Ether– Resources for Anesthesia Research and Education

Stanford Electrophysiology Rotation

Electrophysiology Cases Guide(revised April 2021, Sunita Sastry).

Introduction:  

The MSD faculty are the anesthesiologists for Cath lab EP cases. For complicated patients, i.e. patients recently post cardiac surgery, complex cardiac problems, in CVICU, cardiac anesthesia may help manage the case. If you have concerns, please page the Cardiac Anesthesia scheduler for the day and discuss your concerns.

There are headsets worn by the cardiologists for ablations. It is often useful to get a set to wear (from the RN) to help keep track of what they are doing (inducing VT, ablating, finishing).

Many patients have pacing devices. Feel free to discuss changing the pacing rate if the set rate is too slow for the hemodynamics. For patients with low EFs a low heart rate under anesthesia may not be adequate. The device technician is usually available in person for such cases. The Cardiology fellow can program the device as well.

Atrial Fibrillation ablation:  

This procedure is typically performed for atrial fibrillation or atrial flutter and lasts about 3-4 hours.

Set-up/Anesthetic considerations

    1. Typically need GA due to discomfort caused by the ablation and need for the patient to stay still during a long procedure.

    2. Nurses will start PIV in pre-op.

    3. Patients need an arterialline for the case, if it is difficult to obtain in a radial, the cardiologists can place a femoral. Nurses will use it to check ACTs.

    4. ETT is preferred for the case due to need for specialized temp probe.

    5. A specialized oral temp probe will be provided by the nurses. After placing it in the esophagus leave the stylet in until they verify with fluoroscopy the exact position of it as they use this information to judge if the ablation could potentially cause an esophageal perforation.

    6. They may request on OG also for barium administration to map out the esophagus.

    7. Esosure device to move esophagus out from behind the atria: a minority of cardiologists, (Dr Badhwar and Dr Nguyen) might want you to insert this device via an OG tube, and manipulate the esophagus while they look under fluoro for the position of the esophagus. Check if this device will be needed as soon as the procedure starts so that the OG tube can be placed prior to heparin initiation. The device instructions are appended to this document.

    8. Smaller TV (6-8cc/kg) are preferred to minimize respiratory motion of the myocardium.

    9. After induction, intubation, and TEE is performed paralytic should be avoided. This is so the diaphragm can be stimulated during the ablation procedure after mapping is completed.

    10. Remifentanil can be considered during the ablation procedure to avoid coughing during stimulating parts of the procedure. Fentanyl bolus can also be used.

    11. Several liters of fluid may be given by the cardiologists for this procedure-therefore it is essential to minimize fluids given by the anesthesiologist. Typically, a phenylephrine infusion is given to maintain blood pressure and the goal is to limit fluid for the case to 1 liter or less.

Procedure:  The cardiologists access the RA from the femoral vein and then preform a septal puncture with heparinization to allow access to pulmonary veins. Balloon cryo-ablation is used (balloons in each pulmonary vein to create injury/scar to isolate source of dysrhythmia).

There are two ways this is typically performed- cryoablation or radiofrequency ablation. For cryoablation the ablation of the R pulmonary vein carries a 5-10% risk of phrenic nerve paralysis. Because of this, the cardiologists will typically pace the diaphragm during this portion of the procedure and request that the patient is not paralyzed. Due to the phrenic nerve stimulation patients may cough at this timewhich is why alow dose remifentanyl infusion is typically used.

Radiofrequency ablationrequires fluid (1-2 L typical) administration through the ablation catheter to cool it. (done by the nurses). Lasix is then given at end of the case if fluid balance was excessive.

Risks of procedure: Cardiac perforation/ tamponade, esophageal injury/bleeding, airway bleeding from pulm vein injury (rare). If new hemodynamic instability or narrowing of the pulse pressure presents, notify the cardiologist so they can use their intra-atrial ultrasoundto evaluate for pericardial effusion/tamponade. In case of tamponade, the procedure will be stopped and the nurses will obtain a pericardiocentesis tray. Heparin is reversed with protamine. An interventional cardiologistis called to placea pigtail catheter into the pericardiumto drain the tamponade. The patient is observed and if further drainage is required, CT surgeryis called. The nurses should know who is on for both CT surgery and interventional cardiology before the start of the case.

Atrial Flutter ablation:  

Similar to atrial fibrillation ablation. If the case is listed as typical atrial flutter ablation, it means that the cardiologists do not need extensive mapping for the flutter focus, and the case might be relatively shorter/less complex. For such cases, a urine catheter might not be indicated. Arterial line is at your discretion, but often a NIBP is acceptable.

SVT Ablation:  

Usually done under MAC. Cases typically last 3-4 hrs. Many SVTs are abolished by GA and so limited sedation is preferred, especially during mapping. The first part of the case involves mapping of the myocardium to identify scar and culprit tissue that is initiating the dysrhythmia-light sedation. Typically if MAC, this is performed by using a propofol infusion. Midazolam in small dose can be used in the beginning, and fentanyl for groin puncture. Ketamine 5-10 mg, may help the patient tolerate the procedure. Sometimes the cardiologists will inject isoproterenol to induce the arrhythmia. Unfortunately any movement of the patient during the mapping, ruins the orientation of the map and may require remapping. SVT can be right-sided or left-sided. Left-sided requires septal puncture and heparinization. Risks are same as for atrial fibrillation ablation. Radial arterial line is usually inserted. Urine catheter – depends upon patient and expected duration of procedure.

VT Ablation:  

If VT is particularly difficult to provoke,sedation is used. However, these can be long cases, up to 6hrs in some cases. Patients frequently have poor cardiac function and low EFs. An arterial line is usually needed, as VT is being induced, and BP monitoring becomes important. Avoid fluid overload. If EF is low patients may need inotropic support (dopamine or low dose epinephrine drip). If EF is normal (eg RV dysplasia) could use phenylephrine but be aware of low cardiac output given prolonged VT needed for map (follow pulse pressure, UOP, etc). Consider norepinephrine.

If patient might not tolerate long duration of time under MAC, you can discuss with the interventionalist, a plan to induce GA once their mapping is completed.

Risks: VF arrest (nurses always put on defib pads, cardiologist will defibrillate the patient either with external or internal device). Our goal is to support patient if defibrillation is unsuccessful (usually it is after 2nd shock if first was not). Epi (usually 50-100mcg rather than code dose), Vaso (5-10 units), only if BPis not responding to defib or epi. Perforation/tamponade are possible complications.

Pacemaker placement ("2 chamber": RA and RV lead):  

Generally, these procedures can be done without anesthesia or under MAC unless there is a specific patient need/consideration. If the placement of the generator is in a non-traditional spot, consult with the cardiologist about general anesthesia. Most non-traditional placements will require general anesthesia. Occasionally they will need to test high output pacing and make sure it does not stimulate the phrenic nerve, thus no paralysis is preferred.

ICD placement:  

Can frequently be done without anesthesia or with MAC. Only need brief GA for defibrillator threshold testing (DFT testing) (ie. induction of VF and defibrillation at different energy levels).

Subcutaneous ICD placements usually require defibrillation threshold testing. An arterial line is useful in these cases, particularly in the setting of poor cardiac function. For primary prevention of sudden death (patients with a strong family history of sudden death, but otherwise healthy themselves), some cardiologists are doing superficial parasternal blocks followed by a deep block under vision in the ICD generator pocket area. Such cases could be done with IV sedation.

BiVentricular Pacemaker/ICD:  

Like standard ICD plus a 3rd lead is placed retrograde into the coronary sinus. This lead is threaded retrograde in to a branch coronary vein to allow direct stimulation of the LV. GA is preferred, given length of time it takes to position ICD lead. On average this takes 2-3 hrs. A line is preferred because most patients have low EFs and a conduction delay.

Other general considerations(for both groups):  

Morbidly obese patients:  

The catheterization lab bed is not like a typical surgical bed- it does not allow for reverse Trendelenburg. A troop pillow and additional intubating equipment should be considered when intubating morbidly obese patients. Further, there is a weight limit on the cath lab beds- if you are dealing with a morbidly obese patient that is >300lbs it is best to confirm that the patient meets the weight limit requirement of the cath lab bed before placing them on the bed.

Mitochondrial/Congenital heart disease cases:  

There is a population of patients with mitochondrial diseases and congenital heart diseases that occasionally come through the cath lab. They are starting to expand their adult congenital volume. The cardiac anesthesia group will continue to be involved in these casesand depending on the complexity will assume a role of either a consultant to the MSD anesthesiologist or may find the case requires a cardiac anesthesiologist.

Laser lead extractions:  

The concern is if these are fresh leads being extracted. If these are fresh leads, a back-up plan needs to be clearly defined in terms if the patients may require to emergently go to the operating room and be put on bypass. It is not uncommon to have a level-1 set up in the room and have a cardiac anesthesiologist available.

The risks of "old" leads being extracted is significantly less in regards to complications.

Choice of anesthetic agent:  

Very little evidence exists on the role of individual drugs on EP procedures. However, lidocaineis not considered a good agent to use in these procedures (remember it is an antiarrhythmic!!).

A combination of multiple drugs is generally used in a single patient, making strong conclusions difficult. Many agents including fentanyl, ketamine, dexmedetomidine, midazolam, isoflurane and sevoflurane have been used safely in these procedures. Neither propofol nor isoflurane anesthesia altered sinoatrial node or AV node function in pediatric patients undergoing RFA. (3) Most tachyarrhythmias remained inducible under propofol anesthesia, except for ectopic atrial tachycardia in children that were not inducible in 4 out of 7 children and the procedure could not be accomplished.(4) For Wolff-Parkinson-White ablation, sufentanil-lorazepam had no clinically significant effect on the EP expression of the accessory pathway, however volatile anesthetics, with isoflurane being most significant, increased refractoriness of the accessory and AV pathways. (5)

Changes in management compared to a usual operating room:  

  1. Remember that patient undergoing procedures frequently have defibrillator pads on. The first line of treatment if needed would be to shock the patient out of a rhythm which causes unstable hemodynamics.

  2. If concerned about endotracheal tube placement, fluoroscopy is readily available and can assist with determining the positioning of the endotracheal tube.

  3. If the stylet temperature probe encounters resistance, try not to force it. There have been a couple of instances where the stylet temperature probe has been placed in the trachea and past the pilot balloon of the endotracheal tube.

  4. There is a difficult airway cart in the cath lab PACU. If a surgical airway is needed emergentlyin the PACU, there is a hospital emergency surgical airway team that can be called. On a rare occasion, there may be a situation in the cath lab PACU that may require emergent intubation to secure an airway. One example that may occur is if in a non-anesthesia case, a right heart cath is performed through accessing the right internal jugular vein. After the procedure, the patient coughs and begins to bleed through the access point from the right internal jugular vein in the neck. This may cause airway compromise and the potential for difficulty with intubation.

Further Reading:  

  1. Ashley EMC. Anaesthesia for electrophysiology procedures in the cardiac catheter laboratory. Continuing Education in Anaesthesia, Critical Care & Pain. 2012.

  2. Anderson R, Harukuni I, Sera V. Anesthetic Considerations for Electrophysiologic Procedures. Anesthesiology Clinics, Volume 31, Issue 2, June 2013, Pages 479-489.

  3. Lai LP, Lin JL, Wu MH, et al. Usefulness of intravenous propofol anesthesia for radiofrequency catheter ablation in patients with tachyarrhythmias: infeasibility for pediatric patients with ectopic atrial tachycardia. Pacing Clin Electrophysiol. 1999;22:1358–1364.

  4. Lavoie J, Walsh EP, Burrows FA, et al. Effects of propofol or isoflurane anesthesia on cardiac conduction in children undergoing radiofrequency catheter ablation for tachydysrhythmias. Anesthesiology. 1995;82:884–887.

  5. Sharpe MD, Dobkowski WB, Murkin JM, et al. The electrophysiologic effects of volatile anesthetics and sufentanil on the normal atrioventricular conduction system and accessory pathways in Wolff-Parkinson-White syndrome. Anesthesiology. 1994;80:63–70.

  6. V. Malladi, P.S. Naeini, M. Razavi, C.D. Collard, J.M. Anton, D.A. Tolpin, Endovascular ablation of atrial fibrillation, Anesthesiology, 120 (2014) 1513-1519.

 

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