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Tools of the Trade - Catheters & Cables


     Before the first case occurs, you will need to order your catheters, cables, introducers and a few odds and ends. Many people have asked what you need when you are starting out with a new program. What you use will be dependent upon the type of study that is performed.. Below is an equipment list that may be helpful for newer labs.

Diagnostic Studies

Introducers: When you are starting with simple studies, standard introducers will work fine. We will often use 5 and 6 french sheaths for our EP procedures. The number of introducers you will need will depend on the number of catheters that will be used during each case. There are some specialty introducers that are helpful also. Our lab has recently started using duostat sheaths from St. Jude Medical. These introducers come in 10F and 12F. Each allows the introduction of multiple catheters using only one venous stick. In our case, we place a 5F josephson to the RA and a 5F CRD2 to the HIS for the initial portion of our procedure. After atrial testing has been completed, the josephson catheter is repositioned to the right ventricle.

Catheters: The majority of EP studies can be started using three catheters. When a supraventricular tachycardia is induced, a fourth catheter will often be added to help identify the exact type of SVT that is occurring.

1) Quadrapolar fixed curve catheter to right atrium.
2) Quadrapolar fixed curve catheter to His bundle region.
3) Quadropolar fixed curve catheter to right ventricle. This catheter is often repositioned between the RV apex and the right ventricular outflow track. - Note that it is possible to perform a basic EP study using two catheters as mentioned above. This will help keep costs down.
4) Decapolar fixed or stearable catheter to the coronary sinus if needed to classify SVT.

Each catheter will require a cable to connect it to the junction box. When you order your catheters, order the corresponding cables with them. The cables are often resterilized for repeated use as they do not enter the patient's body.

You will also a larger 20 pole to evaluate atrial flutter or atrial tachycardia. There are several varieties of these catheters available including the Duodeca from St. Jude Medical, the Stabl Mapper from Medtronics and the Halo and Crista catheters from Cordis Webster. For difficult atrial tach cases, the basket catheters from EPT are also helpful, those these have largely been replaced by the advanced mapping catheters. Basket catheters use either multiple cables or special hookup. Be sure to contact your industry Rep for instructions on how to use these catheters.

How many catheters you should have on hand depends upon how many procedures you plan on doing each day. We usually order equipment every afternoon using 2-3 day shipments. It is rare that we do more than three cases per day so we adjust our catheter inventory to make sure we have enough stock on hand. Our primary physician uses a two catheter approach for most of his cases, so we keep 12 quadrapolar josephson catheters for RA and RV use, 12 quadrapolar CRD2 catheters for His recordings and 9 decapolar CS catheters. For atrial flutter or atrial tach cases, we keep three 20 pole catheters available. This basic inventory level allows us flexibility to handle shipping delays and periods of time with unexpected heavy case loads.

Intervention Cases (Ablations)

RF Generator:   In order to perform ablations, you will need an RF generator. There are a variety of these available, each with different functions. Our lab has used the Atakr2 by Medtronics, the Stockert Generator from Cordis Webster and the RF generator from EPT. We eventually settled on the Atakr2 because we use a fair number of Medtronic ablation catheters. Many of the companies will allow you to have an RF generator at no cost with an agreement to use a specific number of their ablation catheters. When you decide on a specific ablation unit, be sure to order the ablation cables and grounding patches required for that particular unit.

Ablation Catheters:   It has been my experience that each physician will have one or two catheters that he prefers for ablations. While you may convince your doc to try some different catheters, don't be suprised when they ask for their old favorite. Always keep plenty in stock. That being said, there are a variety of catheters to choose from. Each company provides numerous different catheters. While I am not going to list them all here, I will mention some features to be aware of.

  • Tip size:  Most ablation catheters have 4mm tips. The tip is the point of the catheter that makes contact with the myocardium during the ablation process. From time to time, you will encounter a difficult case where normal procedures just don't seem to work. It is advisable to have a few catheters with 5mm tips for these cases. The larger tips can help create deeper lesions and may be beneficial in cases where the arrhythmia may originate or pass through deeper tissue than normal.
  • Catheter/Curve Length: Some catheters come in short and long lengths. Many of the companies provide different curve lengths to reach specific areas in different size hearts. This can be very important when working with smaller patients. Check with your company reps to see what different types of catheters they provide.

Specialty Sheaths:  Another useful tool for ablations are the specialty sheaths. These are helpful when trying to position ablation catheters to specific regions within the heart. Both St. Jude Medical and EPT have a variety of specialty sheaths that are designed to help position your catheter at the appropriate focal point of ablation.

*** Here's a tip: Try using a St. Jude SL3 sheath for flutter ablations!! The SL3 is designed for left atrial work, but Dr. Thampi John of Fresno California uses it with great success for right atrial isthmus ablations for typical atrial flutter. ***

Transseptal Equipment:  When an arrhythmia originates in the left atrium, it will be necessary to cross the septal wall in order to achieve a successfull ablation. To do this, there is some specific equipment that is required.

Brockenbraugh Needles - You will want to have the BRK and the BRK1 needles available.
Transseptal Sheaths - Again, there are a wide variety of sheaths available from the different companies.
Ice Catheter / Intracardiac Echo - One useful tool in crossing the fossa ovale is the intracardiac ultrasound. This system is available from Boston Scientific and is a great tool for those starting out in transseptal procedures.

Connecting the Cables

          The way that the catheters are designed, one end has the cable connection. The other end is placed inside the patient's heart. This is called the distal end of the catheter. On the distal end of the catheter are the electrodes. For the basic quadrapolar catheter, there are four electrodes. In order to make things easier to identify, the great makers of the EP catheters came forth and decreed that the electrode closest to the distal tip will be #1. The second one from the end will be number two and so on. To transmit the signals from these electrodes, each cable was designed with a single wire connection that would correspond to a specific electrode. These wires are located at the proximal end of the cable and are labeled Distal (for #1), 2 for the second electrode, 3 for the third and 4 for the most proximal one. This pattern of D,2,3,4 is what allows you to program how the signals collected from the catheter electrodes will be displayed on the monitor screens.

          OK, the signal has now come down the catheter and into the cable. We still need to make it show up on the screen. The next thing we need is some way to hook the wires from the cable into the EP monitoring system. This is achieved using a junction box. The junction box for most systems looks like a small rectangular block with lots of little holes in it. The shapes may vary a little, but the function is the same. The junction box allows us to use any electrode in the creation of an intracardiac signal. Two electrodes are used to create one signal. One electrode is assigned to be the negative pole and another is programmed as the positive pole. Once this is done, the intracardiac signal can be interpreted in much the same way as a surface electrocardiogram. A signal moving towards the positive electrode appears as an upward deflection and a signal moving away from an electrode appears as a negative deflection. To help keep things standardized, the most distal of the two electrodes is selected as the negative pole. With this basic information, we can now hook up our cables and program the monitoring system to display the signals we need.

          So let us hook up our right atrial quadrapolar catheter and program the system to display the signals we want to see. As mentioned before, the wires at the proximal end of the cable, marked distal, 2, 3 and 4, correspond to the electrodes at the distal end of the catheter. Hook these into four channels on your junction box. Because we are working with the right atrium, and this is where electrical signals in the heart originate, let's use the first four spaces on the junction box. The distal wire of the cable is hooked into the space or port marked one, number two goes to port number two and so on. We then go to the setup page of our EP system. The setup page is what allows you to program your system to display specific signals from either surface or intracardiac electrograms. When the setup page is opened, select a blank channel to program. Name the channel RA proximal. You may not be able to get all the lettering in the space provided. This is why you see names like "Rap" or RA Prox" on some intracardiac recordings. Once the channel is named, you will need to select which space on the junction box is your negative channel and which is your positive channel. Select 3 as negative and 4 as positive. You may want to start with one and two, but we will be using those connections for the RA distal channel. Once the Rap channel has been programmed, select the next available channel for RAd. Use space 1 as negative and 2 as positive. This gives us our second channel. The proximal RA channel was programmed first because the signals will usually display in the order that they are programmed. It makes it easier, if you are starting from scratch, to do it this way. Most systems will allow you to change the order that channels are displayed without having to completely reprogram them.

          So now you have a proximal right atrial channel displayed over a distal right atrial channel. This is the way most systems are configured to display a quadrapolar catheter. It is not required that you show the proximal channel above the distal channel of each catheter. However, this is the setup most commonly used in EP labs, and it makes a lot more sense to do it this way when you get to the coronary sinus catheter. Once the right atrial catheter is connected and programmed, use the same method to program your HIS catheter. This time, plug the distal wire of the cable from the HIS catheter into port number 5 on the junction box. In a corresponding manner, plug wire number 2 into port 6, wire number 3 into port 7 and wire number 4 into port 8. It really doesn't matter which ports on the junction box you use as long as you plug the distal wire first and follow with the remaining wires into sequential ports on the box. On the setup page, program you HISp channel with 7 as the negative pole and 8 as the positive pole. Your HISd would have 5 as the negative and 6 as the positive poles. Using this technique, you could then set up another quadrapolar catheter for the right ventricular apex. The cables for this catheter would be plugged into ports 9-12. The RVAp channel would be set up with 11 as the negative pole and 12 as the positive pole. For the RVAd channel, 9 would be negative and 10 would be positive. Once you have become completely familiar with hooking up catheters in this manner, you will be able to set up any catheter configuration you want. Trust me when I say, you will need to know this so well it almost becomes instinct. Sooner or later you will reach the point where the physician wants to review your catheter connections because he is seeing signals that don't make sense. Be ready for this to happen. You will look real good when you can explain how everything is hooked up without hesitation. It will also build the physician's confidence in you when he sees that you know exactly what you are doing.

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