Conditions & Procedures
- Endoluminal Treatment of AAA
- Standard Endoluminal Graft
- Fenestrated Graft
- Carotid Angioplasty and Stenting
- Endograft for Thoracic Aneurysm & Dissection
- Varicose Vein Surgery
- Renal Artery Angioplasty and Stenting
- Peripheral Angioplasty
Standard Endoluminal Graft for Abdominal Aortic Aneurysm (AAA)
The Zenith® endovascular graft is the culmination of a worldwide collaboration of experts whose experience and developments were compiled, resulting in an endovascular prosthesis designed to treat infrarenal abdominal aortic aneurysms. The device is made of stainless steel, self-expanding Z-stents and polyester fabric. It has an uncovered stent with barbs (for fixation) that extend into the suprarenal aorta and is modular in design and allows for disparity in the length and diameter of the iliac arteries that are incorporated into the repair. A prospective study contrasting endovascular and open surgical patients was completed in 2002 and resulted in US Food and Drug Administration approval of the device for commercial sale within the USA.
Although long-term data from the trial are still being evaluated, the worldwide experience with this device and its predicate devices has allowed for certain conclusions to be made with respect to performance expectations and aneurysm sac behavior. The periprocedural mortality in healthy patients with anatomy meeting the device instructions for use should be under 2%. The expected risk of endoleak (mostly Type II) was 7.4% at 12 months and 5.4% at 24 months. Migration (based on the reporting standards for endovascular aneurysm repair recommended by the vascular surgical societies, published in the Journal of Vascular Surgery in 2001) was not seen in any patients over 12 months.
The majority of the aneurysms shrink at 1 and 2 years, and any patient exhibiting aneurysm growth had a detectable cause and required treatment. Coupled with European and Australian data, including several device explants, the device integrity issues are limited to barb separation (which has about a 2% incidence and appears incidental in the US trial) and suprarenal stent detachment (six cases detected worldwide). In order to address the latter problem, a design alteration was implemented with a double suture attachment, significantly increasing the tensile strength of the device. No separations have been noted since the change instituted at the conclusion of the US trial. Similar good results have been reported with the Medtronic Endurant endograft as well as the Gore C3 aortic device. Together these form the three most common aortic stent-grafts that are in use in Australia and all of them are used in our practice, depending on which device is most suited to patient anatomy.
Fenestrated Zenith Graft for AAA
This graft was specifically designed for aneurysms which were close to or involved the renal arteries.It was developed in Australia by vascular surgeons and the Cook Research Team in Perth. If a standard graft was deployed in this situation then either it would not seal the aneurysm adequately or it would fail after a few years. Previously these aneurysms had to be treated by major open surgery but now they can be very well treated with endovascular techniques. We are very fortunate in that our surgeons can call upon the experience of Dr. Alan Bray who although now retired had employed this technique for a number of years and is a proctor for these procedures. Over 2,000 fenestrated grafts have now been deployed world wide, with excellent results. Thus it is not experimental, but the degree of difficulty and hence risks to the patient are higher than the standard Zenith repair. The risk of death or serious disability is still much less than open surgery as these aneurysms have a higher risk for open surgery as well. Hence, you do not have to end up with major open surgery, just because your aneurysm is near the renal arteries and not suitable for a standard endograft. Also, each fenestrated graft is specially made for each individual aneurysm as it is important that all the holes(or fenestrations) in the graft fit the precise anatomy of the visceral artery origins in each aneurysm. Hence, the graft is not TGA approved,but it is made of the same material as the standard TGA approved Zenith graft. It also takes 6-8 weeks to have each graft manufactured This can be an issue for patients presenting with very large aneurysms, as these are usually treated promptly.
Zenith® Fenestrated AAA Endovascular Graft
The video clip shows the various steps involved in operation; as you can see there are a number of extra steps involved in cannulating the renal arteries and sometimes, the superior mesenteric artery.This can take an extra few hours in difficult cases.However, as far as the patient is concerned it is much the same as the standard graft in that there are only needle punctures in both groins. The post-operative course is much the same, but may take a few extra days to be back to normal due to the lengthier procedure.The course of the aneurysm sac and graft are followed closely with ultrasound to be sure that everything settles properly.This will be continued with a vascular ultrasound scan each year.
Endograft for Thoracic Aneurysm and Dissection
The technique for excluding thoracic aneurysms is similar to that for abdominal aneurysms but the surgical alternative is much more morbid than the endoluminal technique, necessitating a thoracotomy (large cut in the chest in between the ribs) and some form of left heart bypass with risks of paraplegia (loss of nerve control of lower limbs) and death, prolonged ICU stay, etc. Endoluminal repair is carried out percutaneously most of the time and while the complication rates are higher than for abdominal aneurysms, they are significantly less than for open repair. Paraplegia can still occur in about 5% of cases, especially if the aneurysm is a large one, necessitating extensive coverage of the thoracic aorta. Thoracic Dissection refers to a separation of the layers of the aortic well with blood being forced down a false channel within the aortic wall, thereby tearing the lining of aorta from its muscular wall and creating what looks like a double channel in the aorta. The problem with this is that it can result in reduced flow or blockage of arteries to important end organs such as the kidneys and the liver, small bowel. Sealing the ‘entry point’ (the beginning of the tear) with a stent-graft can reverse the pathological process and allow healing and remodelling to occur.
Carotid Endarterectomy/Carotid Angioplasty and Stenting
Carotid artery disease is a major risk factor for disabling stroke. This results from embolization (dislodgement and movement along the artery) into the brain of plaque material and thrombus (clot) from disease build-up in the carotid artery. Carotid revascularization by endarterectomy or angioplasty and stenting has been shown to be more effective than medical treatment alone in preventing disabling strokes in symptomatic severe and moderate carotid stenoses(areas of narrowing) as well as in asymptomatic severe stenoses.
The most recent large studies suggest that surgical endarterectomy should be the procedure of choice in patients with accessible disease who are in reasonably good health. These are associated with the lowest periprocedural stroke and death rates. There will of course be an incision in the neck that will heal to a near-invisible scar and there is also a higher change of cranial nerve injury, mostly temporary. For some patients, carotid endarterectomy is not a very good option because the location of the stenosis, or the patient's overall health, may make surgery too risky.
Carotid angioplasty and stenting shows promise in the treatment of carotid artery disease for patients who may not be in good enough health to undergo surgery -- such as those with severe heart or lung disease; those who have had neck operations or radiation for neck tumors; and those who have already had carotid endarterectomies. Since cerebral protection devices (microfilters) have been available, angioplasty has become near equivalent to endarterectomy as the risk for embolisation (debris floating to the brain) has been considerably reduced. In carotid angioplasty, a catheter (a long hollow tube) is inserted in the groin artery and threaded through the arteries to the narrowed carotid artery; a microfilter is deployed above the narrowing to stop particles passing to the brain. A tiny balloon at the end of the catheter is inflated to open the narrowed area, and a metal stent (wire-mesh tubular scaffolding) is inserted to keep the artery from narrowing again.
Patients are awake during the procedure, and are usually discharged from the hospital the following day. Most patients are able to resume normal activities when they ge home. The advantages are:
- Local instead of general anesthesia
- Fewer surgical complications such as nerve injury, hematoma (bruising) and wound infection
- Shorter operation
- Less discomfort
- Smaller incision
- Shorter recovery time
- Maintain anti-platelet agents during procedure
- Good long term results are emerging
- Ability to treat narrowed arteries that are hard to reach or difficult to treat with surgery
Varicose vein surgery and endovenous therapy
To perform vein stripping, your physician disconnects and ties off all major varicose vein branches associated with the saphenous vein, the main superficial vein in your leg. Your physician then removes the saphenous vein from your leg. A procedure, called small incision avulsion, can be done alone or together with vein stripping. Small incision avulsion allows your physician to remove varicose veins from your leg using hooks passed through small incisions. In a similar procedure called endovenous thermal ablation, your physician inserts a laser fibre or a radiofrequency catheter into your saphenous vein; this is then used to ablate the saphenous vein using heat generated by the laser or by radiofrequency. The vein eventually scars off and the result is equivalent to that obtained by stripping. Although these procedures sound painful, they cause relatively little pain and are generally well tolerated. Your vascular surgeon will advise you regarding which procedure is the best for your particular situation.
Renal Artery Angioplasty and Stenting
RAS is a condition in which the artery that supplies blood flow to the kidney becomes narrowed and eventually blocked. Atherosclerosis is the primary cause of RAS (60-70%). Also known as plaque, this is a buildup of cholesterol in the artery. Atherosclerosis is most common in people over the age of 50 as well as in those with vascular risk factors. Fibromuscular Dysplasia (FMD) is another cause that accounts for 30-40% of RAS cases. This is a disease in the muscular lining of the artery that causes narrowing of the renal artery. This occurs mostly in younger women. The cause of FMD is unknown. FMD is successfully treated with Renal Artery Angioplas. The symptoms include high blood pressure that does not respond to blood pressure medication and deterioration of kidney function because the kidney is unable to excrete toxins from the body. If the kidney is starved of blood flow, it will be unable to filter toxins from the body. Decrease in blood flow can cause permanent kidney damage that may lead to kidney failure. When the kidney(s) sense a reduction in blood flow, a hormone called renin is secreted that further raises blood pressure. This results in a condition known as renovascular hypertension.
The following tests can be used to diagnose renal artery stenosis:
- Duplex ultrasound
- CTA—Computed Tomography Angiography
- MRA—Magnetic Resonance Angiography
During the angiogram you will be placed on an X-ray table and an antiseptic solution will be applied to your groin area. You will receive a local anesthetic that will numb the skin at the groin. Then a thin catheter will be inserted through the skin into your artery in order to see the blood flow to your kidneys. An X-ray dye will be injected to visualize the artery better and determine if a blockage is present. The blood flow to the right and left kidney will be examined during the angiogram.
What is Renal Angioplasty?
If a blockage is found, a catheter will be inserted into the renal artery. This catheter has a balloon on the tip of the catheter. The balloon is inflated and deflated causing the plaque to be compressed along the wall of the artery. This opens the artery and restores blood flow to the kidney. A small metal coil, called a stent, may be placed in the artery to hold the artery open, thus preventing a blockage in the future. A stitch or plug is usually placed to seal the puncture site after the procedure. After the angiogram and angioplasty, you will be kept overnight in the hospital, and then you will be discharged home the following morning. You should notify your doctor if you experience; a lump bigger than the size of a walnut in your groin area, a fever; extreme pain or discomfort in the groin area, redness or drainage at the groin site.
Peripheral (Lower Extremity/Upper Extremity) Angioplasty
At the outset, you will be covered with a sterile sheet. A local anesthetic is injected into the skin in the groin to make it numb. A sheath is then inserted into the artery of your arm or leg. The doctor works through this sheath and inserts catheters into the target arteries. When the X-ray dye is injected into your arteries, the vascular surgeon views this on the television monitor, and a permanent record is kept on hard disk or CD-ROM. Once the narrow area (stenosis) is identified in your artery, the doctor will pass a tiny guiding wire across it, over which a second catheter will be passed through the stenosis in your artery. This catheter carries a deflated balloon and special markers, which can be seen under X-ray in order to help place the balloon in the exact position needed. The balloon is then inflated. This opens up the narrowed artery and cracks the plaque or compresses it "like footprints in the snow"; this could cause you some pain. The balloon inflation may be from one to three minutes and could be inflated several times until the artery has been opened optimally.
If the open artery does not look ideal, the doctor may decide to insert a stent; which is a small wire-tube scaffold. This stent is either carried on a balloon catheter, placed in the culprit area and inflated or is self expanding and is deployed across the the ballooned area to hold it open. The metal mesh expands or is expanded by a balloon and is pushed against the plaque and, like a scaffold, is left inside the artery. All patients who have peripheral angioplasty should receive one aspirin a day, and if a stent is implanted patients also take another medicine that makes platelets less sticky. These blood thinners are important to prevent a clot forming on the stent. The procedure will usually take 45 to 90 minutes. The sheath will either be taken out and the puncture site sealed with a stitch or plug or it could be left in your groin for 3 to 4 hours. It is then removed with pressure applied by Recovery room nurses or by a mechanical pressure device. This ensures that the puncture site is sealed. After the procedure you will be observed in a Recovery unit and then overnight on the ward. You will be encouraged to drink fluids since that helps flush the X-ray dye through your kidneys.