Aortic Bifemoral (Aortobifemoral) Bypass

Aortic bifemoral (aortobifemoral) bypass is a surgical procedure that is performed in patients with atherosclerotic disease of the infrarenal aorta and iliac vessels (see the images below).[1] Most patients who undergo this procedure have symptoms of claudication, impotence, and poorly healing ulcers. Examination usually reveals absent or very weak femoral pulses.

Endovascular revascularization has become a first-line treatment for aortoiliac occlusive disease.[2] However, aortic bypass grafting remains one of the best techniques for exposing and repairing aortic or iliac vessel disease. Although unilateral reconstruction of the iliac vessels used to be common, aortobifemoral bypass is currently preferred. The contralateral disease usually progresses, and a bilateral femoral bypass eliminates future revision of a unilateral bypass.[3, 4, 5]

The aortic bifemoral bypass is considered to be the most durable of all bypasses for the peripheral system. It is an ideal procedure for patients with aortoiliac disease, aortic aneurysms extending into the iliac arteries, or aortic atherosclerosis.[6]

Indications for aortic bifemoral bypass include the following:

• Atherosclerosis of the abdominal aorta or iliac arteries
• Presence of severe claudication symptoms
• Impotence
• Nonhealing ulcers in the extremities
• Aortic aneurysms involving the iliac arteries for which aortoiliac bypass cannot be safely performed
• Acute abdominal aortic occlusion
• Critical limb-threatening ischemia (CLTI)

The procedure can be combined with renal artery or superior mesenteric artery (SMA) revascularization if symptomatic stenoses are present in these visceral vessels.[3, 4, 5]

In some patients with severe aortoiliac occlusive disease (AIOD), aortoiliac stenting with bifurcation reconstruction (AISBR) may be an alternative to aortobifemoral bypass.[7]

Because aortic bifemoral bypass requires general anesthesia and is an extensive procedure, it is contraindicated in patients who are very old, frail, and unfit for surgery. Moreover, patients with symptomatic heart disease, recent stroke, or myocardial infarction (MI) need an extensive preoperative workup.

Those who have a very hostile abdomen (eg, from a previous colostomy), retroperitoneal fibrosis, or horseshoe kidney should be carefully worked up; surgery can be very demanding in these settings and is often associated with extensive blood loss.[3, 4, 5]  Patients with end-stage renal disease (ESRD) who are on dialysis constitute a high-risk group.[8]

Accurate assessment of the aorta and the iliac vessels is critical. Other options for treating aortoiliac disease may be considered. Appropriate patient preparation will minimize complications.

Best practices

A number of radiologic tests can help assess the aorta and iliac vessels. Conventional angiography, the previous standard, is being supplanted by computed tomography (CT) angiography (CTA) and magnetic resonance angiography (MRA).

The benefits of CTA include a peripheral needle-injection site and superb three-dimensional (3D) reconstruction images. The biggest disadvantage of CTA is that visualization of stenosis in the small vessels in the legs is not always possible. MRA is fast becoming a favored technique for visualizing large blood vessels; however, it tends to amplify the degree of stenosis.[3, 4, 5]

One benefit of contrast angiography is the ability to define the dynamics of collateral vessels and determine how they contribute to the reconstitution of the femoral, popliteal, and even visceral vessels. (See the image below.)

Procedural planning

In aortic surgery, as in most branches of surgery, minimally invasive[9]  and laparoscopic techniques have been introduced with the aims of improving outcome, decreasing postoperative pain, and shortening the hospital stay. In the past two decades, many experimental and clinical studies have attempted laparoscopic aortic bifemoral bypass. However, this technique is still challenging, and there is a need for better instruments. Current instruments do not allow very fine anastomoses to be made in difficult areas of the body (eg, the groin and pelvis).

The technique of laparoscopic aortobifemoral bypass surgery for aortoiliac disease has improved. A randomized trial revealed that the laparoscopic approach was safe and resulted in significantly lower postoperative morbidity, reduced stay in the hospital, and faster recovery. However, the number of patients was small and the follow-up period short.[10]  

Work by Segers et al suggested that the EndoVascular REtroperitoneoScopic Technique (EVREST), a clampless and sutureless aortic anastomotic technique used during retroperitoneal laparoscopic aortobifemoral bypass in extensive aortoiliac occlusive lesions, appears to be both feasible and safe in this setting.[11, 12]

Despite the plethora of reports on laparoscopic vascular procedures, the results are not yet considered to have matched those obtained with open techniques.[13]  Moreover, complications of laparoscopic procedures continue to occur, and there is still a need for long-term data.[14, 15, 16]  To make matters worse, the reporting of complications during laparoscopic procedures is not mandatory, and most complications are underreported.

At present, laparoscopic aortic bifemoral bypass is less widely performed than the equivalent open procedure.[17, 18, 19, 20, 21]  It is not the criterion standard.[22] Future improvements in instrumentation and ongoing development of surgeons' skills may someday make this procedure more routine.[23]

Besides open surgery, there are several options for treating disease in the aorta and iliac vessels, including the following:

• Angioplasty, with or without stenting
• Endovascular bypass
• Extra-anatomic bypass grafting

Angioplasty, with or without stenting, is an ideal option for isolated lesions in the iliac artery. Currently available stents have excellent patency rates for the iliac vessels. Long lesions in the iliac vessel can be treated with angioplasty, but the results are not durable in the long term.[3, 4]

The chief advantage of angioplasty is that it eliminates the morbidity associated with aortic bifemoral bypass. Except for bleeding at the groin site and pseudoaneurysm, complications are much less common with angioplasty. Recurrence of stenosis is a problem and may present as recurrence of symptoms.

A unilateral endovascular aortofemoral bypass is performed with available prosthetic material. The proximal end of the aorta is held with a Palmaz stent and sent into the ipsilateral outflow vessel. The procedure is then completed with an associated femorofemoral bypass. There remains a need for additional long-term follow-up data.[3, 4]

In a small study, patients with total occlusion of the aorta were successfully treated by using an endovascular approach, and midterm patency was favorable. The authors warned that patient selection for this procedure is crucial. The rates of procedural complications, such as embolization, pseudoaneurysm, and artery rupture, are high.[24]

Advances in endovascular techniques led to the development of various clampless and sutureless devices for the proximal aortic anastomosis. Here too, there remains a need for long-term data.[25] Similar sutureless devices were once recommended for the proximal anastomosis of the vein graft during coronary bypass surgery, but the results were abysmal owing to severe anastomosis at the site in just a few months. Until more long-term data are available, caution should be exercised in using such grafts.

Studies by Maldonado et al[26] and Van Haren et al[27]  reported good midterm results with the use of a unibody bifurcated endograft (Endologix; Irvine, CA) to treat complex aortoiliac occlusive disease.

In some cases, a patient may have significant aortoiliac disease but may not be a candidate for general anesthesia. For these patients, options such as extra-anatomic bypass grafts are available. Femorofemoral bypass and axillofemoral bypass are decent alternatives to aortic revascularization. Femorofemoral bypass is an excellent procedure if one iliac artery is normal. Axillofemoral bypass is suitable for high-risk patients in whom a transabdominal procedure cannot be performed.

In rare cases, the surgeon may also use the thoracic aorta as an inflow vessel and then tunnel the graft into the groin. Others have used the ascending aorta as an inflow vessel. Use of the thoracic aorta requires a concomitant lateral thoracotomy, whereas use of the ascending aorta requires a median sternotomy. These are rare procedures and are not performed at all community hospitals. Sometimes, aortic bifemoral bypass is combined with a median sternotomy and coronary artery bypass.[28, 29]

Complication prevention

To prevent complications, a careful workup is essential. In all patients, cardiac and respiratory status must be assessed before the aortic procedure; at least 10-20% of patients have significant coronary artery disease (CAD) that may have be addressed preoperatively. In particular, all high-risk patients must be cleared by the cardiologist before the procedure because most of these patients have CAD.

Even though there are reports of combined coronary artery bypass and aortofemoral bypass procedures being performed in the same setting, these are isolated reports and do not represent the standard of care. Complications with combined procedures are significant.

In the hands of experienced surgeons, the mortality for aortic bifemoral bypass is 2-5%. In hospitals where the surgery is not regularly performed, mortality is much higher. The most common causes of death after surgery are perioperative myocardial infarction (MI) and stroke. Other causes of death include renal and respiratory failure. At 5 years, mortality is 25-30%; at 10 years, mortality is 50%.[3, 4]

Meta-analysis of multiple studies reveals that the long-term patency of aortic bifemoral bypass grafts ranges from 91% at 5 years to 80% at 10 years. Patency rates are lower if the procedure is performed in patients with ischemic rest pain, ulcerated toes, or coexisting distal disease. Although women tend to have smaller blood vessels, there is no evidence that the results of the procedure are any worse in women than in men.[3, 4, 5]

A study by DeCarlo et al found that the Society for Vascular Surgery (SVS) femoral runoff score, which can be determined from preoperative axial imaging studies, is associated with long-term limb patency after aortofemoral bypass, with scores of 6 or higher portending worse limb outcomes and a greater incidence of operative complications.[30]

A retrospective review of laparoscopic aortobifemoral bypass surgery for aortoiliac occlusive diseases by Bath et al assessed 46 patients over a 10-year period at a single center.[31]  The approach was completely laparoscopic in eight patients and laparoscopic-assisted in 38. Median length of stay was 6 days (range, 2-30). Within 30 days, there were two MIs (4.3%), one transient ischemic attack (2.2%), and one death (2.2%). Twelve patients (26.1%) required reintervention during the study period. Primary, primary-assisted, and secondary patency rates at 60 months were 79.4%, 93.9%, and 94.9%, respectively. Overall mortality was 17% at a mean follow-up of 60 months (range, 1-116).

Patients who smoke should be asked to discontinue tobacco for at least 4 weeks before surgery.

Patients who are taking a nonsteroidal anti-inflammatory drug (NSAID) should be asked to stop the medication 5-7 days prior to the procedure. If the patient is taking warfarin, he or she should be admitted and started on heparin 2-3 days before surgery. The heparin should be discontinued at midnight before the day of the procedure.

Patients should be asked to discontinue all herbal products before the procedure.

Patients with risk factors for heart disease should be cleared by the cardiologist. If the patient is a heavy smoker, a pulmonary consult should be obtained.

Laboratory evaluation should include the following:

• Complete blood count (CBC)
• Coagulation profile, including international normalized ratio (INR), prothrombin time (PT), and partial thromboplastin time (PTT)
• Platelet count
• Renal and liver function tests
• Urinalysis
• Chest x-ray
• Electrocradiography (ECG)
• Cross-matching and typing of two units of blood

Aortic bifemoral (aortobifemoral) bypass is an extensive procedure that requires careful patient preparation. For elective surgery, the patient should not smoke for at least 3-4 weeks, and on the day of surgery, two to four units of packed red blood cells should be available. Autologous blood donation is recommended in most elective cases.

Adequate hydration is recommended before surgery, and an intravenous (IV) fluid drip should be started at midnight. A broad-spectrum antibiotic is administered just before the incision is made.

In most aortic bifemoral bypass procedures, blood transfusion can be avoided through proper hemostasis and careful dissection. A cell saver, if available, can help decrease the need for blood transfusions.[32]  Better still, autologous blood donation can be done 3 weeks in advance of elective surgery. Routine use of blood during aortic bifemoral bypass is not recommended.[3]

Anesthesia

Aortobifemoral bypass is an extensive procedure and requires general anesthesia. A central venous line is placed for monitoring and fluid access during anesthesia. A radial line is usually inserted for continuous monitoring of blood pressure.[32]

In patients with heart problems, a Swan-Ganz (pulmonary artery) catheter may be used to monitor cardiac function. Today, most patients are given a combination of spinal and general anesthesia. The epidural catheter is left in place for a few days to limit pain; this can significantly reduce exogenous narcotic requirements.

All fluids are warmed before administration, and the upper body is covered with a warming unit (eg, Bair Hugger).[3, 4, 5]

Positioning

For an aortic bifemoral bypass, the patient is placed in the supine position, with the arms extended at the side. The infrarenal aorta can be exposed via several different incisions, but the most common choice is a midline abdominal incision extending from the xiphoid to the pubis.[3, 4, 5, 33, 34]

The 2018 guidelines from the Society for Vascular Surgery (SVS) recommended clinical examination and ankle-brachial index (ABI) measurement, with or without the addition of duplex ultrasonography (US), in the early postoperative period to provide a baseline for further follow-up after aortobifemoral bypass; this evaluation would be repeated at 6 and 12 months and then annually as long as there are no new signs or symptoms.[35]

A retrospective study by Maloni et al found duplex US to be a useful surveillance tool for identifying aortobifemoral bypasses that are failing or have other problems not identified clinically.[36]

Depending on the patient, continuous electrocardiographic (ECG) monitoring, arterial line monitoring, and a central venous line or a Swan-Ganz (pulmonary artery) catheter can be used. Routine use of the pulmonary artery catheter has not been associated with a decline in mortality.

Perform the operation using a combination of general and epidural anesthesia. Prepare the entire chest and abdomen up to the knees.

Aortic bifemoral (aortobifemoral) bypass may be performed via either a transperitoneal or a retroperitoneal approach. The procedure takes 3-4 hours. (See the images below.)

Operative exposure

Make two small longitudinal incisions in the groin to expose the common femoral artery at its bifurcation. If the bifurcation of the femoral artery is high, it may be necessary to cut the inferior segment of the inguinal ligament. Perform gentle dissection to develop a tract from the groin into the retroperitoneal space to the anterior iliac artery and the lateral circumflex vein. Pack the groin wounds with moist gauze.[3, 4, 5]

Make a midline abdominal incision that extends from the xiphoid to just below the umbilicus. Carefully examine the abdomen. Lift the transverse colon superiorly, then collect the small bowel to the right side and place it in a bowel bag.

Alternatively, obtain exposure of the aorta through a retroperitoneal approach via an incision made along the course of the left 10th or 11th rib and extended anteriorly. Once the retroperitoneal space is entered, it is the surgeon’s choice whether to proceed by elevating the left kidney and all of the abdominal contents or by traversing along a plane anterior to the left kidney toward the aorta.

Once the retractors are placed, perform sharp dissection on the right side of the inferior mesenteric vein (IMV). Carry the dissection directly onto the wall of the aorta. Avoid lateral dissection; damage can occur to the inferior vena cava (IVC) on the far right and the inferior mesenteric artery (IMA) on the left. The origin of the IMA is usually visible on the left side of the aorta; it is not dissected, but its location is noted.

Minimally dissect distally over the aortic bifurcation, and do not attempt to ligate the lumbar veins. Preserve all preaortic nerves and the sacral plexus in the distal aorta with minimal dissection. Carefully isolate both common iliac arteries. Proximally, carry the dissection up to the duodenum and identify both renal arteries. Make room in the proximal aorta for placement of a clamp.

Never dissect underneath the proximal aorta if the left renal vein has not been visualized anteriorly. In at least 10% of cases, the left renal vein runs posterior to the aorta and can easily be damaged by a retrograde clamp. If this ever happens, the bleeding can be torrential and difficult to control.

Heparin, 100 units/kg, is administered by the anesthesiologist 5 minutes before the aorta is clamped. Before clamping the proximal aorta, the anesthesiologist must be ready to manage any surge in blood pressure.[3, 4, 5]

Proximal anastomosis

Today, many choices of aortic grafts are available for aortofemoral bypass, but in most cases, Dacron or expanded polytetrafluoroethylene (ePTFE) is chosen. The standard graft size used by most surgeons is 14 × 7 mm. Some surgeons prefer to match the graft to the size of the patient or the aorta, but doing so does not appear to yield any differences in long-term results.[37, 3, 4]

Once the proximal clamp is applied just below the renal vessels, do not attempt to dissect posterior to the aorta. Divide the aorta about 1.5 cm distal to the clamp. Remove a small oblique segment of anterior aorta to allow visualization of the inner aorta. Cut the prosthetic graft so that only about 3 cm of the trunk remains with the bifurcated segment.[34]

If the aortic disease is at the level of the renal arteries, place the proximal clamp above the renal vessels. Exposure is often improved if the left renal vein is retracted in a vessel loop. It is crucial to visualize both renal arteries before placing the clamp. Sometimes, a change must be made in the graft anastomosis. To prevent postoperative renal dysfunction, the proximal anastomosis should be completed in less than 30 minutes.[28]

Perform the proximal aortic anastomosis in either an end-to-side or an end-to-end fashion. Perform an end-to-side anastomosis when there is an aberrant renal artery that supplies a large portion of the kidney or a large mesenteric artery that must be preserved. Another indication is a male patient who does not want to develop libido after surgery and who has significant disease of the external iliac vessels or a hypoplastic aorta.[3, 4, 5]

An end-to-end anastomosis is indicated if there is coexisting aortic aneurysmal disease or complete aortic occlusion that extends up to the renal arteries. Most surgeons prefer an end-to-end anastomosis, believing that it yields much better hemodynamic results than an end-to-side anastomosis does. However, there is no solid evidence that one technique is superior to the other in this regard; the final choice is strictly personal. Some evidence suggests that intraoperative atheroembolic episodes may be less frequent with end-to-side anastomoses.

Perform the proximal anastomosis with a 3-0 polypropylene suture, starting in the posterior wall and continuing to the front with both needles. Take large bites of the native aorta to ensure that the anastomosis will be secure. Moisten and tighten the suture before tying it. Use a nerve hook to identify any loose sutures. To assess the patency of the proximal anastomosis, clamp the distal graft and gently release the proximal aortic clamp. Repair all leaks at this stage.

A single-center, long-term, prospective randomized study monitored grafts in 99 patients after open surgical repair of abdominal aortic aneurysms.[38] After 6 years, ePTFE grafts were the least likely to dilate as compared with polyester grafts. However, the overall differences between the grafts were not significant. Even though ePTFE grafts are reliable and durable, all prosthetic grafts used in vascular surgery must be monitored on a regular basis to ensure that there is no expansion.

Distal anastomoses

Once the proximal anastomosis is done, recheck it, then carefully tunnel the graft limbs into the groin area.[3, 4, 5]  Pass a long curved clamp from each groin, and bring the graft into the retroperitoneum on each side. Take care when creating the tunnel. Structures that can be injured here include the colon, the ureters, and the iliac veins. Once the grafts on both sides of the groin have been laid out, place the proximal aortic clamp more distally.

The distal anastomoses in the two sides of the groin are usually made at the bifurcation of the common femoral artery and onto the proximal deep femoral artery, regardless of the status of the superficial femoral artery. Some surgeons perform the distal anastomosis to the external iliac artery, but unless the external iliac is completely free of disease, a distal repair may be required in the future to improve runoff.

Place clamps on the proximal common femoral artery, superficial femoral artery, and deep femoral artery. Create a small (1.0-1.5 cm) arteriotomy, and carry a beveled anastomosis out to the graft. Do not narrow any of the vessels during the anastomosis. If there is any doubt about backflow, perform an embolectomy or choose a more distal target vessel on the deep femoral artery. Do not unnecessarily ligate any branches of the femoral artery. Most surgeons have to perform some degree of endarterectomy on the femoral vessels.

Perform the anastomosis with a 5-0 polypropylene suture. Before tying the anastomosis, carry out flushing maneuvers to remove emboli and air bubbles. Before removing any clamps, notify the anesthesiologist to resuscitate the patient. Gently remove the clamp from the proximal aorta, then remove one clamp at a time from each groin. Usually, there is a slight drop in blood pressure from the buildup of lactate and metabolites while the femoral artery was clamped.

Once blood pressure has stabilized, check all of the sites to confirm that the anastomoses are good. Obtain complete hemostasis, and feel the pulses in both groins. The color of the sigmoid colon should be pink. Before reversing the anticoagulation, confirm the presence of pulses or Doppler signals in the feet.

Closure

Give protamine to reverse the heparin, and count all instruments and sponges. Carefully return the bowel, and close the peritoneal layer. Close the abdominal wall with a 1-0 monofilament suture. Before closing the groin, assess the pulses again in both groins. If there is any concern about pulses, on-table angiography is highly recommended. Perform groin closure in three layers, and cover the entire graft.

Extubate the patient in the operating room (OR) or in the intensive care unit (ICU) if he or she is stable. Postoperatively, monitor patients for respiratory, cardiac, and renal function. Most important, check pulses in the legs every few hours. Most patients can leave the ICU the next day and can be admitted to a regular floor.

Administer antibiotics for three doses after the procedure, and discharge the patient once he or she is ambulating and tolerating a diet. Ambulation can start on postoperative day 2, but a normal diet should not be resumed until the patient has active bowel sounds. Perform a duplex arterial study on the day of discharge to provide an objective baseline for follow-up studies.[3, 4, 5]

Overall, complications from aortic surgery appear to be more common in institutions where the procedure is performed sporadically. Many postoperative complications are caused by inexperience and lack of technical skill on the part of the surgeon.[39]

Myocardial infarction

Myocardial infarction (MI) is a well-known complication after aortic bifemoral bypass. Accordingly, all high-risk patients undergo preoperative screening for significant coronary artery disease (CAD). Patients without a history of CAD and an abnormal ECG can undergo surgery without cardiac work-up. Patients with an abnormal ECG who are at risk for CAD usually undergo a treadmill test, dipyridamole thallium screening, echocardiography, or coronary angiography.

Some patients who have isolated lesions of the coronary arteries undergo stenting before the aortic procedure. Individuals who are not candidates for coronary bypass surgery are usually at high risk for anesthesia and should only undergo an extra-anatomic bypass. The Swan-Ganz catheter is widely used to monitor patients, but it does not reduce morbidity, and it may even provide misleading information in some patients with CAD.

Patients who have symptomatic carotid artery disease should undergo endarterectomy before the aortic procedure. Asymptomatic patients with internal carotid artery disease can undergo aortic surgery.[3, 4, 5]

Respiratory dysfunction

Patients with significant pulmonary disease can have problems postoperatively. Most smokers should quit smoking at least 4 weeks before surgery and should undergo chest physiotherapy and a trial of bronchodilators and antibiotics if there is evidence of lung infection. These patients may benefit from preoperative incentive spirometry, early extubation, and aggressive chest physiotherapy. Epidural anesthesia may help.[3, 4]

Renal dysfunction

Renal failure is not common after aortic bifemoral bypass. Worsening of kidney function is more likely if there is preexisting renal failure, if the aorta is clamped above the renal arteries, or if the renal vein is ligated or damaged. Other factors that can worsen renal injury include the use of contrast dye, dehydration, and embolism.[3]

Bleeding and coagulopathy

In patients who receive multiple transfusions, coagulopathies can occur. Accordingly, the coagulation parameters must be normal before surgery. Rarely, heparin-induced thrombocytopenia may occur, which may result in unexplained thrombosis.[3, 4]

Sexual dysfunction

When extensive dissection is performed over the distal aorta and left common iliac artery, decreased sexual function may result. If the periaortic sympathetic fibers are damaged, retrograde ejaculation can occur.

Precise surgical technique is the only way to prevent this disturbing side effect. On the distal aorta, dissection should be limited to the right side. If severe iliac artery disease is present, an end-to-side anastomosis is preferred to maintain retrograde flow to the external iliac branches. Some surgeons perform iliac artery endarterectomy to improve erectile function, but the results are not consistent, and there is a risk of nerve injury.[3, 4]

Ureteral obstruction

When dissection is carried out very lateral or posterior to the aorta, damage to the ureter is a risk. Other causes of ureteral damage may include ischemia, accidental grasping, and injury during tunneling. The dense fibrosis from the prosthesis reaction can also cause ureteral obstruction.

Mild hydronephrosis from edema occurs in 10% of cases and usually resolves spontaneously. Early hydronephrosis usually necessitates reoperation. Delayed hydronephrosis is often associated with fibrosis. Computed tomography (CT) is often required to identify the dense adhesions. Ureteral complications call for consultation with a urologist and may necessitate kidney decompression, adhesiolysis, or ureter reimplantation.[3, 4, 5]

Sigmoid colon ischemia

Clinically significant ischemia is seen in 1-2% of individuals and is typically detected by means of colonoscopy. The sigmoid colon is perfused by the IMA and collateral branches from the internal iliac artery and the deep femoral artery. Sigmoid colon ischemia can occur when antegrade flow though a large IMA is decreased during surgery, when the collateral flow is poor because of superior mesenteric artery (SMA) disease, or when perfusion pressure is diminished.

Operative trauma involving damage to the collaterals is one of the most common causes of sigmoid colon ischemia. If the large IMA is present with little antegrade flow, one must consider an end-to-side aortic anastomosis with preservation or reimplantation of the IMA. Routine reimplantation is not required in all patients. The best way to avoid bowel complications is to observe the sigmoid colon after surgery. If the colon appears ischemic, the IMA may have to be reconstructed. Sometimes, the SMA must be reconstructed to improve flow to the colon.

Any patient who presents postoperatively with fever, left-lower-quadrant pain, or bloody diarrhea should undergo sigmoidoscopy and early decompression of the colon. Transmural colon ischemia accrues a mortality in excess of 60%.[40]

Important predictors of colon ischemia include systemic hypotension, the surgeon's relative inexperience or lack of sufficient technical skill, prolonged operating times, long cross-clamp times, ligation of the internal iliac artery, and patient-related factors such as age, kidney disease, and atherosclerosis. Besides infarction, other colon complications include strictures and fibrosis.[3, 4, 5]

Emboli and "trash foot"

"Trash foot" occurs when emboli are washed downstream and end up in the distal leg. The showering emboli may produce distal toe gangrene even in the presence of intact pulses. The best way of managing trash foot is to prevent it by employing proper surgical technique and gentle manipulation of the aorta.

Paralysis/paraplegia

Paraplegia may occur after aortic bifemoral bypass, but it is very rare. Causes include severe hypotension, reduction of pelvic blood flow because of interruption of internal iliac flow, and emboli. The degree of paralysis is variable and may involve peripheral nerve roots, reduction in tendon reflexes, and patchy sensory loss. The level of injury is often difficult to discern, and the condition may have to be differentiated from cauda equina syndrome.

Treatment of paraplegia is supportive, but in most cases, the injury is permanent. Although a few patients with incomplete paralysis may show improvement over the years, such a result is a rarity. Lower motor neurons typically recover better than upper motor neurons do.[3, 4, 5]

Ileus

Ileus is common after surgery. It may take a few days for bowel activity to return to normal. In a few patients, a nasogastric tube may be required to decompress the stomach.

Graft occlusion

Graft occlusion usually occurs many years after the operation and may present as unilateral claudication or rest pain. Recurrence of symptoms is a sure sign that one of the distal limbs of the graft is narrowed or occluded. Treatment may include thrombolytic agents, thrombectomy, femorofemoral bypass, or distal bypass to improve the outflow of the graft limb.[41]

Anastomotic pseudoaneurysm

A pulsatile mass may occur in the groin, possibly indicating the presence of a pseudoaneurysm. The pseudoaneurysm may have resulted from an infection or from anastomotic failure. Surgical repair is required for all groin pseudoaneurysms, regardless of etiology.[3, 4, 5]

Aortoenteric fistula

Aortoenteric fistula is a rare but lethal complication that results from infection of the proximal aortic graft suture line into the fourth part of the duodenum. This may present initially as a small herald intestinal bleed, which is followed by massive blood loss. The traditional treatment consists of emergency surgery with removal of the aortic grafts, suture closure of the proximal aorta, and placement of an extra-anatomic bypass. Alternative treatments include reconstruction with femoral vein grafts or cryopreserved grafts. The mortality is significant.[19, 4, 42]

Complete CBC

Coagulation profile including INR, PT an PTT

Platelet count

Renal and liver function

Urinalysis

Chest X-ray

ECG

Cross and type 2 units of blood