corresponding with that required by the stentgraft, there is a danger of stentgraft deformation (shortening) during its extension.The preferred type of AAA exclusion -bifurcated stentgraft -requires an iliac artery without the presence of significant stenoses and tortuosity on either side.In case of bimodular bifurcated stentgraft, the side of components introduction is selected so that the artery diameter corresponds with that of the introducing device.
For stentgraft body introduction, we select the side with an artery with a larger and direct diameter and less AS changes and calcifications.The introduction of the contralateral iliac limb is mostly problem-free [3][4] .In case of unilateral CFA and IA access pathology, the use of aortouniiliac stentgraft introduced from the opposite side can be the best solution 24 .
The introducing device is of extensively large diameter (24F and more) in case of unibody bifurcated stentgraft configuration or in case when a stentgraft of a high length and large diameter (according to AAA) is needed and therefore alternative access is mostly required.Smaller-diameter introducing devices with a connical top can overcome the problem of narrow IA, but tortuosity remains a problem in providing access through these arteries.
The use of extra-stiff guidewire (from left brachial artery to the preferred femoral artery ) is the basic method to extend the artery in case of tortuosity, and when no heavy circumferential calcification is present, the IA is capable of considerable mobility.All the additional maneuvers were successful when used in our patients.When the additional maneuvers are not primarily possible or if they have failed, an alternative access is necessary.Iliac-femoral bypass for access is the most frequent of the additional vascular surgical procedures performed in EVAR 13 .All the retroperitoneal alternative accesses are connected with a slightly higher invasivity and, in case of the prosthesis use, with a higher blood loss in filling the prosthesis in contrast to classical transfemoral access, but hemodynamically is the less stressful procedure and it remains acceptable.We also created a bilateral iliac-femoral bypass for bifurcated stentgraft insertion when necessary (n = 2).We generally used a 22-24F introducing device for the main body of the bifurcated stentgraft and 16-18F for the contralateral limb.It is true that these diameters also depend on the type of stentgtraft system used.
We used the Ella stentgrafts, which are of rugged construction and are loaded into the large diameter introducing device, which resulted in the use of alternative access in the more problematic access cases.On the other hand, the Ella introducing device is sufficiently flexible and facilitates reliable introduction.We can confirm this based on the results with 66 % tortuous and 32 % stenosed IA access sites in our group of patients.The advantage of the rugged Ella stentgrafts design is the stentgraft stability and this is reflected in the long-term results [20][21][22]25 . The ethod of CFA arteriotomy surgical closure corresponds with the type of incision and AS changes (stenosis/aneurysm) of this site 1 .In our group of patients the transverse arteriotomy was closed using direct suture in 69 % and the vertical one in 52 %. 98 % of the complicated accesss closures were performed in AS stenoses, with CFA AS aneurysms accounting for 2 %, and the closures were mostly on the side of the bifurcated stentgraft body and/or when an introducing device with a diameter of 22-24 F was used.The rate of vascular access complications increases with narrow iliac artery diameter or large introducing system diameter 26 .Iliac artery diameters below 7 mm are associated with an increased incidence of complications 27 .Unfortunately, iliac artery rupture diagnosis is mostly imposssible before the introducing system withdrawal, and subsequent endovascular solution using stentgraft insertion is problematic 28 .Surgical repair with prosthesis interposition therefore seems to be the best option, as it was in our two cases of EIA trauma.Access failure is becoming the most common cause of primary conversion to open surgical repair 29 . Al endovascular and surgical procedures have to be attempted to overcome the access problems before the decision for conversion to open surgery is made.To reduce the risk of access complications in case of too tortuous or stenotic iliac arteries (especially in the presence of circumferential calcifications) and/or in need of the large diameter introducing devices with repetitive forceful introduction, the alternative access as an easier, safer and more feasible vascular access option is primarily indicated with greater likelihood of success 30 .In our patients, iliac-femoral bypasss was used as a primary planned alternative access, and in three patients with EIA rupture it was used as unplanned.The 24F introducing device was used in each case when the iliac-femoral bypass was required.Although open surgical access is the most common successful procedure for EVAR, there is a tendency to perform it completely percunateously because this is the least invasive technique 1 .The condition for complete percutaneous procedure without access artery suture, 12F introducing-delivery device diameter, is impossible given the current state of stentgraft construction.Therefore, the artery closure problem was solved by percutaneous artery suture devolopment.However, current percutanous suture devices, especially in obese patients with scarred groins and calcificated iliac arteries, are not safely feasible and percutaneous EVAR still often remains unreliable [16][17][18] .All our percutanous closure failures were in obese patients (false femoral aneurysm developed in one) and calcified CFA 19 .In current situation, it seems more effective to only use the percutaneous access for the introduction of the contralateral limb of the bifurcated stentgraft.Extreme morphological EVAR (less stringent anatomical criteria) indication may be used in eldery, high risk patients with large AAA.Open surgical access facilitates better and more rapid recognition and solution of problems when they occur.Under these circumstances, the risk of the procedure is acceptable.EVAR rejection or primary surgical conversion due to failed standard access procedure is thus less common and is the last option.New technological developement may lead to new, more flexible stentgraft designs with reducing the required diameter of the introducing systems.This will be a remarkable progress towards non-limited EVAR, especially in terms of the percutaneous one, in the future and towards reduced incidence of access limitations and complications.

Fig. 1 .
Fig. 1.Classical vascular access for EVAR.A: Drawing of the initial part: stentgraft system introduction.B: Peroperative view.Surgically prepared access (groin incisions) to CFA (with sheaths in arteriotomies) on both sides.C: Peroperative view.Stentgraft system introduced through the CFA arteriotomy on the left.D: Peroperative view.The EVAR procedure is finished, CFA arteriotomies are closed by direct suture.

Fig. 2 .
Fig. 2. Pull down maneuver.A: DSA shows too tortuous EIA on the right side B: Drawing of straightening EIA by pull C: Peroperative view of too tortuous EIA from the groin access