Ask the Clinical Instructor: A Q&A column for those new to the cath lab

This is a popular question and has been asked at nearly every review course in which I have participated. While the exact scope of what you need to know about the catheters referenced on the exam is too much information for this short article, we can certainly discuss some of the basic information concerning coronary angiographic catheters. First, don't worry about all the special names vendors give their catheters. Brand names are not on the exam. What you will see are the standard acceptable shapes and designs, which we will discuss later. Understanding the basic construction components of the catheter is important. Almost all angiographic catheters are manufactured in the same manner. They might have some subtle differences, but have the same basic components. Figure 1 shows a Teflon lining (PTFE). This makes a slippery coating so that wires and balloons and such can slide through without much friction. Figures 2-3 show a polyurethane or nylon material (different vendors use different materials) that has a wire braid integrated into it. This braid not only gives the catheter strength (such as the psi maximums), but also allows for the torque that the physician may require in order to get the catheter to go where it is needed. While waiting on a physician sometime, grab the tip of the catheter and then grab the other end (hub) and rotate it. You will see that it is almost a one-to-one rotation capability. Figure 4 is a hypothrombogenic material (again, this varies by manufacturer) that is intended to resist clotting WHEN WET. To keep things simple, we will talk next about commonly used catheter shapes. These are the catheters used to access the left coronary ostium (Judkins left, Amplatz left), the right coronary ostium (Judkins right, off-set right), and flood catheters (multi-purpose and pigtails). When Drs. Mason Sones and Melvin Judkins began performing percutaneous angiography, Dr. Sones developed brachial access catheters (still in use today, but not as frequently) and Judkins developed and perfected, femoral access catheters, which have taken on his name. JL4 is a standard left coronary ostium access catheter, with JL being an abbreviation for Judkins left. (We will talk about what the 4 means in a moment.) The JL4 is widely accepted as the catheter of choice for a large majority of catheterizations. Its curve allows for easy placement into the left coronary ostium. Dr. Kurt Amplatz designed the catheter that carries his name. While the AL versions of this catheter access the left coronary ostium, the AR version can also access the right coronary ostium. While its use is not standard, the Amplatz catheter is a common backup in difficult cannulation of the ostium. The most important thing to remember about the use of this catheter is that removal from the ostium requires a downward push and twist to prevent the tip of the catheter from diving deep into the ostium in which it is seated. Right coronary catheters generally offer fewer available choices. Due to the anatomy of the aorta and the location of the right coronary ostium, a Judkins Right (JR) or an off-set right (for example, 3DRC [Cordis Corporation, Miami, FL] and WRC [Boston Scientific, Natick, MA]) are used. When the visualization of a large area is desirable (ventriculography or aortography), a flood type of catheter can be used (pigtail, multi-purpose, etc.). A flood catheter is used because there are generally multiple holes for the contrast to exit the catheter during the use of a power injector. If a single-hole catheter is used during a large-volume, high-pressure injection, damage to the heart and/or vessels could occur, because of the high pressure jet that would come out of the end of the catheter. When the same injection is used in a pigtail catheter, there are multiple points of exit at the end of the catheter, preventing high-pressure jets, and allowing a flood of contrast in the area to be observed. You may have noticed that many of the Judkins type of catheters have numbers associated with them. These can range from 3.5 to 6. This number simply refers to the catheter's reach in centimeters. As a general rule, the larger the person and their aorta, the larger the catheter number. The various curves associated with catheters are another area covered by the exam. The curve nearest the tip of the catheter is the primary curve. This curve is sharp or gentle, depending upon the catheter chosen and its normally intended target. The secondary curve is the next curve, coming proximal from the tip. The secondary curve is generally placed against a structure (mostly the aorta) in order to help the catheter land and stay seated in its intended target. The tertiary curve, or the third proximal from the tip, also helps the catheter stay seated in its intended location. These curves make up the specialty applications for all catheters intended for a specific target. In patients with anomalous arteries, knowing the curves can help speed up the process in choosing one that will allow appropriate angiography. You will also quickly learn that while there are basic concepts to catheter usage, patients don't always present in basic ways, and ingenuity is often required. It is not uncommon to use an AL1 to access the right coronary artery, or a multi-purpose to complete an entire heart cath. If you know the many shapes and curves, you can often recommend unique alternatives to the physician in order to best complete the task at hand. While the topic of catheters can take up several pages to provide all the information that you, as a technologist, need to know, we have discussed some basic points that apply to almost any catheter, regardless of vendor or name. As a technologist in the cath lab, take it upon yourself to learn all you can about the catheters in use during the day. Catheter clinical representatives can also help you obtain the information you need in order to be a catheter expert. Submit your questions or comments to: Todd Ginapp at: tginapp (at) rcisreview. com

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