Index
Ep Defined | Getting Started | Working in the EP Lab
Right Atrium | Right Ventricle | Left Atrium | Left Ventricule | Cardiac Conduction | Cardiac Cell Properties | Action Potential | Sympathetic or Not | Med Page
Electrograms Defined | Recording Modes | Electrode Spacing | Filters | EGM Interpretation | Arrhythmia Analysis
The Physical Lab | Tools of the Trade
Setting Up | Catheter Placement | Baseline Measurement | SNRT | Conduction Study | Arrhythmia Induction | Pacing Protocols | Ablation | Tilt Table | Secrets to Success
Bradycardia | Atrial Tach | Atrial Flutter | Atrial Fibrillation | AVNRT | AVRT | Ventricular Tachycardia
Surface ECG's | Intracardiac Questions | Med Challenge | Advanced

Working in the EP Lab - Patient Care

Taking Care of the Patient

          In many of the articles presented in this venue, there are comparisons between the cardiac cath lab and the EP lab. Understanding these differences helps anyone who is making the transition from one area to the next as well as helping anyone who acts in a supervisory role over these areas. For the Registered Nurse, and to a certain extent, the CVT, the patient care aspects of EP procedures bears strong similarities to those performed in the cardiac cath lab. There are, however, some important differences that caregivers need to be aware of during electrophysiology procedures. The following pages contain information that any caregiver working in EP should find useful.

Pre Procedure / Patient Prep

          When I first started working in EP, it was not uncommon for the patient to arrive in the lab with only a vague idea of what exactly was going to happen. Those of us who worked in situations like this became adept at providing answers to the many questions the patients would have. In most of today’s EP programs, the information provided for the patient is much more extensive and the caregiver rarely finds themselves in the position of needing to answer a multitude of questions before the procedure. For those who are not fortunate enough to find yourself working in a program with good patient education, I have compiled some information on questions that many patients asked me or those that I have worked with. These can be accessed by selecting the Patient Questions link at the left side of this page.

          Another section worth reviewing is the EP Procedures page that deals with the pre-procedure setup. This section contains important information that can improve patient safety and increase the chances of having a successful ablation outcome. That section can be accessed by clicking EP Procedures / Setting Up.

          From the time that the patient arrives in the room to the time they leave, their well being is in the hands of the circulating nurse. While everyone contributes to the care of the patient, it is the job of the Registered Nurse to watch over the patient and alert the physician of any indications that something isn’t right. The best programs I have witnessed have nurses who are informed and educated about cardiac electrophysiology procedures and the specifics of patient care involved with these procedures. While virtually every nurse I have met would take the time to learn about the specifics of any procedure they worked on, the lack of educational materials on cardiac electrophysiology created a significant obstacle for anyone who was seeking to learn about EP outside the lab. This restricted electrophysiology education for the nurses to the time immediately before, during or after the procedure. This, of course, was the one time when they could not afford to divert much attention from their primary duties. For this reason, many nurses found it extremely difficult to gain a significant interest in EP, and it is for the caregivers who watch over the patient, that this section of the web page is dedicated to.

The "Down and Out" of Sedation

          At first glance, sedating a patient for an EP procedure appears to be no different that it would be for a cardiac catheterization. The goal is to keep the patient comfortable and relatively immobile. While this is, for the most part, a fairly straight forward event for most cardiac cath patients, diagnostic electrophysiology procedures present a whole new challenge to the person in charge of keep the patient sedated. I am not referring to the tough cases where it seems like nothing you do will keep the patient from moving, though that does happen from time to time. I am referring to the fact that many of the medications utilized for sedation have an anti-arrhythmic affect that is not desirable during EP procedures.

          One of the most frustrating events in the EP Lab is to have a patient on the table for lengthy periods of time without being able to induce the arrhythmia. Induction is usually accomplished by using different pacing maneuvers, though medications may also be used. Anyone who has worked in the lab for awhile knows the pain of trying over and over again to trigger an arrhythmic event. It is especially difficult to bear when the presence of an arrhythmia has already been documented at some other point in time. This amounts to the short straw for the physician, the lab staff and most important, for the patient. Everyone wants success in their efforts to eliminate the abnormal rhythm that is the cause of the patient’s trip to the lab.

          Due to the antiarrhythmic affects of many of the sedatives available today, there are times when little or no sedation will be used. This usually happens in patients with focal tachycardias that have been “no shows” in previous procedures. I have even seen times when benedryl has been used as a local anesthetic due to lidocaine’s antiarrhythmic properties. Minimal sedation can make it quite a challenge to keep the patient comfortable. The fluoroscopy table was designed for function, not for comfort. Patients with even mild back problems can experience severe discomfort after being on the table for more than a few minutes. There are times when the best you can do is provide verbal support to get the patient through a difficult case.

Need to Know...

          Being more involved with the procedures performed in the EP Lab will not only improve the odds that you will enjoy your time in the lab, it also adds to the safety provided the patient during the case. This is not to suggest that nurses do not get involved with the procedures they assist with in the lab. It is simply an acknowledgement that EP is a difficult field to grasp when your job keeps you focused on one small aspect of what is happening in the room. EP may seem, at first, to be a hideously boring procedure. Yet when the time is taken to learn about what is occurring during these procedures, the time seems to go a little faster. Who knows, you may even find you like it!! With that in mind, here is a brief overview of what happens during an EP procedure with some information on how what is happening may have an impact on you, the nurse. We have already addressed the pre-procedure and patient prep aspects, so we will move forward from there.

Sheath and Catheter Placement

          An EP procedure may require from two to six introducers depending upon the type of study being performed. For the circulating nurse, there are two things to be aware of. The first is discomfort that the patient may have at the insertion site. Even with lidocaine, there may be a bit of discomfort during sheath placement. The second and more important consideration is that of vagus nerve stimulation. It is not that uncommon for a patient to become vagal during this portion of the procedure. Significant drops in blood pressure and/or heart rate may occur without warning. This is usually transient, but may require medications to deal with the decrease BP or heart rate.

Baseline Measurements

          This will be a short and quiet period of time during the procedure when the tech will be measuring some of the basic intervals. Sit back and relax.

SNRT (Pronounced "Snert")

          The abbreviation SNRT stands for Sinus Node Recovery Time. This procedure involves suppressing the sinus node by pacing at a rate that is faster than the patient’s intrinsic rhythm. Pacing is maintained for 30 seconds up to a minute and then is turned off. The interval between the last paced beat and the first sinus beat is measured to determine if the sinus node is responding normally. In the vast majority of cases, evaluating the sinus node recovery time will not produce an anxiety moment. Even if the result is abnormal, it is rare to see a pause of more than 2 to 3 seconds. In extreme cases however, I have witnessed sinus node recovery times in excess of 10 seconds. This will cause your heart rate to jump up, especially if you were unaware of the possibility that this could occur.

AV Node Evaluation

          The AV node in most patients acts as the primary conduit of electrical activity between the atria and the ventricles. It also acts as a regulator to control how fast signals pass from the top of the heart to the main pumping chambers in the lower half of the cardiac structure. Because of the critical role it plays, the AV node is of significant interest to the electrophysiologist. Conduction problems can result in bradycardia due to heart block, and involvement with accessory bypass tracts, both inside and beyond the AV node itself can create conditions ideal for reentry tachycardias. Due to the potential involvement with both slow and fast rhythms, it is essential to establish how the AV node functions in almost all patients.

          Information on the function of the AV node can be obtained through either incremental pacing or programmed stimulation. Conduction delay or block may present itself, though this will usually occur for one or two beats at the most. While this may indicate the need for a permanent pacemaker, it is rarely cause for immediate alarm. More likely to require attention is the onset of tachycardia. Any pacing maneuver can trigger an abnormal rhythm and this may occur during the process of evaluating the AV node. The best way to respond to different arrhythmias is listed below.

Arrhythmia Induction

          As mentioned before, it is a good possibility that some of the pacing maneuvers utilized in the EP lab may induce an abnormal rhythm. This is, in fact, one of the primary functions of a diagnostic EP study. When this does happen, it is usually not cause for alarm. Many patients experience prolonged episodes of tachycardia without adverse affects. There are however, some abnormal rhythms that require immediate attention. Knowing what to do with any type of rhythm that occurs in the EP lab is the calling of an excellent EP nurse. Here are some guidelines that will help you to determine what type of response is appropriate with different types of rhythms.

SVT

          Supraventricular tachycardia is what you will encounter most often in the lab. Whenever any arrhythmia occurs, the first thing that needs to be done in most cases is to assess the patient. Is the patient symptomatic? By symptomatic, I am not referring to those cases where the patient is aware of the change in heart rate. In this instance, the term symptomatic is used to refer to patients who experience a significant drop in blood pressure with the onset of arrhythmia. So if the patient is aware of the change in rhythm, but appears to be tolerating it, the next thing to do is try to verify if what, if anything, the patient is feeling corresponds to any symptoms that may have lead them to seek out a physician in the first place.

          Ask the patient if what they are feeling now is similar to what they may have experienced in the past. If not, is it similar? Can they describe what they are feeling at the moment? These questions all provide insight to the nature of the patient’s rhythm abnormality, especially in cases where there was no documented arrhythmia prior to the procedure.

          Symptomatic SVT occurs much more infrequent than asymptomatic versions. The primary reason for the hemodynamic compromise is the rapid rates that occur with some arrhythmias. When you are at the start of a study and are gathering information on the patient’s history, there are certain terms or diagnosis’ that you should keep an eye out for. Any mention of syncope or near syncope should immediately cause the red flag to go up. If loss of consciousness is occurring in association with the arrhythmia, you are almost certainly dealing with a very fast rhythm. Note that “fast” may not refer to the physical beats per minute, but may also fall into the functionally fast category. Patients with severe valvular stenosis will not respond well to rates that most patients would easily tolerate. Keep this in mind when dealing with this patient group.

          Of all the supraventricular arrhythmias, WPW can produce the fastest response. When patients with Wolfe-Parkinson-White syndrome go into a tachycardia, the heart rate is regulated only by how fast the tissue can conduct electrical activity. Most accessory pathways do not display properties of decremental conduction like the AV node does. In simple terms, faster rates do not require longer recovery times before the next signal is allowed to conduct. WPW patients with pathways that conduct both antegrade and retrograde may be more susceptible to atrial fibrillation. If this occurs, the ventricles will be receiving every conduction wave front that passes through the accessory pathway from the fibrillating atrium. The danger here is obvious and this occurrence needs to be treated with the most aggressive appropriate response. It is not uncommon to have to defibrillate these patients.

          Another rhythm that should alert you to possible difficulties ahead is atrial flutter, especially in patients who are younger and otherwise healthy. When flutter develops in a patient with a good strong AV node, the possibility of 1:1 conduction needs to be considered. While this is not a common event, I have witnessed this event in the lab on a few occasions. One event was an 11 year old male who had a history of Fontan surgery for correction of congenital defects. This child was in excellent condition given his history and was even active in some outdoor activities. Unfortunately, these periods of activity usually resulted in the onset of atrial flutter, usually at a pretty fast rate. During the EP study, he experienced an episode of 1:1 conduction with a ventricular rate of 322bpm. His blood pressure dropped to 40 and aggressive measures had to be taken to stabilize him and get his rate under control. As I stated previously, this does not happen very often, but you do need to be aware that events like this are possible.

VT

          It is always fun to watch the response of a new nurse in the lab to an episode of ventricular tachycardia. So many times when VT occurs, the RN responds as they have taught to in the Cath Lab, Critical Care or Cardiac Telemetry Ward. In those environments, VT is almost always an emergent situation and is handled as such. What many of those who are new to the EP lab don’t realize is that in a patient with VT, we are trying to stimulate V-Tach to occur. Yes, we want it to happen as this is often the only way to confirm an accurate diagnosis of the mechanism that is the cause of the patient’s rhythm. Another fact that new comers to EP are often unaware of is that most patients with VT, especially those with ischemic VT, have reduced cardiac function to begin with and have compensated to be able to tolerate the lower cardiac output they experience on a normal day to day basis. In short, many of these patients tolerate VT very well.

          When VT does occur during an EP study, there are two very important decisions that must quickly be made. The first thing that must be determined is whether or not the tachycardia is monomorphic or polymorphic. This determination can be of critical importance for the following reason. If the VT is monomorphic, the Defib needs to be set in Sync mode. If it is polymorphic, the Defib unit should not have the Sync function activated. More than once, I have witnessed delays in delivery of defibrillation because Sync mode is selected and the patient is in a rapid polymorphic VT. To make matters worse, switching the Sync function on will dump the charge on most machines require several more precious seconds to recharge the defibrillator after adjusting to the correct mode.

          It is also possible to deliver an inappropriate shock when the defib unit is being operated in synchronized mode. Some polymorphic VT’s are often self terminating. You don’t want to be the one holding down the therapy delivery button when the patient converts to sinus and receives a shock on the first QRS the defibrillator can synchronize to. Delivering a shock in unsynchronized mode to a monomorphic VT is no better and may precipitate ventricular fibrillation. For this reason, most EP labs will have two defib units in the room during VT studies. One will be set to synch and the other will be set to non-synchronized mode. This can save precious seconds at the right time. It is the opinion of the author that conducting a VT study with only one defibrillator could be a medical legal issue given that for most labs, two defibs is standard procedure for VT cases.

          The second thing you must determine when VT occurs is how the patient is tolerating it. While this may seem to be the most important factor to determine first, if you don’t have the capacity to deliver the correct therapy when needed as mentioned above, then whether or not the patient tolerates it becomes a secondary concern. Assuming that the defibrillators are set up correctly, then establishing how the patient tolerates VT becomes the primary concern.

          When you are reviewing patient history at the start of a case, you can get an idea of what to expect based upon any available information in the patient’s history. The primary types of VT that you will see in the lab are ischemic and outflow track PVC’s. Premature ventricular contractions rarely manifest in prolonged runs of tachycardia though this can occur. Usually, you will be dealing with mapping single beats, most often from the right ventricular outflow track.

          Ischemic VT patients may have several different types of VT with a wide range of rates and morphologies. Sustained runs will usually be monomorphic at a relatively controlled rate. Ablation is most often attempted to control these slower, more persistent tachycardias, though with advanced mapping technology such as the EnSite Array, rapid unstable tachycardias can be mapped very quickly allowing the physician to target rhythms that previously would be left untouched. During the process of mapping ischemic VT’s, it is possible to see multiple different tachycardia circuits that may, or may not be associated with the clinical arrhythmia. Often, the choice will be made to target the primary arrhythmia only.

          Bundle Branch Reentry is a monomorphic VT that can be very rapid. Keep in mind the sync function and assess the patient.

          Arrhythmogenic Right Ventricular Dysplagia (ARVD), behaves similar to ischemic VT, though multiple circuits are less common. This is usually monomorphic and not exceedingly fast, but is often tolerated more poorly by the patient than ischemic VT is. The reason for this is that ARVD patients usually have not experienced the prolonged time with less than ideal cardiac function the way many ischemic VT patients have.

          In those rare cases when the target arrhythmia is a rapid polymorphic VT, you will need to be extra alert. Go into the procedure expecting a difficult case and be ready with every contingency. Most of the time, complex VT cases actually go pretty smoothly. When they don’t, having the prepared mindset becomes a big asset.

Ablation

          Once the diagnostic portion of the EP study has been completed, the decision may be made to move on to provide ablation therapy. When this happens, you may be able to provide the patient with some much needed relief. Previously, I had discussed the antiarrhythmic properties of many of the sedatives used during EP procedures and how this could make for a difficult case. Once the arrhythmia has been identified, the physician may allow the patient to be sedated for the ablative part of the procedure.

          Ablation, in and of itself, should not cause discomfort to the patient as there are no nerves in the heart to trigger a pain response. One of the rare locations where discomfort during ablation may occur is low in the right atrial isthmus during ablations for isthmus dependant atrial flutter. Based upon my own experience in the lab, an estimated 5-10% of flutter ablations may produce discomfort for the patient.

Transseptal Sticks, Anticoagulation and Perforations

          One of the more complex aspects of cardiac electrophysiology is the crossing of the atrial septum to perform left atrial procedures. An experienced physician can perform a transseptal puncture with little difficulty and in many labs, this procedure is common. With the widespread acceptance of ablation as a therapy for atrial fibrillation, more and more facilities are adding transseptal procedures to their practice. For this reason, it is important to understand the risks associated with the transseptal approach.

          The most significant potential complication lies in performing the TS puncture too high in the chamber. If this occurs, the needle may be advanced into the aortic root. Pressure waveforms from the tip of the transseptal needle are often monitored to provide immediate feedback during the procedure. If an aortic waveform is noted, the needle is immediately withdrawn. As long as nothing more than the tip of the transseptal needle entered the aorta, the potential for serious results remains low. If, however, the sheath is advanced into the aortic root, the situation becomes much more difficult to deal with. Surgical intervention may be required. Fortunately, there are a number of different safety measures that can be taken to minimize the potential of this happening.

          The greatest risk with transseptal procedures may be the need to administer heparin. This factor combines with the risk of perforation to produce one of the most dangerous potential complications that can occur in the EP lab, cardiac tamponade. Cardiac tamponade occurs when a perforation causes bleeding into the pericardium. Due to the lack of nerve tissue in the myocardium, perforations can occur without the patient being aware that anything has happened. When the patient has heparin on board, bleeding can be difficult to control and the pericardium will quickly fill with blood. As this happens, the heart is constricted and has difficulty in pumping blood. The excess fluid in the pericardial space must be removed immediately to avoid a catastrophic outcome.

          In many cases where perforation has occurred, the first indication is patient restlessness. When a patient begins to move around and shift position despite strong encouragement to be still, double check the blood pressure and O2 sats. This may be the first sign that a significant quantity of fecal material is about to hit the whirling blades of the fan. If the restlessness continues, it may be appropriate to inquire about calling for a STAT echo to rule out pericardial effusion. It is also a good idea to have a pericardial centisis tray close at hand.

          A perforation always signals the end of the procedure. It would be reckless, in my own opinion, to proceed once a perforation has occurred. The standard protocol is to tap the fluid, notify a cardiac surgeon (just in case), get a unit bed and provide supportive therapy. It is rare for a patient to require surgery to correct a perforation. It is also rare that mortality is associated with this event though deaths have been recorded. Fortunately, tools such as intracardiac echo have increased the safety of transseptal crossings by providing good visualization of the cardiac chambers before crossing the septum. It should also be noted that not all perforations are associated with crossing the septum. Any time heparin is used during an EP procedure, there is an increase in the risks associated with the procedure. A nurse who spots the signs early enough to avoid a significant negative outcome will have potentially fulfilled the greatest job any of us can hope for, to save a life.

Post Procedure

          At the end of the day when all is said and done, most nurses will find that the more they learn about electrophysiology and the more involved with the process they become, the more they will enjoy what they are doing. And if you try the EP lab, do not be disappointed if you find it is not for you. This is a field that people either love or hate. I have found very few people who have a mediocre opinion of EP. The great thing about nursing is that there are so many areas you can specialize in. If the EP lab is not for you, keep looking. Sooner or later you will find a place where the work becomes a pleasure. In closing, I would like to express an opinion that I have come to firmly believe, a good nurse in any job makes working in that area much easier to work in, a great one is worth their weight in gold. Great nurses will always have my respect and admiration.

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