Acs0613 Surgical Treatment Of The Infected Aortic Graft

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  • 1. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 13 Surgical Treatment of the Infected Aortic Graft — 1 13 SURGICAL TREATMENT OF THE INFECTED AORTIC GRAFT Victor J. D’Addio, M.D., F.A.C.S., and G. Patrick Clagett, M.D., F.A.C.S. In dealing with an infected aortic graft, the primary goal of treat- mortality was associated with this method of treatment.2 In addi- ment is to save life and limb. This goal is best accomplished by tion, many survivors experience significant problems, including eradicating all infected graft material and maintaining adequate early or late allograft rupture and late aortic graft dilation.3 circulation with appropriate vascular reconstruction. Secondary Reinfection of allografts may also occur and usually proves fatal goals are to minimize morbidity, to restore normal function, and to when it does. Complications may be reduced by using cryopre- maintain long-term function without the need for repeated inter- served allografts instead of fresh ones, but at present, the data are vention or amputation. insufficient to determine whether one type of allograft is clearly Before definitive reconstruction, all infected graft material must superior to the other overall. Currently, aortic allografts are avail- be debrided, along with any grossly infected vascular tissue and able in the United States only on a limited basis; accordingly, this surrounding soft tissue. Once debridement is complete, there are technique is not a useful option in emergency situations. several options for reconstruction, including (1) extra-anatomic ANTIBIOTIC-TREATED PROSTHETIC GRAFT bypass, (2) use of an arterial allograft, (3) placement of vascular prostheses treated with or soaked in antibiotic solutions, and (4) Use of antibiotic-treated prosthetic graft material for recon- in situ replacement with a femoral-popliteal vein (FPV) graft.The struction has the advantage of permitting an expeditious recon- choice among these options is made on the basis of the specific struction that leaves no aortic stump.2,4-8 However, the reinfection clinical situation present. The primary focus of the technical rate is high and unpredictable, and patients must undergo lifelong description in this chapter, however, will be on the fourth option antibiotic therapy. Typically, the new prosthetic graft is soaked in [see Operative Technique, below]. rifampin, 60 mg/ml, for 15 minutes before implantation.6,7 IN SITU AUTOGENOUS RECONSTRUCTION Choice of Procedure Dissatisfaction with the long-term patency of extra-anatomic bypass led to the development of in situ autogenous venous recon- EXTRA-ANATOMIC BYPASS struction.9-11 Early reconstructive attempts that made use of Extra-anatomic bypass, usually performed as an axillobifemoral greater saphenous vein grafts proved unsuccessful because the bypass [see Figure 1 and 6:12 Aortoiliac Reconstruction], is a good small caliber of the venous conduit resulted in low patency rates. option for treatment of an infected aortic graft when groin infec- Subsequent attempts that made use of larger-caliber FPV grafts, tion is absent and lower-extremity runoff is good. The primary however, proved highly successful. advantages of extra-anatomic bypass are that it minimizes lower- FPV grafts have excellent long-term patency and are resistant extremity ischemic time and that it is less of a physiologic insult to reinfection. In addition, they are ideal conduits for patients with than an aorta-based bypass procedure (mainly because it is typi- extensive multilevel occlusive disease, in whom venous grafts the- cally done in a staged fashion). The primary disadvantages are oretically would have better patency than prosthetic grafts. (An that long-term patency is poor and that there is a significant risk analogy would be the superior durability of venous grafts for of reinfection. In addition, if groin infection is present, the bypass femoropopliteal bypass in comparison with prosthetic grafts.) The is compromised even further by the need to use vessels such as the 5-year patency rates for aortoiliac/aortofemoral reconstructions profunda femoris artery or the popliteal artery for distal targets. using FPV grafts range from 85% to 100%.11,12 Long-term ampu- Bilateral axillofemoral bypasses are often required in this situation. tation rates are correspondingly low. Because of these factors, the durability of an extra-anatomic bypass The primary disadvantage of reconstruction with FPV grafts is may be limited despite aggressive antithrombotic treatment. that the procedure is time consuming and technically demanding. Extra-anatomic bypasses are plagued by sudden thrombotic In our experience, the mean operating time is about 8 hours.The occlusion, and amputation rates are high. In one large series, one lower-extremity ischemic time is longer than that in patients third of patients required a major amputation during long-term undergoing extra-anatomic bypass, but it can be minimized by follow-up.1 Reinfection also is a major concern when prosthetic sequencing the operation so as to shorten cross-clamp time and grafts are employed in patients with ongoing infection: it occurs in by using a two-team approach. An additional disadvantage of 10% to 20% of such patients and often proves lethal. A final major using FPV grafts is the associated short-term venous morbidity. concern in patients who undergo excision of an infected aortic Approximately 20% of patients who undergo FPV harvesting will graft and extra-anatomic bypass is the possibility of blowout of the require fasciotomy, typically performed at the time of the harvest. aortic stump.This is an infrequent occurrence (incidence < 10%) The fasciotomy rate is highest in patients who undergo concur- but one that is typically fatal. rent greater saphenous vein harvesting and in those who have severe lower-extremity ischemia (ankle-brachial index [ABI] AORTIC ALLOGRAFT < 0.4).13 Long-term venous morbidity appears to be low, with no In situ aortic allografting has been employed to treat aortic graft known cases of venous ulceration or venous claudication.14 Mild infections, with somewhat mixed results. In one report, a 20% to moderate chronic edema develops in approximately 30% of
  • 2. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 13 Surgical Treatment of the Infected Aortic Graft — 2 Figure 1 Standard treatment of aortic graft infection involves axillobifemoral bypass, removal of the infected prosthesis, and oversewing of the aortic stump. This procedure can be performed in either one or two stages. It is most useful in patients who do not have infection extending into the femoral area. patients. Aneurysmal degeneration of the vein grafts is a theoreti- nance angiography can also be a helpful adjunct, particularly in cal risk, but in practice, it is rare. patients with renal insufficiency. When autogenous reconstruction with deep vein grafts is being considered, preoperative assessment of the adequacy of the vein seg- Preoperative Evaluation ments must also be performed.This is accomplished by means of ve- The preoperative workup should assess the extent of infection, nous duplex ultrasonography. Duplex examination of the lower-ex- look for concomitant occlusive disease (indicating a possible need tremity venous system establishes the diameter and the available for infrainguinal, visceral, or renal reconstruction), and determine length of the deep veins. In addition, the duplex scan can evaluate whether there are other associated infectious complications that acute or chronic thrombosis of the deep veins, any recanalization must be treated surgically (e.g., a psoas abscess, an entrapped changes, the congenital absence or duplication of venous segments, ureter with hydronephrosis, or duodenal erosion necessitating and unusually small deep veins.When the FPV is small (< 5 mm), duodenal repair). In patients who have previously undergone absent, or incomplete, a dominant profunda femoris vein is usually prosthetic aortofemoral bypass, infection may be limited to one present.This vein courses posteriorly through the thigh to connect limb of the graft, and it may be treatable by replacing only that with the popliteal vein and can also be used as a venous autograft. limb. In patients who have previously undergone prosthetic Duplex vein mapping of the greater saphenous system is also rou- infrainguinal bypass, the prosthetic graft may have to be removed tinely performed and may provide useful information in the event and replaced with an autogenous graft. that concomitant infrainguinal reconstruction is planned or may Traditionally, the mainstay of the preoperative workup was arte- have to be performed unexpectedly. riography complemented by computed tomography, but current- ly, the workup is increasingly being performed with CT angiogra- phy alone. CT angiography is often capable of evaluating the Operative Planning extent of infection, visualizing the sites of previous prosthetic anas- Removal of an infected aortic graft and autogenous reconstruc- tomoses, and delineating the arterial anatomy. Magnetic reso- tion require prolonged exposure of large portions of the body sur-
  • 3. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 13 Surgical Treatment of the Infected Aortic Graft — 3 Care must also be taken to preserve major branches of the superficial femoral artery when this vessel is occluded or severely diseased. Interruption of these branches, which may supply collat- eral circulation to distal beds, may result in unexpected critical ischemia of the lower extremity after completion of the proximal reconstruction, and further infrainguinal arterial reconstruction may be necessary. STEP 2: DISSECTION OF FPV The FPV has many large and small side branches. Careful, metic- ulous and unhurried ligation of these branches is critical. Most are doubly ligated, with suture ligation reserved for the larger ones. Failure to ligate a branch adequately will result in exsanguinating hemorrhage if a tie loosens and pops off when exposed to aortic pressure. Although as a rule, the FPV is larger and sturdier than the typical greater saphenous vein, it is thin-walled in some areas where branches are present. If a branch is avulsed during dissection, suture repair with 6-0 or 7-0 polypropylene is necessary. Branch ligation during FPV harvesting differs from the typical branch ligation dur- Figure 2 The FPV (thin black arrow), the superficial femoral ing saphenous vein harvesting.The branches of the FPV are ligated artery (thick white arrow), and the saphenous nerve (thin white close to their bases because this is where the vein wall tends to be arrow) lie deep to the sartorius (thick black arrow) in the sub- thin; the larger caliber of the FPV makes this technique possible. In sartorial canal. The sartorius is reflected medially to expose these structures. The adductor magnus tendon is divided to contrast, the branches of the greater saphenous vein, which is of expose these structures as they traverse Hunter’s canal. smaller caliber, are ligated slightly away from the vessel wall to ensure that the lumen of the vein is not encroached on. The extent of the harvest depends on the length of venous con- face. Significant drops in core body temperature, combined with duit required for reconstruction. Proximally, dissection extends to blood loss and resuscitation, may lead to metabolic acidosis, coag- the level of the junction of the femoral and profunda femoris veins. ulopathy, cardiac dysrhythmia, and immune compromise. These veins join to form the common femoral vein, which is also Accordingly, core body temperature should be kept above 36° C exposed in the dissection.The profunda femoris vein is easily rec- (96.8° F) by applying heated-air warming blankets to the upper ognizable as a large posteriorly penetrating vein in the proximal body, using warmed fluid for resuscitation, and maintaining a thigh. Distally, dissection is carried through the adductor hiatus by warm ambient temperature in the operating room. dividing the tendon of the adductor magnus; this measure allows To minimize ischemic time with cross-clamping, the major easy access to the proximal portion of the popliteal vein. The tasks involved in excision of an infected aortic graft and in situ popliteal segment of the vein has multiple large branches, which autogenous reconstruction should be sequenced as follows: (1) must be carefully ligated.The dissection can easily be taken down dissection of FPVs, which are left in situ until needed; (2) isola- to the level of the knee joint. The veins are left in situ until the tion and control of the femoral vessels; (3) entry into the abdomen required length of conduit can be determined. and control of the aorta; (4) removal of the infected prosthesis; and (5) reconstruction with the deep vein grafts.15 STEP 3: DISSECTION AND CONTROL OF FEMORAL VESSELS The femoral vessels can usually be dissected by extending the vein Operative Technique harvest incision cephalad along the lateral border of the sartorius to STEP 1: THIGH INCISION AND EXPOSURE OF FEMORAL VESSELS The patient is placed in the supine position with the legs “frog- legged” and supported under the thighs. An incision is made on the thigh along the lateral border of the sartorius muscle.This lat- eral incision not only facilitates vein harvesting but also allows the surgeon to expose the femoral vessels while avoiding the infected femoral incision medially in the groins. The sartorius is reflected medially so as to preserve the medi- al segmental blood supply.The subsartorial canal is entered, and the femoral vessels are exposed. The femoral vein is usually located posterior to and slightly medial or lateral to the artery at this level. The deep venous system is then exposed from the dis- tal common femoral vein downward, including the proximal profunda femoris vein through Hunter’s canal to the mid- popliteal level [see Figure 2]. The saphenous nerve is located in this canal and is intimately associated with the femoral vessels. Figure 3 Use of a valvulotome typically results in incomplete Care must be taken not to injure this nerve either directly or valve lysis. It is preferable to evert the entire venous graft and through excessive traction; such injury will cause irritating post- excise the valves (which usually number 3 or 4) completely with operative saphenous neuralgia. scissors.
  • 4. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 13 Surgical Treatment of the Infected Aortic Graft — 4 a b c d e Figure 4 Multiple anatomic reconstructions have been used to recreate the aorto-iliac-femoral anato- my. (a) Shown is an aortounifemoral bypass with a femorofemoral crossover. (b) Instead of a femoro- femoral bypass, the second limb may be brought off the midportion of the first limb in an end-to-side manner. (c) If infection is limited to one limb of an aortofemoral bypass, an FPV graft may be used to replace only the infected portion. (d) One segment of vein may be used to replace both segments of an aortoiliac or aortofemoral graft. (e) In some instances, it may be easier to approach the paraceliac aorta via a retroperitoneal approach for the proximal anastomosis. STEP 5: REMOVAL AND PREPARATION OF VENOUS GRAFTS the level of the anterior superior iliac spine. Through this incision, control of the superficial femoral, profunda femoris, and common Before cross-clamping, the vein grafts are removed and pre- femoral vessels is gained. In addition, the distal limbs of the existing pared. The length of the grafts is determined by measuring from aortofemoral graft can be controlled. Occasionally, control is difficult the aortic anastomosis to the femoral anastomoses on both sides. to obtain from a position lateral to the sartorius, in which case the The femoral vein is divided flush with the profunda femoris vein medial aspect of the muscle may be dissected from the subcutaneous and oversewn with a 5-0 polypropylene suture. This creates a tissue to afford improved exposure. Only rarely is a more medial inci- smooth transition point from the profunda femoris vein to the sion required. As noted [see Step 1, above], the lateral approach al- common femoral vein and leaves no stump in which blood can lows the surgeon to avoid entering the previous incision, where there stagnate and create thrombus. The grafts are then distended in a may be a draining sinus or cellulitis. 4° C solution containing lactated Ringer solution (1 L), heparin (5,000 U), albumin (25 g), and papaverine (60 mg). Any leaks are STEP 4: ABDOMINAL INCISION AND DISSECTION OF AORTA repaired either with additional silk ties or with figure-eight fine The abdomen is then entered either through a midline abdomi- polypropylene sutures. Any adventitial bands that distort the nal incision or via a retroperitoneal approach; the latter is particu- lumen are lysed. larly helpful in avoiding tedious abdominal adhesions. Dissection Next, the valves in the grafts must be lysed.This is a critical step for control of the aorta above the aortic anastomosis is performed. because the grafts are placed in a nonreversed fashion to optimize The anastomosis may be near the level of the renal arteries, in which size matching with the aorta for the proximal anastomosis. case suprarenal or supraceliac aortic control may be required. Valvulotomes have been used for valve lysis in these large-caliber
  • 5. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 13 Surgical Treatment of the Infected Aortic Graft — 5 veins, but the results have been unsatisfactory: lysis is often incom- formed so as to cut down on the blood loss that typically occurs plete, and the remnants of the valves may become sites of graft when the limbs are removed from their tunnels. stenosis. Our current practice is to evert venous grafts completely Multiple configurations have been successfully employed to and to excise all valves under direct vision [see Figure 3]. reconstruct the distal aortic and iliac-femoral vasculature [see Figure 4].The proximal anastomosis is performed with a continu- STEP 6: REMOVAL OF BODY OF PREVIOUS GRAFT AND ous 4-0 polypropylene suture. The diameter of the FPV graft is PROXIMAL ANASTOMOSIS OF NEW GRAFT TO AORTA typically about 1.5 cm or a little greater, and the mismatch in The patient is heparinized, and the aorta above the anastomo- diameter between the graft and the aorta is dealt with by taking sis and both limbs of the graft are cross-clamped.The body of the slightly more advancement (i.e., placing sutures slightly farther graft is then excised, with the limbs left in place. All prosthetic apart) on the aortic wall than on the graft wall [see Figure 5a]. If material, including sutures, is removed. The previous aortic anas- the caliber discrepancy between the two structures is too large, tomosis may have been done in either an end-to-end or an end- another technique must be employed, such as plication of the to-side fashion. If it was an end-to-side anastomosis, the distal end aorta, joining of the venous grafts in a pantaloon configuration, or of the aorta will have to be oversewn with a large suture (e.g., 0 or placement of a triangular patch at the proximal aspect of the graft No. 1 polypropylene). Balloon occlusion of the distal lumen is a [see Figures 5b through 5d]. helpful adjunctive measure before ligation. Regardless of how the After the proximal anastomosis is complete, the venous graft is previous aortic anastomosis was done, the new anastomosis is typ- distended under aortic pressure, and the side branches are care- ically constructed in an end-to-end fashion.The distal limbs of the fully examined to confirm that all ligatures are securely placed. existing graft are left in place while the aortic anastomosis is per- Any questionable areas are repaired. Anastomotic leakage is also repaired with the aorta clamped to ensure that the venous graft is not torn during repair. a b STEP 7: REMOVAL OF LIMBS OF PREVIOUS GRAFT AND DISTAL ANASTOMOSES OF NEW GRAFTS TO FEMORAL ARTERIES The femoral limbs of the prosthetic aortobifemoral grafts are then removed by pulling them through the groin incisions. When the FPV grafts are tunneled to the groins, care must be taken to ensure that ligated side branches are not torn or dislodged. Because it may be difficult to create new tunnels through the scarred retroperitoneum, the vein grafts may be tunneled through the existing tunnels. In many cases, the existing tunnels are small- er in caliber than the new vein grafts, and careful digital dilation of the tunnels is required. The femoral anastomoses are fashioned in a standard manner. Once again, all prosthetic material and all surrounding infected tissue must be debrided from the groins. On occasion, profun- c d daplasty or reimplantation of the profunda femoris may be re- quired. If possible, the femoral anastomoses should be done in an end-to-side manner to preserve retrograde pelvic perfusion. Perfusion of the extremities must be assessed before the leg wounds are closed. If Doppler arterial signals are absent at the level of the ankle, a femoropopliteal or distal bypass may be nec- essary [see 6:17 Infrainguinal Arterial Procedures]. Because the popliteal artery is exposed during FPV harvesting, adjunctive femoropopliteal bypass is easily accomplished in this setting. STEP 8: CLOSURE After reversal of heparinization, the thigh wounds are copious- ly irrigated and closed over closed suction drains. Placement of drains prevents postoperative seromas and subsequent wound complications. Even though these wounds are contaminated as a consequence of the proximity of the infected graft in the groin wound, infection is rare. Often, there are draining sinuses medial to the vein harvest incisions, which are debrided and left open. Figure 5 (a) An end-to-end proximal anastomosis is usually possible if the diameter of the FPV graft is large enough and the aorta is of normal size. (b) If the end of the aorta is significantly Postoperative Care larger in diameter than the venous graft, plication of the aorta can be performed. (c) A pantaloon technique may also be used to Parenteral antibiotics are continued for 5 to 7 days, and antibi- deal with a size mismatch between the aorta and the FPV graft. otic coverage is modified on the basis of intraoperative cultures of This technique effectively doubles the circumference of the vein. the graft material and wound swabs. Intermittent pneumatic (d) The proximal anastomosis can also be facilitated by incorpo- compression and low-dose subcutaneous heparin (5,000 U every rating a wedge-shaped portion of vein into the proximal end of 8 to 12 hours) are employed for prevention of deep vein thrombo- the graft. sis.Thrombosis of the residual popliteal vein is common, and ag-
  • 6. © 2005 WebMD, Inc. All rights reserved. ACS Surgery: Principles and Practice 6 VASCULAR SYSTEM 13 Surgical Treatment of the Infected Aortic Graft — 6 gressive prophylaxis may prevent extension of the thrombus into ical examination of the legs.We specifically assess progressive com- the calf veins. With the FPV absent, the risk of pulmonary em- partment swelling and firmness on serial examination after reper- bolism is low. fusion of the lower extremities.We also consider risk factors in mak- ing this decision. Two specific risk factors for fasciotomy are (1) a low preoperative ABI (< 0.4) and (2) concurrent greater saphenous Complications vein harvesting.13 Other factors may also help determine the need The incidence of chronic venous morbidity after FPV harvesting for fasciotomy, including the indication for operation, the length of is low, but the fasciotomy rate is approximately 20%. In our prac- vein harvested, the duration of arterial cross-clamping, and the tice, the decision to perform a fasciotomy is based primarily on clin- amount of fluid administered intraoperatively. References 1. Quinones-Baldrich WJ, Hernandez JJ, Moore WS: 1998). J Vasc Surg 30:92, 1999 12. Jackson M, Ali A, Bell C, et al: Aortofemoral bypass in Long-term results following surgical management of 7. Young RM, Cherry KJ, Davis PM, et al:The results of young patients with premature atherosclerosis: is su- aortic graft infection. Arch Surg 126:507, 1991 in situ prosthetic replacement for infected aortic perficial femoral vein superior to Dacron? J Vasc Surg 2. Speziale F, Rizzo L, Sbarigia E, et al: Bacterial and grafts. Am J Surg 178:136, 1999 40:17, 2004 clinical criteria relating to the outcome of patients un- 8. Batt M, Magne JL, Alric P, et al: In situ revasculariza- 13. Modrall JG, Sadjadi J, Ali A, et al: Deep vein harvest: dergoing in situ replacement of infected abdominal tion with silver-coated polyester grafts to treat aortic predicting need for fasciotomy. J Vasc Surg 39:387, aortic grafts. Eur J Vasc Endovasc Surg 13:127, 1997 infection: early and midterm results. J Vasc Surg 2004 3. Kieffer E, Gomes D, Chiche L, et al: Allograft replace- 38:983, 2003 14. Wells JK, Hagino RT, Bargmann KM, et al: Venous ment for infrarenal aortic graft infection: early and late 9. Clagett GP, Bowers BL, Lopez-Viego MA, et al: Cre- morbidity after superficial femoral-popliteal vein har- results in 179 patients. J Vasc Surg 39:1009, 2004 ation of a neo-aortoiliac system from lower extremity vest. J Vasc Surg 29:282, 1999 4. Bandyk DF, Novotney ML, Back MR, et al: Expand- deep and superficial veins. Ann Surg 218:239, 1993 15. Clagett GP: Treatment of aortic graft infection. Cur- ed application of in situ replacement for prosthetic 10. Nevelsteen A, Lacroix H, Suy R: Autogenous recon- rent Therapy in Vascular Surgery, 4th ed. Ernst CB, graft infection. J Vasc Surg 32:451, 2000 struction with the lower extremity deep veins: an alter- Stanley JC, Eds. CV Mosby, Philadelphia, 2001, p 422 5. Walker WE, Cooley DA, Duncan JM, et al:The man- native treatment of prosthetic infection after recon- agement of aortoduodenal fistula by in situ replace- structive surgery for aortoiliac disease. J Vasc Surg ment of the infected abdominal aortic graft. Ann Surg 22:129, 1995 205:727, 1987 11. Clagett GP, Valentine RJ, Hagino RT: Autogenous 6. Hayes PD, Nasim A, London NJM, et al: In situ re- aortoiliac/femoral reconstruction from superficial Acknowledgment placement of infected aortic grafts with rifampin- femoral-popliteal veins: feasibility and durability. J Vasc bonded prostheses: the Leicester experience (1992 to Surg 25:255, 1997 Figures 1, 4, and 5 Alice Y. Chen.