NEW YORK, May 15 -- Most patients who undergo diagnostic angiography or a percutaneous coronary intervention in the U.S. face hours and hours post-procedure -- often including an overnight stay -- lying flat on their back with a sandbag putting pressure on the groin.
That's because about 98% of catheterizations done in the U.S. are performed through the femoral artery, which requires that patients be confined to a hospital bed after the procedure to assure that hemostasis will be achieved.
The other 2% of procedures are performed using transradial access through the wrist. It carries a lower risk of bleeding complications and a shorter recovery time -- patients can often be up and walking minutes after the procedure.
The main advantage to the transradial approach is a reduction in bleeding.
A study published in 2008 in the Journal of the American College of Cardiology: Cardiovascular Interventions showed that bleeding complications associated with percutaneous coronary interventions were reduced by 58% with the transradial approach compared with femoral access, a finding consistent with other research.
In that study, the absolute risk of bleeding was 1.83% with the femoral approach and 0.79% with the transradial approach.
One reason for the reduced bleeding risk is that the radial artery is close to the surface, so it's easier to close the access site. Specially designed pressure wristbands are used in some circumstances, but gauze and an elastoplast bandages work as well.
The ease with which hemostasis is achieved is particularly important for women, who have higher rates of bleeding than men, for the obese -- in whom access to and compression of the femoral artery is more difficult -- and for patients who require high levels of anticoagulation.
According to Sunil Rao, M.D., assistant professor at Duke and director of the cath lab at the VA Medical Center in Durham, N.C., patients undergoing a transradial procedure can remain fully anticoagulated.
U.S. Interventionalists Reluctant to Switch
So why, then, has transradial access failed to take hold in the U.S. when 40% to 50% of catheterizations are being done this way in Canada, Europe, and Asia?
The reasons revolve around training, habit, and time, and include a reluctance among physicians who are used to performing femoral procedures to learn a new technique.
"There's a lot of inertia on the part of practicing physicians," Dr. Rao said. "They like doing things the way they do them."
Dr. Rao started using the transradial approach days after he finished his fellowship in 2004. Having done only three during training, he was forced to use the radial artery for an older woman whose aorta was completely occluded.
From that point on, he said, he insisted on using the radial approach at least once every time he was scheduled in the cath lab so he wouldn't be caught off guard -- or out of practice -- again.
Now, he performs about 80% of procedures through the wrist.
Dr. Rao estimated that it takes about 30 to 50 procedures for someone who is used to the femoral route to become comfortable with transradial access. Other interventionalists gave similar estimates.
But John Coppola, M.D., chief of cardiology and director of the cath lab at St. Vincent Catholic Medical Centers in New York, said it would take about 500 to completely master the technique and to see all the unusual anatomical variations.
In general, he said, cardiologists outside the U.S. spend much more time in the cath lab than American interventionalists, so logging that number of procedures wouldn't take as long as it would in the U.S.
"Your first 20 cases are potentially going to be somewhat of a challenge, and I think that's what turns people off," said Pinak Shah, M.D., director of the fellowship program at the cath lab at Brigham and Women's Hospital in Boston, who now does between 60 and 70% of his catheterizations transradially.
Differences in technology might also account for the preponderance of femoral access in the U.S., according to Mark Turco, M.D., director of the Center for Cardiac & Vascular Research at Washington Adventist Hospital in Takoma Park, Md.
The use of vascular closure devices, which are designed to reduce bleeding associated with femoral access, is much more common in the U.S. than in other countries, he said.
Dr. Turco said that as the technology of closure devices improves, allowing hemostasis to be achieved in two or three hours, there's less of an advantage to transradial procedures.
Limitations of Transradial Access
Beyond training issues, there are some limitations to the procedure itself, as most interventionalists agree.
Physicians using the radial approach have slightly more radiation exposure, according to Dr. Rao. That's probably because the more challenging manipulation of the catheter requires the physician to step in front of the fluoroscope more often.
In addition, Dr. Rao said, arterial spasm can occur with the transradial approach, although a cocktail of nitroglycerin, a calcium channel blocker, and heparin has made this less of an issue.
Catheters are sleeker now too, he added, further reducing the risk of spasm.
Hand ischemia, which could potentially result in tissue loss or amputation, is also a risk, according to Dr. Turco.
But the main limitation of the transradial approach is the size of the equipment that must be used.
Most patients do not have a radial artery large enough to accommodate a 7 French catheter, but the femoral artery can usually take 8 French catheters and larger, according to Christopher White, M.D., director of the Ochsner Heart and Vascular Institute in New Orleans and editor-in-chief of Catheterization & Cardiovascular Interventions, the journal of the Society for Cardiovascular Angiography and Interventions.
"I think American interventionalists tend to want to have all of their options available to them," he said. "Even if they start with a 6 French, they want to be able to size up to an 8 if they need to."
But even with the equipment constraint, Dr. Coppola said, "you probably can do over 90% of your procedures transradially."
What the Future Holds
Drs. Rao and White both cited a lack of a concerted effort on the part of the device industry as part of the reason transradial access has not approached even a fraction of that percentage.
The reality of clinical practice, according to Dr. Rao, is that most interventionalists find out about new devices and techniques from the companies working on the front lines.
According to Dr. White, The uptake of transradial access "could be accelerated if equipment manufacturers would support it a little bit more."
But Gary Clifton, marketing manager for Terumo Interventional Systems' coronary product line, says a "perfect storm" has developed that would foster the use of transradial access.
He said because of a desire on the part of government to reduce healthcare costs, an increased focus on bleeding complications because of the development of more potent anticoagulants, and the presence of a company willing to push for the use of transradial access, more movement would happen in the next few years.
Terumo markets a line of guide wires, catheters, introducer sheaths, guiding sheaths, and other products designed specifically for the transradial approach.
The company has developed simulators that allow interventionalists to practice the transradial approach before stepping into the cath lab.
The company also sponsors a one- or two-day training program in which interventionalists who have been using the transradial approach host physicians looking to learn it.
This effort, Clifton said, is in anticipation of a push from government agencies, such as the Centers for Medicare & Medicaid Services (CMS), to cut costs through an increased use of outpatient procedures.
Dr. Turco agrees.
"We may actually see increasing percentages of transradial access here in the U.S. with more of a governmental and insurer push for same-day discharges of interventional patients," he said.
Also agreeing was Paul Zimnik, D.O., executive director of the Patient Medical Association (PAMEAS), a Washington-based advocacy group working to increase the use of transradial access.
"You really cannot be talking about an outpatient interventional program without a radial approach," he said. "I know CMS knows this."
PAMEAS has a goal of seeing 20% of all catheterizations done transradially in the next few years.
To help meet this target, the group organizes dinner programs discussing transradial access and works with large cath labs to train the physicians and staff in the procedure.
But Dr. Zimnik acknowledges that much more research needs to be devoted to transradial access.
To that end, PAMEAS is sponsoring a multicenter, randomized controlled trial comparing transradial and transfemoral access. Dr. Zimnik said he hopes to have initial results from the study to present at next year's meetings of the American College of Cardiology and the American Heart Association.
Dr. Rao agreed that there is still a lot unknown about transradial access.
"I think there's a dearth of information on what the complications really are," he said. "And so that suggests that we need to get away from this concept that the radial approach is manna from heaven and we really need to study it more."
While the data roll in, there does appear to be some movement toward greater utilization.
Dr. Rao said that when he speaks with other interventionalists who have not adopted the transradial approach, "the response I almost always get from these guys is, 'Yeah, I probably should do more.' "
He added, "I think everyone acknowledges that the radial approach is safer and just as effective as the femoral."
| Dr. Turco reported serving as a consultant for AccessClosure, which manufactures the Mynx arterial closure device.
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