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EP Procedures - Setting Up

Pre Procedure / Patient Prep

Prior to the patients arrival in the lab, the room and the equipment must be set up. For dedicated labs, this is a simple and straight forward procedure. Even for multipurpose labs, this is a fairly straight forward task. Here are a few tips on how to approach the set up process so that the procedure will run smoothly.

Power Connections

One of the more pervasive problems that may be found in the lab is noise on the various systems that document electrograms. A simple way to help minimize this is to use common plugs for specific pieces of equipment. When different pieces of equipment are all plugged into a common electrical outlet this provides them with a common ground. This means they are all grounded in the same way and the chance for electrical noise is minimized. Note that multiplug adapters of the type that you can buy at Walmart or Home Depot are not certified for use in the medical environment. If you are short on plugs, contact your Biomedical Engineering Department and request medical grade multiplugs. They can provide you with units of four plugs that are grounded at a level that is appropriate for use in the lab. Doing this will remove the need to hide the other power strips when JACHO is in town. It also provides a safer environment for the patient and yourself.

When dealing with a limited number of plugs, consider the following pieces of equipment as having the highest priority for a common set of outlets; the amplifier for the recording system, the amplifier for the mapping system and the RF generator and pump for irrigated tip catheters. All these pieces of equipment are connected, directly or indirectly to the ablation catheter. As such, they share a common point of electrical interaction. Having all these items using a common ground may have a profound impact on the clarity of the electrograms documented.

Skin Prep

Prepping the skin for placement of the wide variety of electrodes that are used in an EP procedure has become a fine art in the EP lab. Knowing the correct approach may differentiate the level of difficulty that various labs experience. As an instructor, I have often had the opportunity to interact with staff from various labs and can testify to the difference a good skin prep has on a procedure. The following it the technique I teach to my classes.

Step I: Skin abrasion - Gently rub the surface of the skin with a wet four by four. The woven structure of the 4x4 removes dead skin cells that are not visible to the naked eye. This allows for good contact by the adhesive for the patches.

Step II: Clean the skin - A good soap or rubbing alcohol should be used to elimiate oils from the skin. This allows optimal contact with the gel from each type of electrode with the skin. Note that alcohol is a skin irritant and may cause mild burns if not allowed to completely evaporate before placement of the patches.

Following these two simple steps will provide the lab with excellent signal quality.

Patch Placement

It is important to understand that the various different patches that are connected to different systems may interact if placed in close proximity. Patches should never overlap. This is almost a guarented formula for interference between the systems whose patches are in contact. Some patches should not even be placed in close proximity to each other. A system reference patch for any system should never be in close proximity to the RF dispersive electrode patches. If this occurs for an impedanc based navigation system, navigation errors are probable. At least 3 inches should seperate the system reference patches from any RF dispersive electrodes.

RF dispersive electrodes act as the return current for radio frequency energy used for the ablation process. Appropriate placement of these patches may have a significant impact on the success of an ablation procedure when RF energy is used. If the target site is completely anterior, a posterior placement of the RF dispersive electrode may shunt the energy away from the tissue to such a degree as to result in ineffective ablation. If the area of interest is completely anterior, especially in the ventricle, anterior placement of the RF dispersive electrode should be considered.

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