Sunday, May 16, 2010

Radial vs Femoral Access - Closure Device Market faces serious impact

While the US is slow to adopt this procedure it is somewhat inevitable that serious impact will be felt by companies involved in the vascular closure market....


T
he Body's Highway
Interventional medicine, or catheter-based therapy, utilizes the body's circulatory system as a "highway" -- and avoids open surgery by threading catheters into arteries and delivering medicine and devices to the affected areas from the "inside-out".

This highway can be accessed by several "on-ramps": the femoral artery in the groin, the radial artery in the wrist and the brachial artery in the elbow.

tip of ordinary hollow catheter
hollow catheter tip

The Femoral (Groin) Approach
When attempting to access the coronary arteries to clear a blockage with a balloon, or place a stent to hold the artery open, the most often used entry point to the circulatory system has been the femoral artery. A small puncture is made with a hollow needle, which then allows a long tube, called a catheter, to be threaded into the femoral artery, up and around the aorta and into the coronary arteries. This femoral approach, sometimes called the Judkins technique (after
Dr. Melvin Judkins who invented it in the 1960's) is the standard way in which most catheter-based procedures are done in the U.S.

However, there are some limitations to the femoral approach. The femoral or nearby arteries may be diseased and will not allow a catheter to pass easily. Sometimes a patient is overweight or obese, and the femoral artery is buried deep underneath the fatty tissue, making it hard to access, and then equally hard to compress after the procedure -- a necessary step in stopping the bleeding. In some cases, bleeding that is not immediately visible to the eye can occur in a backwards fashion into the body cavity -- this can be seen as a discoloration, like a bruise, that expands and must be treated. The possibility of involvement of the femoral nerve also exists. These types of complications are small in number, often quoted at 3%.

Invention of the Radial Technique
In the late 1980's, a French-Canadian physician, Dr. Lucien Campeau, started using the right radial artery, which is located in the wrist, as an entry point for diagnostic catheterizations. While the radial artery is slightly smaller than the femoral, it is still large enough to allow most catheters to traverse the distance to the coronary anatomy. In fact the radial artery was initially harvested and used in coronary artery bypass grafts.

By 1992 a group in Amsterdam, headed by Dr. Ferdinand Kiemeneij, had begun exploring ways to use the radial artery for interventional procedures, such as delivering balloons and stents. They were somewhat limited by the early equipment, but as catheters and stents became lower profile, thinner and easier to manipulate, the ability of physicians to use the radial artery increased. Most devices today can be delivered successfully using the radial artery.

Advantages of the Radial Approach
Most of the disadvantages of the femoral technique are nonexistent in the radial, also called the transradial approach. Even in obese patients, the radial artery is close to the skin surface, making the initial needle puncture simple and straight-forward. For the same reason, when the procedure has been completed, a short compression of the radial artery can stop the bleeding (achieve hemostasis) -- even when the patient has been aggressively anticoagulated with medicines to keep blood clots from forming, more and more common in the modern cath lab. Should any bleeding occur, it can be seen immediately. Finally, unlike the proximity of the femoral artery to the femoral nerve, the radial artery is not close to a major nerve, so the likelihood of "nicking" a nerve during the procedure is very low.

While complications are less common with the radial technique, the advantage experienced by all radial patients is that there is no longer any need to lie flat and still for 4-6 hours, or to experience what is sometimes a painful manual compression of the artery to curb the bleeding. Patients leave the catheterization lab and are able to sit up and walk almost immediately. Because of the simpler healing process for the arterial puncture in the wrist, certain patients may also be discharged home without having to spend the night.

The progress in the treatment of coronary artery disease has evolved to the point that when you compare heart bypass surgery from two decades ago with stenting done today via the transradial approach, what was a 4 hour major open heart operation, with general anesthesia, a week or more in the hospital and months of recovery, can now in some cases be performed as an outpatient procedure.

Is the Radial Approach for Everyone?
There are a few prerequisites for patients to be a candidate for the transradial approach. The first is confirmation of a dual, or "protected", blood supply to the hand. The radial artery loops around the hand and joins the ulnar artery. Both arteries supply blood to the hand and fingers. It is precisely this dual blood supply that makes the radial technique safe. Should the radial artery close up (a complication seen in a small percentage of cases) the clinical result tends to be benign, because the ulnar artery continues to function.

The first step a cardiologist takes in deciding on the radial approach is an Allen test to assess that both radial and ulnar arteries are functioning normally -- a simple test that can be done by compressing the arteries by hand at bedside or in the doctor's office. If they are not normal, then the femoral approach is preferred. Some other contraindications exist, such as the need to use larger devices during the angioplasty, pre-existing bypass grafts in certain areas or tortuous vessels that may prevent the catheter from navigating to the coronaries from the arm. About 30-40% of patients are not candidates for radial access.

diagram of radial and ulnar arteries

While the complication rate with the radial approach is extremely low, there is always some risk with any medical procedure. It is important for patients to discuss the risks and benefits of the femoral vs. radial approaches, as these can vary for each individual.

Limited Utilization in the United States
The more frequent reason that patients are not offered the radial approach is that only a relatively small percentage of interventional cardiologists in the U.S. are trained in the technique. Parts of Europe and Japan do 40% or more of their cases using the radial artery, but in the U.S. estimates are in the low single digits -- although those U.S. cardiologists and radiologists who have learned the radial technique tend to use it for many, if not most, of their patients.

The reasons for this low penetration are several: lack of economic incentive due to the reimbursement structure, lack of patient awareness that this alternative exists, and lack of trained cardiologists. The situation, however, is changing. More and more practices are beginning to see the advantages in lower complication rates, increased patient satisfaction and even cost-savings (complications can be expensive to manage).

The femoral approach has been the gold standard for many years. Moving to the newer radial technique requires specialized training and advanced skills. Training opportunities are increasing as computer simulation models are being developed and a number of hospitals, both in and outside of the U.S. are now offering programs and mentorships. Current signs point to the increasing use of the radial technique in the U.S.

Interested in TransRadial Training? Click Here

Cost-Effectiveness of the Radial versus Femoral Artery Approach to Diagnostic Cardiac Catheterization


Cardiodex

CardioDex is a privately owned company engaged in the development, manufacturing, and marketing of devices for arterial access site closure, following catheterization procedures.

CardioDex has developed state-of-the-art disposable devices; EpicloseTM and EpicloseTM Plus that do not use any glue, collagen, suturing or other foreign materials thus no residual material is deposited in the patient’s body.
CardioDex's products expedite arterial closure through hemostasis. The process relies on familiar balloon inflation/deflation techniques, which apply selective pressure precisely over the puncture site. The products do not require exchange of the introducer sheath.
CardioDex's products address both the diagnostic and therapeutic markets.

New treatment method in sight in cardiac surgery

A joint clinical trial conducted by the University Hospital and the University of Gothenburg, Sweden, found that an element in human blood, fibrinogen, is likely more vital to the blood's clotting ability in connection with heart surgery than previously considered. If the patients also receive a dose of fibrinogen prior to the procedure, this reduces the risk of haemorrhage during and after surgery. These results may open the door to new strategies in reducing bleeding complications in cardiac surgery.

Each year over 7,000 Swedes undergo open-heart surgery, most commonly a coronary artery bypass or a valve replacement. It's a major procedure during which the heart and lungs are stopped and their functions are temporarily replaced by a heart-lung machine, or CPB pump.

'But the use of a CPB pump has negative effects on the blood's clotting ability, and those effects last a few hours after the operation,' says Dr Martin Karlsson at Sahlgrenska Academy at the University of Gothenburg, author of the thesis. 'This leads to a risk of bleeding. It's unclear why certain patients have more problems than others, but several factors may be involved.'

Fibrinogen is one of the most important coagulation proteins in our blood, and the thesis shows that the amount of fibrinogen in the blood is more important than previously thought to ensure clotting after heart surgery.

'We found that the amount of fibrinogen in the patient's blood immediately prior to bypass surgery is directly related to how much the patient bleeds afterwards, and also to the need for blood transfusions after surgery. As a rule, patients with lower levels of fibrinogen in their blood prior to surgery bleed more, even if they have levels that were previously perceived as normal and sufficient.'

In one part of the trial, bypass patients with low levels of natural fibrinogen in their blood were pre-treated with fibrinogen concentrate before the operation. This reduced the amount of bleeding and the need for transfusions during and after surgery compared with a control group, and the pre-treated patients showed no signs of side effects.

'Treatments such as this have never been tried on patients before, and this trial was only a pilot study, with a small number of patients,' Karlsson explains. 'So it's too early to draw any real conclusions, but the results are promising and larger trials have already begun.'

Karlsson hopes that if the results of the pilot study can be confirmed, then fibrinogen concentrate could be used as a preventive therapy for patients about to undergo a surgical procedure and in other instances where the risk of haemorrhage is high. This would offer a new treatment option for the large number of patients undergoing cardiac surgery each year, possibly also for other surgical procedures.