Thoracofemoral (Thoracic Aortofemoral) Bypass

The typical treatment for aortoiliac occlusive disease is an aortofemoral bypass graft, with patency rates of approximately 83-92% at 5 years.[1] Less invasive approaches have been studied.[2, 3] Thoracofemoral (thoracic aortofemoral) bypass is an alternative surgical bypass that is indicated for aortoiliac occlusive disease when traditional aortobifemoral bypass is contraindicated.[4] These conditions occur when performing a transabdominal or retroperitoneal abdominal procedure is difficult or impossible, as may be the case, for example, in the following circumstances:

• Prior abdominal irradiation
• Multiple abdominal interventions
• Colostomy
• Proximal aortic disease in close proximity or above the renal arteries
• Failure or infection of previous abdominal aortic surgery

Some surgeons have advocated thoracofemoral bypass as a primary treatment for isolated aortoiliac occlusive disease, at least when the disease is in close proximity to the visceral or renal arteries.[1] Reported patency rates for thoracofemoral bypass have rivaled those of the traditional aortofemoral bypass, at approximately 81% at 5 years.[1]

Indications for thoracofemoral bypass include the following:

• Aortic graft failure ^[5]
• Graft infection
• Hostile abdomen ^[6]
• Occlusive disease in close proximity to the visceral or renal arteries
• Other intra-abdominal pathologies not amenable to standard aortofemoral revascularization

Although some advocate the use of thoracofemoral bypass as a primary procedure, most surgeons consider it a secondary procedure with the previous indications.[1]

Contraindications for a thoracofemoral bypass graft include the following:

• Severe pulmonary insufficiency in a patient who is hence unable to tolerate a thoracotomy
• Unapproachable thoracic aorta

A limiting factor is a prior thoracic operation that precludes or complicates the approach to the descending aorta.

Crawford et al studied outcomes in 41 patients (age, 61 ± 9 years; 54% female; 7% in a hypercoaguable state) who underwent thoracofemoral bypass for occlusive disease.[7]  Mean preoperative ankle-brachial index (ABI) was 0.4 bilaterally. Indications included critical limb ischemia (CLI; 56%), claudication (30%), acute limb ischemia (7%), and combined aortoiliac occlusive disease and mesenteric ischemia (7%). Seven patients (17%) had previously undergone aortofemoral bypass, and 15 (38%) had previously undergone any prior aortic operation. Adjunctive visceral bypass occurred in eight patients (20%).

The postoperative duration of stay in this study was 11 days, and 30-day mortality was 5%.[7] Major complications occurred in 34% of patients. Mean postoperative ABI was 0.9 bilaterally. At a median follow-up of 7 months, five patients underwent some form of reintervention. Estimated 3-year primary limb patency and freedom from major adverse limb events were 80 ± 10% and 70 ± 10%, respectively. Estimated 5-year survival was 93 ± 5%.

Stewart et al, using data from the Vascular Quality Initiative (VQI) suprainguinal bypass module, evaluated outcomes of 154 thoracofemoral bypass procedures performed to treat occlusive disease between 2009 and 2019.[8]  Fifty-nine patients (38.3%) had a prior inflow bypass, and 22 (14.2%) had a prior leg bypass. Indications for the procedure included claudication (42.9%), rest pain (38.3%), tissue loss (12.3%), and acute limb ischemia (6.5%).

Major complications occurred in 31.2% of the cohort, and acute limb ischemia and claudication were associated with increased rates of such complications (acute limb ischemia, 60.0%; claudication, 34.8%; CLI, 24.4%).[8] Survival at 30 days was 95.5%; estimated 1-year survival was 92.7% ± 2.2%. Primary patency was 92.9% at discharge and 89.0% at 1 year. Postoperative major amputation occurred in one patient during the index hospitalization; estimated freedom from major amputation at 1-year follow-up was 97.1% ± 2.2%. Two patients developed in-hospital bypass occlusion, and three patients had occlusion occurring within 1 year; overall freedom from occlusion was 96.8% at 1 year.

Equipment employed in performing a thoracofemoral (thoracic aortofemoral) bypass includes the following:

• Operating table
• Vascular tray
• Thoracotomy tray
• Double-lumen endotracheal tube and bronchial blocker/Univent
• Ability to perform on-table angiography
• Bean bag, pillows, and cushions to facilitate positioning

Anesthesia

The thoracofemoral bypass requires general anesthesia, and most prefer left-lung isolation, though the procedure can be conducted with left-lung ventilation and appropriate retraction. Epidural anesthesia for postoperative pain control is also helpful. An arterial line and, often, a central line can be useful for the procedure as well.

Positioning

The patient is placed in a posterolateral thoracotomy position with the left chest at approximately 45º off the horizontal and with the pelvis in a horizontal position. The left arm is kept anteriorly and supported.[1]

A left thoracotomy (except with sinus invertus) is performed through the seventh, eighth, or ninth rib space. The inferior pulmonary ligament is taken down and the left lower lobe retracted to expose the distal descending thoracic aorta. Standard exposure is done for the femoral vessels. Most surgeons tunnel the graft through a small incision in the diaphragm and pass the graft retroperitoneally to the left femoral vessel.[1]

A standard femoral-femoral tunnel for the right femoral artery is otherwise performed if necessary; alternatively, this portion of the graft can be placed preperitoneally, because of the potential for kinking if it is passed from the left groin to the right. Some authors recommend carrying the intercostal incision across the costal margin or even performing a thoracoabdominal incision.[1, 9]

Most tunnel the graft posteriorly to the kidney, though a technique has been described in which the graft is tunneled anterior to the left kidney. In the author's view, blind tunneling posterior to the left kidney appears to be the simplest approach.

The anastomosis to the descending thoracic aorta is performed in an end-to-side fashion, usually with a side-biting clamp (though proximal and distal clamping of the descending aorta may be necessary). The graft is angled in such a way as to be directed to the previously created tunnel, then clamped after the thoracic aortic clamps have been released. Standard femoral anastomoses are then constructed.[1]  A thoracoscopic method has also been described that involves stapling the thoracic anastomosis.[10]

Complications of thoracofemoral bypass include the following:

• Bleeding (hematoma or pseudoaneurysm)
• Infection
• Acute renal failure
• Dissection
• Distal embolization
• Graft thrombosis
• Myocardial infarction
• Pulmonary insufficiency
• Intestinal ischemia
• Spinal cord ischemia
• Impotence