Overview of Popliteal Aneurysm Repair
Popliteal artery aneurysms are the most commonly occurring type of aneurysms that happen outside of the heart. They are more prevalent in men than in women; 7 out of every 100,000 men and 1 out of every 100,000 women experience these aneurysms. An aneurysm in this context refers to an abnormal bulging or expansion of the popliteal artery – an artery located behind the knee. This happens when the artery wall weakens due to the damaging action of immune cells.
To understand if the popliteal artery has become aneurysmal, we measure its size. If the diameter of the artery is 1.5 times larger than a normal section nearby, it is considered an aneurysm. Half of the patients who suffer from this condition can have it in both the arteries behind their knees. Plus, 30 to 40% of the patients may also develop an aneurysm in their abdominal aorta – the main artery that runs down the abdomen.
An exciting fact about these aneurysms is that their growth rate gradually increases in direct correlation to their size. In simpler terms, the bigger the aneurysm, the faster it grows. High blood pressure or hypertension has been identified as the leading factor that accelerates this growth. These aneurysms rarely rupture. However, clot formation or blockage can lead to deficient blood flow, and this is a common issue related to these aneurysms. This makes the risk of losing a limb very high.
It is possible to identify these aneurysms through a physical examination where the doctor will look for a noticeable pulse and mass behind the knee. Other sophisticated imaging techniques such as ultrasound, CT scans, MRI scans, or angiography (procedure used to see your blood vessels) may also be used to get a concrete diagnosis.
Anatomy and Physiology of Popliteal Aneurysm Repair
The popliteal artery is an extension of the superficial femoral artery, starting at the tendon insertion point of the adductor magnus muscle. This muscle is located in the inner thigh. The popliteal artery travels through an area at the back of your knee called the popliteal fossa. It then splits into two branches: the anterior tibial artery and the tibioperoneal trunk when it reaches the level of the tibial tuberosity, a noticeable bump on the top front part of your shin bone.
Why do People Need Popliteal Aneurysm Repair
If you are experiencing symptoms linked to a popliteal artery aneurysm – a bulging and weakened area in the popliteal artery, located in the leg behind your knee – getting repair treatment could be necessary. The primary symptom is lower leg ischemia, which is when blood flow to your leg muscles is reduced. This typically happens due to a blockage caused by blood clots forming within the aneurysm.
The symptoms can vary, starting with claudication, which means that you get leg pain when walking, moving to an acute limb ischemia, a more severe condition where blood flow to one of your limbs is blocked entirely. Sometimes, the aneurysm can expand so much that it starts pressing against near structures, leading to leg swelling or blood clots in veins deeper inside. It’s important to note that popliteal artery aneurysms very rarely rupture, which is not like aneurysms that form in other body parts.
Even if you aren’t suffering from any symptoms, you might still require repair treatment if the aneurysm is larger than 2 cm in diameter and you’re generally in good health. This is a preventative measure to stall possible complications down the line.
When a Person Should Avoid Popliteal Aneurysm Repair
People who are not experiencing any symptoms but have a blood clot in the popliteal artery (the main artery behind the knee) can be watched closely for any signs of worsening symptoms. The popliteal artery is important because it provides blood flow to the lower legs. Sometimes, these symptoms can be a sign of ischemia, which means the tissues in the leg are not getting enough blood and oxygen.
Patients who have poor tibial runoff, meaning that blood flow through the tibia (the major bone in the lower leg) is not good, might not be best suited for a procedure to fix the popliteal artery. This is because the surgical outcomes might not be as good if the blood can’t flow well through the leg after the repair.
Equipment used for Popliteal Aneurysm Repair
For an open repair surgery, your doctor will need certain equipment. This includes:
* A well-equipped operating room
* Protective clothing like a mask, eye shield, surgical cap, sterile gown, and gloves
* Materials to clean and disinfect the skin over the surgical area
* Sterile covers placed around the surgical site to maintain a clean environment
* An ultrasound machine to get images of the body’s interior
* Intravenous heparin, a medicine that prevents blood clotting during surgery
* A combination of electrical tools and standard surgical instruments such as scalpels, needle holders, tissue forceps, scissors, and different types of clamps
* Various kinds of stitching material and ties as per the surgeon’s requirement
* A doppler, a device used to check blood flow and clotting during the operation.
For an endovascular repair procedure, the following tools are needed:
* An angiography suite which includes a c-arm, a special type of x-ray machine
* A device for injecting dye contrast, to create clearer images of the body’s insides
* Protective clothing similar to those used in open repair
* Materials for skin cleaning and sterile drapes just as in open repair
* An ultrasound machine and intravenous heparin like in open repair
* A local anesthetic to numb the surgical area
* A micro puncture access kit, to make small, precise surgical incisions
* Different types of arterial sheaths, catheters, and wires for blood vessel work
* A flexible, self-expanding covered stent (a tube placed inside a blood vessel to keep it open) as per the surgeon’s choice
* A closure device identified by the surgeon to secure the surgical wound after the operation.
Who is needed to perform Popliteal Aneurysm Repair?
When you need to have an open repair surgery, there are several people involved to make sure everything goes smoothly. First, there is a surgeon, a doctor who performs the operation. Next, there is an anesthesiologist, a doctor who makes sure you don’t feel any pain during the procedure by putting you to sleep or numbing the area. There’s also a first assistant, who helps the surgeon during the operation. Lastly, nursing staff, including a circulator and scrub tech, are present to assist and ensure everything goes safely. A circulator is a nurse who assists the surgical team by getting things they need during surgery, and a scrub tech, also known as a surgical technician, helps the surgeon and first assistant by handing them surgical instruments.
For an endovascular repair procedure, which is a less invasive procedure performed inside your blood vessels, the team is mostly the same but with one more addition – a radiology technician. This person operates the imaging machines, which provide the surgeon with a picture of what’s happening inside your body, helping them guide their instruments safely and accurately.
Preparing for Popliteal Aneurysm Repair
There are two main ways to treat popliteal artery aneurysms, a swelling in the popliteal artery located behind your knee. These are open surgical bypass and placing a stent inside the vessel. These options are both under continuous discussion as experts try to decide which is best. A study found that the stent, a small mesh tube used to treat narrow or weak arteries, had fewer complications related to the wound and a shorter stay in the hospital. However, the success rate of the stent working properly was slightly lower after three years. The stent is typically used for patients who choose to have surgery and are at high risk of complications during or after the procedure. The best treatment option, whether surgical bypass or stent, depends on the patient’s overall health condition, the exact shape and location of the aneurysm, and how bad the blood flow is affected.
For the open surgery, planning is very important. Doctors must carefully look at imaging, like x-rays or scans, to decide where they should make the cuts (or incisions) for surgery, and to decide what type of material they should use for the bypass. The type of incision depends on the size and shape of the aneurysm. The most common cut is made on the inner side of the knee, best for smaller or evenly shaped swellings. Larger or irregularly shaped swellings, or those causing symptoms because they are pushing against other structures, are best approached from a cut made behind the knee. Your position during the surgery will depend on where the surgeon needs to make the incision.
For the stent procedure, doctors must carefully examine the vessel where the stent will be placed. Ideally, there should be a certain length of normal, healthy vessel both before and after the aneurysm where the stent will be positioned. Over-bending (or ‘kinking’) should also be avoided as this is likely to cause complications with the stent. Successful long-term treatment with a stent in the popliteal artery depends greatly on how good the blood flow is below the aneurysm. One study found out that when the blood flow in the leg was good, the stent worked more successfully. So, this procedure may not be the best option if the patient has poor blood flow in the leg. Additionally, the patient must take two types of blood-thinning medication, which should be discussed before the procedure. During the procedure, the patient lies face-up on a table specially designed for these types of treatments.
How is Popliteal Aneurysm Repair performed
In the Open Repair, Medial Approach surgery, the surgeon first cuts open your leg above the knee. They also make a cut below the knee, near the inside part of your shin bone. A vein, called the greater saphenous vein, is then removed. This is done to use it later in the operation.
The surgeon then focuses on the knee area. They cut a space between two muscles, necessary to reach the popliteal fossa, an area at the back of your knee. The surgeon finds and isolates the artery in the knee, which is a blood vessel that transports blood away from the heart. They do the same thing with the popliteal artery below the knee and create a passageway through the muscles in your leg.
Blood-thinning medication, called heparin, is given to you to prevent unwanted blood clotting. The removed vein is threaded through this passageway. Clamps stop the flow of blood to the artery near and inside the knee, and the artery ends are connected using stitches.
A similar process is done with the artery below the knee. The connections, or anastomoses, between the arteries and the vein are checked with a special tool called a Doppler to make sure that blood is flowing properly. If needed, additional steps may be taken to prevent any excess blood flow from entering the aneurysm sac (a bulge in the artery). Finally, your wounds are cleaned and stitched closed.
The other surgical approach, called Open Repair, Posterior Approach, also involves making cuts but at the back of your knee. Either the small saphenous vein or the greater saphenous vein, depending on their size, is removed and saved for later. The surgeon then finds the artery and cleans it – this involves isolating the artery where it’s healthy, on either side of the aneurysm. Once again, you’ll receive a blood thinner, and clamps block blood flow at the artery’s ends, allowing the original vein to be connected. The Doppler checks the blood flow, any bleeding is stopped, and the wounds are closed.
In the Endovascular Repair procedure, different steps are taken. Firstly, the surgeon inserts a small, thin tube into an artery in your leg, away from the aneurysm. They then take pictures to understand the layout of your blood vessels. They slide a thin, soft wire through the aneurysm and into a smaller blood vessel in your foot. A stent graft, which is a synthetic tube, is then placed over this wire to support the artery’s walls. The surgeon uses a balloon to make sure the stent fits correctly, and repeat checking is done to confirm that blood is flowing to the foot. To stop the effects of the blood thinner, a medication called protamine is usually given. After securing this, the surgeon removes the tube and takes steps to stop any bleeding from the puncture site.
Possible Complications of Popliteal Aneurysm Repair
When an enlarged blood vessel in the back of the knee (known as a popliteal artery aneurysm) is repaired with open surgery, there can be some complications. These might include problems with the wound, the sac that contains the aneurysm getting bigger, the vein graft (a piece of vein taken from elsewhere in the body to bypass blockages) becoming an aneurysm itself, or graft failure, which means the graft didn’t work as expected.
When a popliteal artery aneurysm is fixed using a less invasive process called endovascular repair, similar complications can occur. These might include complications at the site where the doctor inserted the tools (like bruising or a ‘pseudoaneurysm’, a false aneurysm where the blood is contained by the surrounding tissues), the stent (a small tube inserted to keep the artery open) might get twisted, move, break, form a blood clot or endoleak (leakage of blood into an aneurysm sac after endovascular repair).
What Else Should I Know About Popliteal Aneurysm Repair?
An aneurysm in the popliteal artery, located behind your knee, is quite rare. However, if it does occur, it could put the impacted leg in danger. An aneurysm is a weakening or bulging of an artery wall. If you are experiencing symptoms or the aneurysm is larger than 2 cm, it may be necessary to get it repaired.
There are two main types of repair: endovascular and open surgery. Endovascular repair is less invasive, meaning it uses smaller incisions. This usually reduces the amount of time you need to stay in the hospital and lessens the chance of wound complications. On the flip side, the benefits of this method might not last as long as open repair. Open repair, which involves a larger incision, might offer longer-lasting benefits but could lead to a longer hospital stay and higher risks.
There is no one-size-fits-all approach, so it’s critical to have a discussion with your doctor about the best option for you. Your doctor will consider your unique situation and help you weigh the risks and benefits of each repair so you can decide together which option is right for you.