Overview of Aortofemoral Bypass
Aortofemoral bypass surgery is a medical procedure often used to treat a condition known as aortoiliac occlusive disease, sometimes called Leriche syndrome. This disease affects the blood flow in your body, particularly in the aorta and iliac arteries, the main blood vessels that supply blood to your lower body and legs. It can cause symptoms that include painful muscle cramps in your legs while walking or running (claudication), pain in the legs while resting, and sores or ulcers on the legs that don’t heal because of low blood supply.
Surprisingly, some people with this disease may not show any symptoms at all. When doctors suspect this disease, they often use a test known as an ankle-brachial index which measures the blood pressure at the ankle and in the arm to check for peripheral arterial disease – a condition where the arteries supplying blood to your arms and legs are narrowed.
The use of aortofemoral bypass surgery to manage aortoiliac occlusive disease goes back to the 1950s. However, more recently, doctors are preferring to use a less invasive procedure known as endovascular interventions to restore normal blood flow. In this procedure, a small tube is inserted into the blood vessel to open it up. But, in certain cases when the less invasive methods are not successful or suitable, aortofemoral bypass surgery is still an important option and is often considered the best method for maintaining blood flow in the long term.
Anatomy and Physiology of Aortofemoral Bypass
The aortofemoral bypass procedure is closely related to the structure of certain major arteries in our bodies. To understand this procedure, we need to know a bit about these arteries and how they interact. Let’s break this down.
First up is the aorta, the largest artery in our body. It splits into two branches: the right and left common iliac arteries. These arteries, in turn, divide into two separate arteries each: the external and internal iliac arteries. Final stage of this branching journey are the common femoral arteries, which come from the external iliac arteries.
Now, aortoiliac occlusive disease can happen at any point along these arteries. This disease involves blockages that can restrict blood flow through these important arteries. Understanding the structure and connection of these arteries is vital because this is where blockages can occur, and if a surgeon needs to do a bypass to get around the blockage, they need to know where they can safely stitch (or anastomose) and clamp in the arteries.
Doctors use a method called CT angiography to get a better look at these arteries. This technique uses X-rays and a special contrast material to make the arteries visible on the images and can even generate detailed 3D pictures of these arteries. These pictures can greatly help doctors to diagnose and treat any issue properly.
Why do People Need Aortofemoral Bypass
Aortoiliac occlusive disease is a condition where there’s a blockage in the aorta (the main artery in your heart) or the iliac arteries (which supply blood to the lower half of your body). Laser or surgery might be needed when:
– The disease has caused severe atherosclerosis (hardening of the arteries) causing symptoms
– There’s an acute blockage in the iliac arteries or aorta
– There are severe claudication symptoms (pain and cramping in the lower leg due to inadequate blood flow) despite medicine
– The leg has developed gangrene (a condition that happens when body tissues die) or ulcers which are not healing
– There’s critical limb ischemia (severe blockage in the arteries of the lower extremities, which reduces blood flow)
– There’s erectile dysfunction
Before you have surgery, your physician will probably encourage you to quit smoking, exercise regularly, lose weight, and get the treatment for underlying conditions like high cholesterol, high blood pressure, and diabetes.
Apart from these, the Trans-Atlantic Inter-Society Consensus is a system used to categorize blockages in the aortoiliac, femoropopliteal (a part of the artery in your thigh), and infrapopliteal (referring to anything below the knee) parts of your body according to their severity and complexity. Use of this system helps decide whether the condition would be better treated by surgery or a less invasive technique, like a laser.
The category of the blockages can range from A to D:
Type A – a blockage in one of both iliac arteries
Type B – blockage is less than 3 cm involving the part of aorta below the kidney or in the iliac artery
Type C – blockage in both iliac arteries or in the iliac artery together with the artery supplying blood to the leg or with heavy calcification
Type D – blockage in the part of the aorta below the kidney together with the iliac artery, multiple blockages in the iliac artery, or blockage in the iliac artery if you also have an aneurysm (a weak part of the wall of the artery)
This classification assists physicians to decide if the obstruction should be treated by surgery or other less invasive methods. The less severe cases (Type A & B) are usually treated with lasers, whereas severe cases (Type C and D) are more likely to need surgical bypass. However, sometimes even Type C and D blockages can be treated with lasers, which is also always considered before surgery. This is because laser treatments often involve lower costs, shorter hospital stays, and fewer complications when compared to surgery.
It’s important to remember that each case is unique and the treatment should be decided according to the physical examination, test results, and individual patient factors.
When a Person Should Avoid Aortofemoral Bypass
There are certain circumstances in which a patient cannot undergo an aortofemoral bypass surgery, which is a treatment for blocked arteries. One key reason a person might not be able to have the surgery is if they are too sick or unwell to handle general anesthesia. This means they can’t be put to sleep for the procedure. In such cases, they might be able to have an axillofemoral bypass surgery instead, but this is not discussed here.
There are also factors that don’t entirely stop a patient from having the aortofemoral bypass surgery, but they do mean that they could face more risks or complications. These include having a significant heart disease, having recent strokes, suffering from a recent heart attack, having had multiple abdominal surgeries previously, having retroperitoneal fibrosis (a rare condition that involves the build-up of excess fibrous tissue around organs), or having a horseshoe kidney (where the two kidneys are fused together).
Patients with end-stage kidney disease are also considered high risk. This means that their kidneys have lost almost all of their ability to function properly, and this makes surgeries riskier for them.
Equipment used for Aortofemoral Bypass
For the surgery, the doctor will need a set of special tools that are often used for blood vessel operations. These include a kind of clamp that doesn’t harm blood vessels, loops for handling the vessels, specially designed needle holders, and very precise tweezers. They will also need a kind of tube called a graft, which is used to redirect the flow of blood in a bypass operation. Different companies provide these grafts, and the type available at a given hospital depends on which company the hospital has an agreement with.
The doctor will also need a type of thread known as a suture to connect the graft to the patient’s own blood vessel. During the operation, the patient will be given a medicine called heparin. It’s a standard practice to give heparin before clamping any blood vessels because it helps stop blood clots from forming. Towards the end of the operation, another medicine called protamine is given to cancel out the effects of the heparin.
Finally, at the end of the procedure it’s usually a good idea for the surgeon to have various substances on hand that can rapidly stop bleeding, in case they’re needed.
Who is needed to perform Aortofemoral Bypass?
In order to carry out the operation, the doctor performing the surgery should have enough experience in dealing with blood vessels. This usually comes from special training after they’ve become a doctor, called a fellowship. They also need a team who are skilled in identifying and using the materials needed for the surgery. In simple terms, to make sure you’re safe and the operation goes well, both the doctor and their team need to know what they’re doing and be prepared with the right tools and knowledge.
Preparing for Aortofemoral Bypass
Before having the surgery, doctors usually suggest a few things for patients to do in order to prepare. One of these recommendations is to stop using tobacco products for at least 3 to 4 weeks before surgery. They may also advise incorporating regular exercise into your daily routine.
Just as you need to prepare, the surgeon also has some preparations to make. They will ensure that there is an adequate supply of blood in the operating room in case you need it during the surgery. This is part of standard procedure to ensure your safety.
Also, to further ensure your wellbeing, doctors may perform tests or treatments for your heart before your surgery. This is because studies have shown that these measures can lower the risk of complications during aortic operations.
Finally, it’s common for doctors to give patients antibiotics before surgery. These medicines help to reduce the chances of wound infections after the surgery. They’re another important part of making sure your surgery goes smoothly and you recover as swiftly as possible.
How is Aortofemoral Bypass performed
The medical procedure described here is held while the patient is lying on their back with their arms spread out to 90 degrees. The medical team cleans the patient’s body from the chest down to the knees to prepare for surgery. To prepare for the surgery, the doctors make cuts in both groins to access the main arteries in the legs – called the common femoral arteries (CFAs). They ensure that the ends of these arteries are flexible enough to make clamping possible.
The doctors expose your aorta (the main artery that carries blood from the heart to the rest of your body) by making a cut down the middle of your belly (this is called a transperitoneal approach). In certain cases, they might also favor a cut from the side of your abdomen (retroperitoneal approach) or a horizontal cut. They then move the intestines to one side so they can work on your aorta.
The doctors further dissect the aorta, excluding the part responsible for supplying blood to the kidneys, down to the level of an artery called the inferior mesenteric artery. Tunnels are created in the spaces leading to the cuts in your groins. Medication called heparin is then administered to slow blood clotting, allowing for uninterrupted surgery – the aim is to keep heparin levels in a specific range.
The team puts clamps on the aorta which is then divided. A part of it is cut off just above the inferior mesenteric artery. Considering the remaining part, stitches are put on the lower part of the aorta, and the chosen graft – a piece of blood vessel taken from elsewhere in the body or a man-made tube – is married to the remaining aorta’s upper part. This is typically done using 3-0 or 4-0 running permanent sutures which are durable, high-strength medical stitches.
The surgeons then clean the stitched graft with heparinized saltwater, clamp it, and guide it through the tunnels into the groin cuts. They put clamps on the femoral artery (major artery in the thigh region), make a cut, and if necessary, clear the artery of any blockages. The graft is then married to the femoral artery. After attaching the graft, backbleeding, forward bleeding, and flushing are also done. The same process is repeated on the femoral artery on the opposite side. The surgeon then allows blood flow back into these arteries. But, before doing so, the anesthesiologist is informed because a drop in blood pressure is expected at this point.
The surgeon then closes the body layers around the graft to shield it from the gastrointestinal tract. An ‘omental flap’ – that is shaping a part of the omentum (fat inside the abdomen) to cover up the graft- is needed if the chest cavity cannot be closed completely.
The method described above is typically preferred, because it allows the graft to sit flat and reduce the chances of a future aortoenteric fistula, which is an abnormal connection between the aorta and the gastrointestinal tract. This method also allows increased blood flow to the inferior mesenteric artery. However, for certain individuals with a blocked external iliac artery – an artery that provides blood to the pelvis and lower limbs – a different type of graft connection may be necessary to ensure proper blood flow to the pelvis.
Medical professionals have also tried doing this procedure using laparoscopy, which uses small incisions and a camera, but this is not yet a popular method. There’s also a comparatively newer technique called EndoVascular RetroperitoneoScopic Technique (EVREST), which involves using a laparoscope and does not require sutures or clamps for aortobifemoral bypass surgery, which is the procedure described here.
Possible Complications of Aortofemoral Bypass
Like any operation, surgery can sometimes cause bleeding or infection. Some people might also get complications like wound infection or a build-up of blood under the skin known as a hematoma. Beyond these, other serious complications include heart attack, kidney problems, and difficulties in breathing. Some people might face issues later on, like hernias, which are abnormal lumps, or problems with the blood vessel graft such as blockage and pseudoaneurysms which are false aneurysms caused by blood leak. Some complications involve the connection between the graft and intestine.
For those undergoing aortic reconstruction, half of them might suffer from heart complications, since most of these patients usually have underlying heart issues. This is why it’s so important for medical professionals to check for heart problems before surgery. Death due to heart complications after this type of surgery ranges from 1% to 2.5% in some medical centers.
Kidney problems are another common complication following surgery. This often happens due to a lack of sufficient blood supply after securing the area above the kidneys during the surgery, or due to issues in the kidney arteries. The risk of this complication can be reduced by understanding the patient’s body structure and planning the surgery carefully.
Also, up to 30% of patients might face blockage in graft limb, a type of blood vessel graft, after the operation. This usually happens due to abnormal tissue growth in the inner lining of blood vessels or diseases that obstruct blood flow. This complication is more likely in younger patients, women, those undergoing bypass surgery outside the normal anatomic pathway, and those who continue to smoke after surgery.
Another complication is anastomotic pseudoaneurysm, which happens in 1% to 5% of people. This complication generally arises due to weak spots near the suture line which could be due to infection. If the lump becomes larger than 2 cm, or half of the graft’s width, or if the graft itself is infected, it would usually be recommended to repair the graft.
Aortoenteric fistula, a rare complication that involves a connection forming between the graft and intestine, can be life-threatening, with a mortality rate of about 30%. This usually happens due to the erosion of the stitch line on the aorta through the intestine. In order to detect it, CT scans with injected dye and procedures to visualize the upper digestive tract can be helpful. In cases where it’s found, emergency exploratory surgery would be required to remove the graft, clean up the infection, repair or remove the damaged part of the intestine, and replace the graft or create an alternative pathway for blood flow. Despite successful surgeries, this complication can still lead to high mortality rates.
What Else Should I Know About Aortofemoral Bypass?
It’s important to note that after a procedure to reopen blocked vessels (revascularization), many patients maintain good blood flow for about 5 years with rates typically ranging from 64 to 95%.
An aortobifemoral bypass is a surgery that improves blood flow to your legs by bypassing blocked arteries. This surgery has a success rate of 80% and usually helps to keep arteries open and symptoms relieved for about 10 years. After the surgery, patients often find relief from pain, especially when resting and the pain is also significantly less when walking. If you’re a smoker, quitting before and after the bypass surgery can improve your results even further.
