Transradial Access at the University of Miami
- Volume 17 - Issue 9 - September 2009
- Posted on: 9/14/09
- 0 Comments
- 10872 reads
Dr. Mauricio Cohen has been performing transradial access procedures for approximately 5 years. After joining the University of Miami Hospital cath lab in January of 2009 as director, he instituted a transradial program.
Dr. Cohen, where did you first learn transradial access?
I was exposed to these procedures during my training in Argentina back in the mid-1990s. In 1994-95, we did a randomized study looking at radial, brachial and femoral access, and it was during this study that I was exposed to transradial access. I learned the nuts and bolts of the transradial procedure, but did not incorporate it into my practice until ten years later.
What’s your sense of how transradial access is utilized in Argentina?
I believe it is used slightly more than in the U.S., but not quite as much as in high-use countries like France, Canada, Spain or Sweden.
How often do you use transradial access in your current practice at the University of Miami?
I use it in 80-90% of my cases. When I approach a patient, the first thing I do is check the radial pulse. My mindset is that every patient is a candidate for transradial catheterization, unless contraindicated. Therefore, every patient is a radial case by default.
What are some of the reasons not to use the transradial approach?
There are very few contraindications for transradial access. These include the presence of an occluded radial artery, usually secondary to a previous procedure; lack of radial pulse; hemodialysis with an arterio-venous (AV) fistula in the forearm, and an abnormal Allen’s test. It is worth mentioning that we perform the Allen’s test using pulse oxymetry and plestismography to test the patency of the palmar arch. With this technique, less than 2% of patients will have an abnormal test. If there is previous coronary artery bypass graft surgery with a left internal mammary artery (LIMA) graft, we can puncture the left radial artery. As a matter of fact, engaging the LIMA is fairly simple and safe with this approach. If a patient has an occluded right radial artery, we will use the left radial artery, and then if we are unsuccessful, we will use a femoral approach.
How often do you find that you are converting to femoral access after beginning with a radial approach?
I’d estimate that occurs in less than 5% of cases. A common reason is tortuous anatomy. A tortuous subclavian would preclude access of the catheters to the ascending aorta. However, there are very few cases in which I have to convert because we are now able to negotiate the significant tortuosity associated with radio-ulnar loops, spasm or other problems that may present. I do think my rate of femoral conversion is actually decreasing.
How do you solve the problem of tortuosity?
It is important to keep in mind some basic rules when you do radials. You never push. Every procedure must be done with finesse. When we find that the wire is not going where it should be going or feel unusual resistance, we take a limited angiogram that will allow us to uncover the problem — anomalous anatomy or severe spasm. If it’s severe spasm, then we will give more vasodilators such as verapamil and nitroglycerin, and sedate the patient more. If it is a true anatomic problem, then we can sometimes use smaller wires and different catheters, such as a hydrophilic-coated catheter, to navigate the tortuousity, and then exchange for a stiffer wire that will straighten the vessel. Sometimes, when we cannot negotiate the tortuosity, we will convert to transfemoral access, but this is a rare occurrence. It is important that within one’s learning curve, the inexperienced operator be aware of his/her own limitations and convert to femoral access before causing a vascular perforation in case of very tortuous anatomy.
In general, we use 3 mg of intra-arterial verapamil in every case right after inserting the sheath. We use a dedicated access kit with a hydrophilic-coated sheath. It goes into the vessel very smoothly and I think it is less traumatic, so that’s an additional factor to prevent spasm. Sometimes we need to use additional doses of sedatives to prevent the adrenergic release associated with anxiety. We see spasm in 5-10% of cases, but in the past six months, I haven’t seen spasm severe enough to make me switch the access site.
When patients have severe vasospasm and severe pain, it may be a sign that there is a vascular anomaly, such as a radio-ulnar loop. Sometimes the catheter may have gone through a communicating vessel between the ulnar loop and the brachial artery. This communicating vessel is usually very narrow and reacts to the catheter with severe spasm. In these cases, when the patient feels severe pain, a limited angiogram helps us understand the problem.
When you are presented with challenges during radial access, why go the extra step of trying to work through them? Why not simply convert to femoral access?
We put in additional effort because the patient already has arterial access and because we believe that transradial access adds significant safety to the procedure. If you think you can safely negotiate the tortuosity, and feel confident it can be done with the equipment you have, I don’t see a reason for not doing so.
Is there a problem with excess contrast with transradial access?
It depends. Many studies have shown that transradial access increases radiation exposure to the physician, as sometimes the cases are slightly longer. I believe that any additional radiation exposure is offset by the significant benefit it delivers in terms of patient outcomes. What we also need to keep in mind is that if you don’t commit to using transradial access on a regular basis, you will never become truly proficient at it. The more you do, the better you become. Using a one-catheter technique, I can complete a transradial case in as little as two to two-and-one-half minutes when working alone, as I don’t need to exchange catheters to selectively engage each coronary artery. When I am the operator, I believe the radiation is at the same level as when I utilize femoral access.
There is no question that a set of skills are needed to become proficient in transradial access. It takes about 100-200 cases to become experienced. A skilled operator with good hands can master the technique much faster. One of our fellows was first exposed to transradial access when he started to cath with me. By the end of his one-month rotation, he was independently performing a complete transradial case. I was not scrubbed in. This fellow has very good hands. He got access, engaged the right and the left coronary artery with the same catheter, and then finished with a ventriculogram. I was very pleased. So both skills and a positive attitude are necessary for the adoption of this technique.
Do you prep the femoral access site even when you are planning to do transradial access?
It depends on the situation. I always evaluate the patient before the procedure to determine if a groin prep is required. I recently treated a male patient who was fairly young. He had a very good radial pulse and the nurses asked me if I wanted the groin prepped. I said no, as I did not foresee any problems getting radial access. On the other hand, when I see a “little old lady” with a weak radial pulse or a patient that is clinically unstable (i.e., STEMI), I may request a groin prep as back up.
Some have said that women have a higher conversion rate (to femoral access), but they are also the ones who benefit most from transradial access.
You would think that women with their smaller body size and smaller radial arteries would have higher conversion rates, but I haven’t seen that in my experience. In fact, I’m not sure that this has been well-described in the literature. But you are right about the benefit, because female gender and older age are two major risk factors for bleeding. If you eliminate the vascular access site as the source of bleeds, then you eliminate 60-70% of the chance of bleeding. Registries have shown that 60-70% of the bleeds that occur after transfemoral percutaneous coronary interventions originate from the vascular access site.
Do you perform ST-elevation myocardial infarction (STEMI) cases with transradial access?
Transradial access is substantially beneficial in these cases. STEMI patients receive a large bolus of heparin in the emergency room and we use GP IIb/IIIa inhibitors in the cath lab. Therefore, they are at high risk of bleeding. At University of Miami, as well as in my previous position at University of North Carolina at Chapel Hill, I have been performing more than 50% of my STEMI cases transradially. Some of our STEMI patients are transported by air from the Florida Keys straight to our cath lab having received at least one bolus of thrombolytic therapy. Therefore, transradial access is very convenient and safe in these cases.
Have you noticed a decrease in your bleeding complications?
Anecdotally, I believe this is the case. I have not looked at enough of our data yet. There is no question that patient comfort is much better and patient length of stay is much shorter. Equally important, when I go home at the end of the day, I am very confident that patients are not going to bleed and I will not be called in the middle of the night because the patient is having a huge groin bleed or has developed a life-threatening retroperitoneal hematoma. This confidence gives me peace of mind.
How does the transradial approach affect scheduling in your cath lab?
Transradial patients have a significantly shorter recovery period. They can get up right away and do not need assistance to go to the bathroom. Obviously, there is a decrease in nurse workload, patients go home sooner and the flow improves substantially. Sometimes we have to bump patients scheduled in the morning because an acute case presented to the emergency room. We then have to do these elective patients by the end of the day. Transradial access in elective patients is greatly advantageous because these patients can generally still go home as a result of this access strategy. If we did these cases via femoral access, then we have to admit them overnight in order to watch their groin. Another situation is when a patient is admitted with chest pain and we have to rule out an MI. Even after three enzymes are negative, a physician may still feel that the patient should have a cath. We do the cath transradially, so that if the patient does not need an intervention, the patient can go home immediately following the cath. Transradial access generally allows the patient to leave on the same day, therefore avoiding a night’s stay.
The cath labs at University of Miami are used by a wide range of physicians. Have you seen any interest across the various disciplines regarding transradial access?
The beauty of this cath lab is that we all interact well. There’s a very friendly relationship among physicians of different specialties and subspecialties, including vascular surgery, vascular interventional radiology, interventional cardiology and electrophysiology. We also have an aortic valve program and some of the cases are done in a hybrid cath lab with the help of a surgeon, since these cases need transapical access. As yet, I have not been able to do cases with physicians of other specialties, but it is definitely in the works. Several vascular surgeons and interventional radiologists have expressed interest in the transradial approach. We also have a few “interventional nephrologists,” who are also very interested in the technique.