Technique Workshop

As we perform complex coronary interventions in patients with ischemic coronary disease, we fundamentally have two or three different ways that we can access the coronary tree. The traditional and most commonly used approach is the transfemoral approach, where small catheters are placed into the right or left femoral artery and advanced through the aorta and then are positioned in the ascending aortic arch whereby the coronary arteries can be selectively engaged.

That technique has been used for many years. It’s relatively simple and it does allow the use of somewhat larger guiding catheters. However, it is associated with a not insignificant bleeding risk as well as the occurrence of structural complications to the femoral and to the iliac arteries.

As an alternative approach, one can go from one of the upper extremities, like the brachial approach, which is where the catheters are placed into the brachial arteries. This technique was initially performed by Mason Sones and was the standard way of performing cardiac catheterization in the early days of the procedure.

However, this generally requires a cut-down approach in its early phases or percutaneous approach and can potentially compromise the brachial artery, which is an important blood supply to the forearm. More recently, there has been a movement towards using the radial artery as the preferred conduit to engage the coronary arteries.

The radial artery is unique because it has a dual blood supply. It allows one to perform a catheterization procedure without compromise of the blood supply to the hand, provided that the ulnar artery has patent blood flow as demonstrated by a noninvasive test that we perform – called an Allen’s test – or with sonography.

The radial approach is preferred for many reasons. One is that it’s relatively simple to perform and the patient is ambulatory immediately after the procedure. Secondly, because there can be direct compression over the radial artery, there is a lower bleeding complication rate. And, thirdly, because in obese patients the radial artery is a relatively superficial artery and can be easily accessed.

Many practitioners are learning the radial artery technique, are understanding how valuable it is as an adjunct technique, and have learned that this technique may have substantial benefits in patients who may have complex anatomy, may be markedly obese or may have substantial peripheral vascular disease that will preclude the use of a conventional femoral approach.

Devices

The traditional size of the catheters used for the radial artery technique are either five French catheters for diagnostic purposes or six French catheters for traditional coronary intervention.

On occasion, a seven French catheter can be used if the forearm is large and in some men, an eight French catheter can be used, but typically we try to use the smaller French-size catheters in order to avoid any radial artery trauma.

The significant advancement in terms of devices has really been the introduction of the hydrophilic sheath. The hydrophilic sheath allows entry into the radial artery without traumatizing the vessel.

One of the challenges of the radial artery is the radial artery spasm that can sometimes cause pain and difficulty moving the sheath in and out. This is markedly reduced with the use of hydrophilic sheaths.

The second techniques that we’re gaining more familiarity with are specifically designed catheters for the use in radial arteries. Traditionally, we have used just standard right and left Judkins catheters or Amplatz catheters to engage the coronary arteries either diagnostically or for therapeutic procedures. But I think some specially designed catheters can be useful: a single-use catheter can be used for left ventriculography, for left coronary injections and for right coronary injections.

Once the procedure has been done, there is a variety of different compression devices that will allow a three- to four-hour compression on the artery while the artery heals itself.

Typically what happens with the coronary devices that go through the radial artery is they become smaller in profile and more deliverable. This allows us then, through a six French sheath, to do more complex coronary procedures including bifurcation lesions and some atherectomy procedures with smaller rotational atherectomy burrs.

Training

There are several components to physician training that goes with the radial artery technique. The first is an academic knowledge of the technique, knowledge of the coronary anatomy, knowledge of the physiology that occurs, and knowledge of the general guiding catheters and complex anatomy that occurs in the proximal portion of the arm vessels.

The second technique is learning how to cannulate the radial artery and then how to navigate through some complex proximal WORD NOT AUDIBLE disease. This is best performed using simulators and simulation training, particularly in the radial artery technique, and it is very useful for physicians to understand some of the initial mechanics of the procedure.

And the third thing, and obviously the most important piece, is actually performing the procedure in patients. The best way for physicians to get into this is to perform the radial artery technique on patients who undergo elective catheterizations who have good-sized vessels and good radial artery pulses. It’s very difficult for physicians who are not trained in the radial artery technique to take on the most difficult case, a patient with limited vascular access and peripheral artery disease.

Challenges

Well, I think the real challenge that we have in some patients and certainly we need better wires and more flexible wires and guiding catheters are some of the challenges for the great vessel tortuosity because sometimes there has to be a circuitous force that is taken as the catheters are passed up to the coronary ostium.

So certainly we’re learning with better techniques and better guiding catheters and better wires that a lot of these challenges can be overcome.

The future

The transradial approach has been used in less than 10 percent of procedures, at least in this country. Some centers are extremely dedicated, where 80 or 90 percent of the cases are done via the radial approach and the nurses and the recovery group are really set up to do those procedures.

So I think that the real challenge to the radial artery technique is not so much the fact that there hasn’t been a maturation of the technique, but that there hasn’t been an engagement of the community in performing these techniques. Over time, having a proficiency in the radial artery technique is a necessity for any interventional cardiologist.

You must have a certain level of proficiency in the technique, and that’s important for all interventionals. I might venture to guess that maybe half of the interventionals in the country don’t perform radial artery technique and haven’t done it before. Instead, they have used the brachial artery and that’s a limitation, I think.

Once it’s used more commonly, you can extend it into more complex lesion anatomy, such as patients with acute myocardial infarction. That is the next frontier because there’s less bleeding. The patient is more ambulatory.

Dr. Jeffrey Popma is Director of Interventional Cardiovascular Medicine at Caritas Christi St. Elizabeth’s Hospital in Boston, Massachusetts, part of a six-hospital network within the State of Massachusetts that’s aimed at providing high-quality community-based cardiovascular services.

Prior to his current role, Popma was on faculty at the Brigham and Women’s Hospital and associate professor of medicine at Harvard Medical School.