Anesthetic considerations for electrophysiology procedures

INTRODUCTION — There is growing use of percutaneous cardiac interventions performed in specialized settings (eg, electrophysiology [EP], cardiac valve, shunt occlusion, and transesophageal echocardiography [TEE] procedures), and some of these procedures require anesthesia care remote from the main operating room (OR).

Selection of an anesthetic technique will be based on procedure-related factors (eg, expected duration and discomfort and risk associated with the procedure), as well as patient-related factors such as inability to remain motionless during the procedure or high risk for oversedation, respiratory arrest, and/or hemodynamic instability due to severe cardiovascular disease or pulmonary comorbidity.

This topic will review anesthetic management of adult patients undergoing procedures in EP suites. A separate topic addresses general considerations and challenges for provision of non-operating room anesthesia (NORA) in an EP suite, TEE suite, or other settings remote from the main OR area. (See "Considerations for non-operating room anesthesia (NORA)", section on 'Anesthetic challenges in non-operating room locations'.)

A separate topic addresses anesthetic management for percutaneous cardiac valve procedures performed in the cardiac catheterization laboratory or a hybrid OR. (See "Anesthesia for percutaneous cardiac valve interventions".)

ELECTROPHYSIOLOGY PROCEDURES: GENERAL CONSIDERATIONS

Preanesthesia consultation — Details regarding standard preanesthesia consultations for cardiac or noncardiac procedures are discussed in other topics. (See "Preoperative evaluation for anesthesia for cardiac surgery" and "Preoperative evaluation for anesthesia for noncardiac surgery".)

Specific patient- and procedure-related considerations — The number of electrophysiology (EP) cases requiring monitored anesthesia care (MAC) or general anesthesia has increased to >50 percent of all cases [1]. Patient- and procedure-related considerations are discussed in advance with members of the interventional electrophysiology (EP) team [1-4]. Specific concerns in this setting may include:

●Patient-related considerations

•Heart failure – Patients undergoing catheter ablation procedures with heart rhythm disorders such as atrial fibrillation (AF) or ventricular tachycardia (VT), or implantation of a cardiac implantable electrical device (CIED) commonly have structural heart disease and heart failure (HF). It is important to minimize the administration of fluids in these patients to avoid volume overload.

•Renal insufficiency – Intravenous (IV) contrast is used for EP procedures in which venous patency is required for placement of intravascular leads (eg, CIED implantation) [5]. In general, the required contrast volumes are lower than needed for coronary angiography. Prevention of contrast-associated acute kidney injury is particularly important in patients with preexisting renal insufficiency. Preventive measures may include minimizing the volume of contrast administered, implementing preventive measures to mitigate effects of contrast on kidney function, or avoiding IV contrast administration by using alternate imaging strategies [5]. (See "Prevention of contrast-associated acute kidney injury related to angiography" and "Complications of diagnostic cardiac catheterization", section on 'Acute renal failure'.)

•History of allergy to IV contrast or other required medications – Use of contrast agents is avoided, if possible, in patients with a prior history of allergic reaction to these agents. If contrast administration is necessary, preventive measures to avoid anaphylaxis are implemented (table 1). (See "Complications of diagnostic cardiac catheterization", section on 'Allergic reactions' and "Patient evaluation prior to oral or iodinated intravenous contrast for computed tomography", section on 'Prevention'.)

Administration of protamine is avoided if a previous reaction to this agent is suspected.

●Procedure-related considerations

•Preoperative antibiotics – IV antibiotic prophylaxis is administered just prior to implantation of CIEDs but is not needed for most catheter ablation procedures. (See "Infections involving cardiac implantable electronic devices: Treatment and prevention", section on 'Antibiotic prophylaxis at device implantation'.)

•Use of radiation – Precautions to minimize radiation are employed. A pregnancy test is obtained on the morning of the procedure for any patient with potential childbearing capacity. (See "Radiation dose and risk of malignancy from cardiovascular imaging".)

•Expected duration of the procedure – Procedure durations in the EP lab vary but are often long and may be difficult to predict. Minimal or moderate sedation may be inadequate for patient comfort and safety during prolonged procedures. (See 'Choice of anesthetic technique' below.)

•Anticipated need for frequent periods of apnea or jet ventilation – (See 'Management of conventional ventilation' below and 'Management of jet ventilation' below.)

•Risk of bleeding – Preoperative type and screen testing is not usually needed for catheter ablation procedures or CIED implantation but should be completed prior to procedures such as transvenous lead extraction that are associated with risk for severe complications. (See "Periprocedural complications of percutaneous coronary intervention", section on 'Retroperitoneal bleeding' and "Atrial fibrillation: Catheter ablation", section on 'Vascular complications'.)

•Exclusion of intracardiac thrombus

-If intra-atrial thrombus is suspected, some centers perform transesophageal echocardiography (TEE) before induction of general anesthesia on the day of the EP procedure or the day before the procedure. However, insertion of a TEE probe to check again for thrombus may be accomplished after induction of general anesthesia. (See 'Monitoring' below and 'Induction' below.)

Suspicion for intra-atrial thrombus may be lower if a patient presents for ablation while in normal sinus rhythm, has been adherent to prescribed oral anticoagulation for an adequate period, and has normal left ventricle (LV) systolic function. In such cases, if cardiac computed tomographic angiography (CTA) has also ruled out left atrium (LA) and LA appendage thrombi, it may be reasonable to forgo TEE. Multiple validation studies have shown excellent sensitivity and negative predictive value of CTA for left atrial thrombus, particularly when delayed-phase protocols are utilized [6].

-If an intraventricular thrombus is suspected, a transthoracic echocardiogram with ultrasound contrast and/or other cardiac imaging (cardiovascular magnetic resonance imaging with contrast or cardiac computed tomography with contrast) may be obtained prior to the procedure. Notably, a TEE examination may not detect intraventricular thrombus, particularly if located in the ventricular apex.

Further discussion of intracardiac thrombus detection is available in separate topics. (See "Echocardiographic evaluation of the atria and appendages" and "Left ventricular thrombus after acute myocardial infarction".)

●Planning the location for recovery – Considerations in planning the location for recovery include anticipated post-procedure care requirements and recovery bed availability. Recovery may be accomplished in the interventional suite recovery area, post-anesthesia care unit, or an intensive care unit.

Management of preoperative medications — Patients receive specific instructions from the EP team regarding their antiarrhythmic and other cardiovascular medications, as well as chronically administered anticoagulant medications. Patients are carefully queried about their preoperative use of medications before the procedure. The EP cardiologist is consulted if there is uncertainty regarding compliance with instructions (eg, recent ingestion of an antiarrhythmic drug that should have been held or missed dose(s) of an oral anticoagulant before a cardioversion) (See "Invasive diagnostic cardiac electrophysiology studies", section on 'Preprocedural evaluation'.)

●Cardiovascular medications – Doses of most chronically administered cardiovascular medications (eg, statins, aspirin) are generally continued during the preoperative period before an EP procedure (see "Perioperative medication management"). However, as directed by the EP team, certain antiarrhythmics that affect atrioventricular (AV) node conduction (eg, calcium channel blockers, digoxin (table 2)) are commonly discontinued several days before an ablation procedure for AV nodal dependent arrhythmias such as AV nodal reentry to allow for induction of the arrhythmia. Other antiarrhythmic drugs such as flecainide, sotalol, and amiodarone are held before ablation procedures for AF and VT [2]. (See "Invasive diagnostic cardiac electrophysiology studies", section on 'Preparation and monitoring'.)

●Antithrombotic agents – Many patients scheduled for EP procedures are receiving anticoagulant and/or antiplatelet therapy [2]. Timing of the most recent doses of anticoagulant or antiplatelet medications is managed by the EP team since these agents increase risk for bleeding during and following interventional procedures. If there is uncertainty about anticoagulation status on the day of the procedure, we obtain coagulation tests (eg, prothrombin time [PT] and international normalized ratio [INR]) so that the EP team can determine whether rescheduling of the EP procedure is necessary.

Monitoring

●Standard monitors – Regardless of whether minimal sedation or general anesthesia is selected, monitoring always includes standard American Society of Anesthesiologists (ASA) monitors including pulse oximetry and capnography to ensure that hypoxia and apnea are avoided (table 3) [7-9]. (See "Basic patient monitoring during anesthesia".)

●TEE – In some cases, a TEE examination is performed shortly after induction (see 'Induction' below) to detect intracardiac thrombus (particularly the LA and LA appendage). As discussed separately, TEE is considered an aerosol-generating procedure, posing potential risk for transmission of coronavirus disease 2019 (COVID-19) if urgent or emergency examination is necessary in a patient with suspected or known active infection. (See "Transesophageal echocardiography: Indications, complications, and normal views", section on 'COVID-19 precautions'.)

●Esophageal temperature probe – For selected ablation procedures performed under general anesthesia, we orally insert an esophageal temperature probe after induction of anesthesia. Esophageal temperature monitoring is a critical safety measure to avoid thermal injury during radiofrequency or cryoenergy ablation in the posterior LA near the esophagus. (See 'Ablation of cardiac arrhythmias' below.)

●Intra-arterial access – We selectively insert an intra-arterial catheter in patients with:

•Significant cardiovascular risk factors such as very low ejection fraction, frequent episodes of malignant arrhythmias, acute coronary syndrome, severe heart failure, or hemodynamic instability

•Arrhythmias with a rapid ventricular response that may preclude accurate monitoring with a blood pressure cuff

•Anticipated need for multiple blood samples to monitor [2,10]:

-Anticoagulation (eg, activated clotting time [ACT] monitoring during heparin administration for procedures involving left heart ablation such as pulmonary vein isolation) (see 'Coagulation management' below)

-Arterial blood gases (ABGs) during jet ventilation (see 'Management of jet ventilation' below)

●Neuromonitoring – We employ neuromonitoring of the processed or unprocessed EEG to guide anesthetic administration, particularly when a total intravenous anesthetic (TIVA) technique is planned (eg, during jet ventilation) (see 'Management of jet ventilation' below), particularly if a neuromuscular blocking agent (NMBA) is to be administered. (See "Accidental awareness during general anesthesia", section on 'Brain monitoring'.)

Choice of anesthetic technique

Minimal or moderate nurse-administered sedation — Minimal or moderate sedation administered by credentialed nursing staff under the direction of the electrophysiologist is appropriate for many EP procedures when neither prolonged procedure duration nor hemodynamic instability are likely (table 4) [11]. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications".)

Monitored anesthesia care — Anesthesia personnel are consulted by the EP team for selected patients with considerations such as moderate to severe anxiety, a potentially difficult airway, or potential hemodynamic instability to provide monitored anesthesia care (MAC) or, in some cases, general anesthesia. (See 'General anesthesia' below.)

A MAC anesthetic technique during an EP procedure involves (see "Monitored anesthesia care in adults"):

●Oxygen administration – Administration of supplemental oxygen by face mask as needed to keep oxygen saturation within normal limits. Standard precautions are employed to minimize risk of a fire, particularly if the oxygen source and the patient’s face are covered under the surgical drapes [12]. (See "Fire safety in the operating room".)

●Anesthetic agents – We typically administer a propofol infusion titrated at 25 to 75 mcg/kg per minute, with or without an initial propofol bolus. A short-acting opioid may be added, usually a remifentanil infusion 0.025 to 0.1 mcg/kg per minute. Reasonable alternatives include small doses of other sedative or analgesic agents (eg, ketamine, midazolam, fentanyl), or a dexmedetomidine infusion to produce sedation with minimal respiratory changes [13-16]. (See "Monitored anesthesia care in adults", section on 'Drugs used for sedation and analgesia for monitored anesthesia care'.)

For portions of certain procedures, the electrophysiologist may request that sedation be minimized so that arrhythmias can be more readily elicited for the diagnostic portions of the procedure.

General anesthesia — Anesthesia personnel are consulted by the EP team to provide general anesthesia for selected procedures including those requiring endotracheal intubation because of planned transesophageal echocardiography (TEE) monitoring throughout the procedure, for procedures that are prolonged, painful, or likely to be compromised by patient movement, that require subcutaneous tunneling of leads, or if the patient cannot lie supine for the duration of the procedure.

Induction

●Induction and airway management – After induction of general anesthesia, an endotracheal tube (ETT) is usually inserted whether conventional or jet ventilation is planned (see 'Management of conventional ventilation' below and 'Management of jet ventilation' below). An NMBA may be administered to facilitate intubation. However, if TEE examination is to be performed to inspect the cardiac chambers before beginning the procedure, then short-acting anesthetic agents and a short-acting NMBA are selected to allow rapid awakening if thrombus is detected since the procedure may be cancelled and rescheduled if intracardiac thrombus is detected. In selected cases, a laryngeal mask airway (LMA) may be inserted after induction of general anesthesia, thereby avoiding administration of an NMBA to facilitate placement of an ETT [17]. In such cases, the TEE probe is placed into the esophagus after induction of anesthesia, followed by insertion and positioning of the LMA.

Notably, administration of any long-acting NMBA is avoided altogether if phrenic nerve stimulation is planned during procedures utilizing cryoballoon ablation of the right-sided pulmonary veins. (See 'Ablation of cardiac arrhythmias' below.)

●Esophageal temperature probe placement – After removal of the TEE probe, an esophageal temperature probe is inserted orally in selected cases with planned radiofrequency ablation in the posterior LA near the esophagus. We avoid insertion of the probe via the nasal route due to the possibility of significant nasal bleeding, particularly in patients who take anticoagulant agents [10]. During the procedure, the electrophysiologist can use fluoroscopy to guide precise positioning of the esophageal probe and facilitate optimal monitoring of esophageal temperature. (See 'Ablation of cardiac arrhythmias' below.)

●Transcutaneous pacing/defibrillator pads – Transcutaneous pacing/defibrillator pads are routinely placed before induction of anesthesia since defibrillation, cardioversion, or transcutaneous pacing may be necessary during the procedure. An external defibrillator with pacing capability should be immediately available. (See "Temporary cardiac pacing" and "Intraoperative advanced cardiac life support (ACLS)".)

●Intravenous access – Adequate IV access must be ensured before the patient's arms are tucked at the sides since the arms will be inaccessible during the procedure. In most cases, a second peripheral IV catheter is inserted before or shortly after induction of general anesthesia. The femoral intravenous sheaths inserted by the electrophysiologist can be used for central venous administration of medications in an emergency, as well as for routine ACT sampling if an arterial catheter is not indicated for hemodynamic monitoring.

Management of conventional ventilation

●Techniques to maintain general anesthesia – During conventional ventilation, general anesthesia may be maintained with a technique that primarily employs either inhalation or IV anesthetics, or a combination of agents administered by both routes [2]. Although many anesthetics cause mild prolongation of the QT interval (>440 ms) or slight depression of sinoatrial (SA) or atrioventricular (AV) nodal function (eg, volatile inhalation anesthetics, opioids, dexmedetomidine, midazolam, etomidate, ketamine), we do not avoid specific agents as these effects are not clinically significant and do not alter arrhythmia inducibility (table 5) [18].

Doses of an NMBA may be administered if necessary to maintain immobility. However, we avoid use of NMBAs if phrenic nerve stimulation (ie, pacing) is planned in order to preserve responsiveness of this nerve. (See 'Ablation of cardiac arrhythmias' below.)

●Standard ventilation management – During standard positive pressure mechanical ventilation, the electrophysiologist may request temporary pauses in respiration (eg, 10 to 60 seconds) during critical periods of the procedure to stabilize the ablation catheter (see 'Ablation of cardiac arrhythmias' below). Following each apneic period, increased minute ventilation may be necessary to avoid hypercarbia, as guided by capnography.

Management of jet ventilation — Some electrophysiologists request high frequency jet ventilation (HFJV) to minimize chest wall excursions during critical periods of an ablation procedure to promote catheter stability [19,20].

Modifications of anesthetic technique during use of HFJV include:

●IV access – A TIVA technique is necessary during the period of jet ventilation because the anesthesia machine is temporarily removed from the breathing circuit, which precludes use of an inhalation agent [2]. We insert a second reliable peripheral IV for separate administration of TIVA agents.

●Intra-arterial access – We typically insert an intra-arterial catheter to facilitate measurement of arterial blood gases (ABGs) before, during, and after the period of jet ventilation. ABGs are particularly important in patients with severe cardiopulmonary disease (eg, heart failure, severe pulmonary disease). Alternatively, adequacy of ventilation in patients with no significant comorbidities can be assessed with venous blood gases (VBGs) obtained by the electrophysiologist from the femoral venous access catheter.

●Neuromonitoring – To minimize risk of awareness during TIVA, we employ neuromonitoring with an unprocessed or processed electroencephalogram (EEG) such as the bispectral index (BIS) or patient state index (PSI). (See "Accidental awareness during general anesthesia", section on 'Total intravenous anesthesia' and "Accidental awareness during general anesthesia", section on 'Brain monitoring'.)

●Maintenance – The electrophysiologist notifies the anesthesiologist several minutes before HFJV will be needed, typically just before puncture of the atrial septum to access the left side of the heart. The anesthesiologist increases anesthetic depth before initiating HFJV since this ventilatory technique stimulates airway reflexes and may cause coughing or bucking. A bolus dose of an opioid (eg, remifentanil 50 to 100 mcg) may also be administered to attenuate sympathetic responses to this airway stimulation.

Adequate anesthetic depth is subsequently maintained with a TIVA technique as long as HFJV is employed. We typically use a propofol infusion at 100 to 150 mcg/kg per minute combined with a short-acting opioid such as a remifentanil infusion at 0.1 to 0.2 mcg/kg per minute. Longer-acting opioids are unnecessary since postoperative pain is minimal. If phrenic nerve pacing is not planned during the procedure, some clinicians also administer a dose of an NMBA. (See "Maintenance of general anesthesia: Overview", section on 'Total intravenous anesthesia'.)

●Jet ventilation management – Management of HFJV for an EP procedure differs somewhat from management of HFJV in other settings (eg, the intensive care unit) (see "High-frequency ventilation in adults", section on 'High-frequency jet ventilation') [20]. Our typical ventilator settings in a patient with average body habitus and without pulmonary comorbidity are:

•Driving pressure – 30 pounds/square inch (psi)

•Frequency of respirations – 100 breaths/minute

•Fraction of inspired oxygen (FiO₂) – 80 percent

•Inspiratory fraction – 30 percent

•Humidity – 50 percent

We continue monitoring end-tidal carbon dioxide (ETCO₂) throughout the period that HFJV is used. A "saw-tooth" appearance of the ETCO₂ waveform is typical (picture 1). ABGs are monitored before and shortly after initiating HFJV, approximately every 30 minutes during HFJV, and again shortly after reestablishing conventional ventilation. If hypercarbia develops, we change ventilator settings to correct the problem by:

•Decreasing the frequency of respirations (eg, from 100 to 80 bpm), which allows more time in the expiratory phase for passive diffusion of CO₂

•Decreasing the inspiratory fraction (eg, from 30 to 25 percent), which increases the expiratory phase

•Increasing the driving pressure (eg, from 30 to 32 psi)

The decision to use HFJV is carefully considered in each individual patient and reevaluated as the EP procedure proceeds. Hypercarbia and/or increased plateau pressure with barotrauma risk may occur in patients with chronic obstructive pulmonary disease (COPD), asthma, or morbid obesity. If these problems cannot be corrected by changing HFJV settings, use of HFJV is abandoned.

After completion of the critical portions of the EP procedure that require absence of lung movement, HFJV is discontinued and conventional ventilation is resumed.

Hemodynamic management — Hypotension requiring treatment with vasopressors may develop during an EP procedure (table 6). Causes include excessive anesthetic depth during non-stimulating portions of catheter-based procedures, hemodynamic instability due to underlying cardiovascular disease, rapid myocardial pacing, and administration of isoproterenol to elicit arrhythmias [10]. Also, mechanical causes such as blood loss and/or pericardial tamponade can occur with a cardiac or vascular perforation during placement of a transvenous lead or manipulation of an intracardiac ablation catheter. All potential causes of a hypotensive episode must be considered, and close communication between the EP and anesthesia teams is necessary to accurately diagnose and appropriately treat hypotension.

Coagulation management — Anticoagulation with heparin is common during left-sided EP procedures [2]. Protocols for heparin administration depend on the specific procedure and institutional and/or electrophysiologist preferences. Typically, monitoring of activated whole blood clotting time (ACT) is employed to achieve a targeted value indicating adequate heparin effect during the procedure, as well as adequate reversal with protamine at the end of the procedure [10]. (See "Invasive diagnostic cardiac electrophysiology studies", section on 'Vascular access and electrode catheter placement'.)

We typically administer protamine prior to intravascular sheath removal. The trachea may be extubated before or after the femoral sheaths are removed at the end of the procedure. However, since coughing after sheath removal may result in significant bleeding and hematoma at the intravascular cannulation site, patients who are likely to cough (eg, those with reactive airways disease) may be extubated with the sheaths still in place.

Postoperative management — We do not routinely administer analgesic agents at the end of the procedure because post procedure pain is uncommon and rarely severe. Some patients complain about lower back pain shortly after extubation, particularly after long cases in a supine position on an imaging table. We treat this with analgesic agents before exiting the procedure room. (See "Approach to the management of acute pain in adults", section on 'Options for managing postoperative analgesia'.)

Patients are typically required to lie flat for a few hours after removal of the large femoral venous and arterial sheaths. Patients who are unable to maintain adequate ventilation and oxygenation in the supine position may remain intubated, mechanically ventilated, and sedated for a few hours after removal of a femoral sheath.

CONSIDERATIONS FOR SPECIFIC PROCEDURES

Ablation of cardiac arrhythmias — Catheter ablation using radiofrequency (RF) or cryothermal energy is employed to treat several types of tachyarrhythmias (table 7) [2,10,21]. Other topics address technical procedural considerations. (See "Overview of catheter ablation of cardiac arrhythmias" and "Catheter ablation for the treatment of atrial fibrillation: Technical considerations for non-electrophysiologists".)

Complications of catheter ablation (eg, cardiac perforation with tamponade, damage to a cardiac valve, arterial injury during vascular access, heart block requiring a permanent pacemaker, myocardial infarction, thromboembolism) are addressed in separate topics [2]. (See "Overview of catheter ablation of cardiac arrhythmias", section on 'Complications' and "Atrial fibrillation: Catheter ablation", section on 'Complications'.)

Types of ablation

●Radiofrequency ablation (RFA) – Considerations influencing anesthetic care include [2]:

•Possible use of high frequency jet ventilation (HFJV) – If the electrophysiologist uses HFJV during critical portions of the procedure, a total intravenous anesthesia (TIVA) technique is necessary. (See 'Management of jet ventilation' above.)

•Risk of esophageal thermal injury – RF energy heats myocardial tissue and can cause thermal injury to adjacent structures such as the esophagus with potential risk of esophageal perforation and development of an atrial-esophageal fistula [22]. To avoid this, the anesthesiologist inserts an esophageal temperature probe, and the electrophysiologist can use fluoroscopy to guide optimal probe position directly behind the cardiac tissue targeted for ablation. Some esophageal temperature probes have multiple thermistors that eliminate the need for repositioning the probe during the procedure. Esophageal temperature is continuously monitored during active ablation attempts to immediately identify a high esophageal temperature and take measures such as terminating RF delivery or minimizing the power and duration of RF delivery to avoid burn injury in the areas adjacent to the esophagus.

Other preventive measures to reduce the risk of esophageal thermal injury during ablation near the esophagus include decreasing the contact force, and esophageal deviation [23].

•Risk of fluid overload – Saline flushing is used to cool the myocardium throughout the RFA procedure; however, this may result in administration of several liters of fluid. The anesthesiologist should minimize intravenous (IV) fluid administration and calculate total fluid balance at frequent intervals (approximately every 30 minutes). If fluid overload is suspected, we administer IV furosemide 20 mg to achieve diuresis. In patients who have heart failure or renal dysfunction, higher doses of furosemide may be required. A foley catheter or external urine collection device are often placed to manage urine output. (See "Use of diuretics in patients with heart failure", section on 'Loop diuretic dosing'.)

●Cryoballoon ablation (CBA) – Considerations influencing anesthetic care include:

•Risk of thermal injury – A balloon-tipped catheter is inserted into each pulmonary vein to deliver cryothermal energy to freeze the adjacent tissue. Phrenic nerve stimulation is used to avoid nerve injury when CBA sites are near this nerve (picture 2). In such cases, we avoid administration of neuromuscular blocking agents (NMBA). If an NMBA was used for endotracheal intubation, we use peripheral nerve stimulation monitoring to confirm resolution of neuromuscular blockade before initiating phrenic nerve stimulation. (See 'Ablation of cardiac arrhythmias' above.)

CBA can also cause thermal injury to the esophagus with potential risk of esophageal perforation and development of an atrial-esophageal fistula [22]. An esophageal temperature probe is inserted by the anesthesiologist, and the electrophysiologist uses fluoroscopy to guide optimal probe position directly behind the cardiac tissue targeted for ablation. As with RFA, esophageal temperature is continuously monitored during active ablation to avoid cryothermal injury.

•Risk of systemic hypothermia – Systemic cooling and alterations in pulmonary gas exchange during occlusion of a pulmonary vein lasting several minutes may result in systemic hypothermia.

Ablation of atrial arrhythmias

●Atrial fibrillation – Atrial fibrillation (AF) ablation may be performed using circumferential point-by-point RFA lesions or a CBA technique to electrically isolate the pulmonary vein ostia from the body of the left atrium (LA), thereby eliminating trigger(s) for AF.

General anesthesia is typically necessary for AF ablation.

●Atrial flutter and other supraventricular tachycardia ablation – Atrial flutter and other supraventricular tachycardia ablation procedures are often performed with moderate sedation administered by a credentialed nurse (see 'Minimal or moderate nurse-administered sedation' above). However, the electrophysiology (EP) team may request an anesthesia team for provision of monitored anesthesia care (MAC) with deeper IV sedation, or general anesthesia for selected cases.

Ablation of ventricular arrhythmias — Patients undergoing ablation for ventricular arrhythmias such as frequent ventricular ectopy or recurrent sustained monomorphic ventricular tachycardia (VT) typically have underlying severe cardiac pathology (eg, ischemic heart disease, congenital heart disease, cardiomyopathy). (See "Overview of catheter ablation of cardiac arrhythmias".)

●Anesthetic choice – Anesthetic management depends on the specific components of the ventricular arrhythmia ablation procedure.

•Programmed electrical stimulation – Programmed electrical stimulation (PES) via electrode catheter is usually performed to induce VT to confirm the diagnosis and locate the site of origin to guide ablation [24]. Noninvasive programmed stimulation (NIPS) of the ventricular arrhythmia may be performed if the patient has an indwelling cardiac implantable electronic device (CIED). For PES followed by cardioversion as needed, only a brief period of unconsciousness is necessary. Similar to the anesthetic technique employed for cardioversion, we typically administer small bolus doses of propofol (with or without small bolus doses of midazolam). (See 'Cardioversion' below.)

•Mapping – In some cases, the electrophysiologist requests a transient period of minimal sedation to enhance the likelihood of arrhythmia induction to permit endocardial and/or epicardial mapping to identify the site of the arrhythmia before induction of general anesthesia.

•Endocardial ablation – In hemodynamically stable patients, the EP team typically requests MAC with IV sedation for endocardial ablation of VT (see "Overview of catheter ablation of cardiac arrhythmias", section on 'Endocardial mapping techniques'). These procedures involve insertion of a catheter through the femoral artery into the aorta and across the aortic valve into the left ventricle (LV). Alternatively, the catheter may be placed in a femoral vein with (atrial) transseptal puncture to access the LV. (See 'Monitored anesthesia care' above.)

In patients with actual or potential hemodynamic instability, the EP team may request general anesthesia with conventional ventilation. (See 'General anesthesia' above and 'Management of conventional ventilation' above.)

•Epicardial ablation – Epicardial access is obtained via a catheter guided into branches of the coronary sinus or using a percutaneous subxiphoid approach. (See "Overview of catheter ablation of cardiac arrhythmias", section on 'Epicardial ventricular mapping'.)

Since pericardial access and catheter manipulation can be painful, the EP team typically requests general anesthesia with conventional ventilation for these procedures. (See 'General anesthesia' above and 'Management of conventional ventilation' above.)

●Other anesthetic considerations include:

•Monitoring during general anesthesia – We typically insert an intra-arterial catheter before or following induction of general anesthesia since hemodynamic instability may develop, particularly if the patient has frequent episodes of malignant arrhythmias, acute coronary syndrome, or severe heart failure.

•Management of hypotension – If hypotension develops it is treated with arrhythmia control (with cardioversion as needed) and vasopressors and/or inotropes as needed administered (table 6). In rare cases, temporary mechanical circulatory support with an intraaortic balloon pump (IABP) or percutaneous LV assist device (LVAD) may be necessary to maintain hemodynamic stability during the procedure. (See "Intraaortic balloon pump counterpulsation" and "Short-term mechanical circulatory assist devices".)

Procedures for cardiac implantable electronic devices

●Risk of complications – Patients undergoing transvenous implantation or explantation of a CIED such as a permanent pacemaker (PM) or implantable cardioverter-defibrillator (ICD) often have risk factors for complications due to ischemic heart disease, congenital heart disease, cardiomyopathy, right ventricular (RV) dysfunction, or pulmonary arterial hypertension [25,26]. In addition, possible procedure-related complications include traumatic injuries caused by perforation of the superior vena cava, right atrium (RA), or RV, resulting in bleeding, cardiac tamponade, or hemothorax. Other possible complications include tricuspid regurgitation, pneumothorax, malignant arrhythmias, or embolization of thrombus or vegetation from the previously implanted leads [27,28]. Details regarding management of these complications are reviewed separately:

•(See "Cardiac implantable electronic device lead removal", section on 'Complications'.)

•(See "Cardiac implantable electronic devices: Periprocedural complications".)

•(See "Subcutaneous implantable cardioverter defibrillators", section on 'Complications'.)

●Procedure location

•CIED implantation – Most CIED implantation procedures are performed in the EP suite. However, percutaneous epicardial lead placement (eg, for a patient with complicated vascular access or active bloodstream infection) is typically performed under general anesthesia in an operating room (OR) or hybrid suite, rather than the EP suite because a lateral mini-thoracotomy or sternotomy is required. (See "Cardiac implantable electronic devices: Periprocedural complications", section on 'Epicardial lead systems'.)

•Explantation of CIED or transvenous lead extractions – Removal of an infected CIED lead is typically performed in an OR hybrid suite.

Transvenous lead extraction procedures are performed with readily available cardiothoracic surgical backup because of the potential for complications [27,28]. Some institutions schedule all lead extractions in a standard or hybrid OR, with the surgeon either scrubbed in or immediately available within the OR suite [28]. At other centers, low-risk extractions may be performed in the EP lab with a designated surgeon on standby in the hospital. However, most high-risk procedures (eg, ICD leads older than five years or pacing leads older than 10 years) are performed in a hybrid OR with dedicated fluoroscopy, participation of a cardiothoracic surgeon, and general anesthesia [28]. (See "Cardiac implantable electronic device lead removal".)

●Placement of transcutaneous pacing/defibrillator pads – Regardless of the selected anesthetic technique or location for the procedure, we place transcutaneous pacing/defibrillator pads on the patient before beginning the procedure and ensure that an external defibrillator with pacing capability is immediately available. (See "Perioperative management of patients with a pacemaker or implantable cardioverter-defibrillator", section on 'Placement of transcutaneous pacing/defibrillator pads'.).

Testing of defibrillation thresholds (ie, inducing ventricular fibrillation (VF) and allowing the CIED to deliver a shock to restore a stable rhythm) is rarely performed since this can cause cardiovascular collapse or refractory shock [29,30]. However, in some cases, the interventionalist will test a newly implanted ICD to confirm successful termination of the arrhythmia. In the event of device failure, immediate defibrillation is accomplished via the transcutaneous defibrillator pads previously placed on the patient.

Temporary hemodynamic support with vasopressor agents is initiated if initial defibrillation shocks are unsuccessful. In rare cases, cardiopulmonary resuscitation (CPR) and advanced cardiac life support (ACLS) are necessary until stable cardiac rhythm and adequate blood pressure are re-established. (See "Advanced cardiac life support (ACLS) in adults".)

●Anesthetic choice for implantation or explantation of CIED and lead system

•Nurse-administered sedation – Electrophysiologists perform some lower-risk procedures with moderate sedation administered by a credentialed nurse and the electrophysiologist. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications" and "Cardiac implantable electronic devices: Periprocedural complications", section on 'Periprocedural monitoring'.)

•Monitored anesthesia care – The anesthesia team is consulted to provide deeper levels of sedation with MAC for selected patients [14]. (See 'Monitored anesthesia care' above.)

•Regional anesthesia – Regional anesthetic techniques may be used to complement other techniques or as an alternative to deep sedation or general anesthesia for high-risk patients. Use of pectoral nerves (PECS) II block has been reported for transvenous ICD placement [31,32]. PECS II, transversus thoracic muscle plane block, and/or serratus anterior plane block have been employed for subcutaneous ICD placement [33,34]. (See "Thoracic nerve block techniques".)

Use of thoracic paravertebral block has also been reported, although sympathectomy-induced hypotension and risk of chronic administration of anticoagulants are concerns [35]. (See "Thoracic paravertebral block procedure guide" and "Neuraxial anesthesia/analgesia techniques in the patient receiving anticoagulant or antiplatelet medication".)

•General anesthesia – General anesthesia with conventional ventilation is usually requested for high-risk cases performed in the OR a hybrid suite, or for prolonged or painful procedures. Examples include the need for percutaneous epicardial lead placement, painful procedures such as tunneling of a subcutaneous ICD lead across the chest wall, removal of an infected CIED lead system and/or pulse generator, or transvenous lead extractions. (See 'General anesthesia' above and 'Management of conventional ventilation' above.)

Specific considerations for these cases include:

-Monitoring – For selected high-risk cases, we insert an intra-arterial catheter and may use transesophageal echocardiography (TEE) monitoring during general anesthesia so that complications can be immediately detected [27,28].

-Intravascular access – Large-bore intravenous (IV) access (eg, a femoral vein) is ensured due to risk for bleeding complications.

-Airway – We typically insert an endotracheal tube (ETT), particularly if airway access will be limited during the procedure. Also, we insert a soft bite-block to protect the patient's teeth and tongue during any defibrillation attempts.

-Positioning – We carefully check final patient positioning to ensure appropriate padding to avoid injury during movements caused by defibrillation shocks.

Cardioversion

●Anesthetic management for cardioversion without TEE examination – Direct current cardioversion without a TEE examination is a very brief procedure (seconds). The anesthetic goal is to provide deep sedation with loss of consciousness (table 4), which should last for only the few seconds required for one or two cardioversion attempts, while avoiding apnea and the need for assisted ventilation.

•Oxygen administration – We administer oxygen via nasal cannulae and/or a mask before and during administration of sedatives or anesthetic agents. Advanced airway equipment should be immediately available because temporary controlled ventilation with a bag and mask may be necessary in some cases. However, the need for laryngoscopy with endotracheal intubation is rare.

•Monitoring

-Transcutaneous pads are positioned on the patient for cardioversion, and these pads also serve as pacing and/or defibrillator pads. Note that when pacing is needed, the ECG leads from the defibrillator must also be attached to the patient.

-We employ capnography to ensure that a prolonged period of apnea is avoided.

•Anesthetic agents – Typically, we administer small bolus doses of propofol (eg, 10 to 50 mg increments) titrated to produce loss of response to verbal commands and loss of eyelash reflex. Small bolus doses of midazolam (eg, 1 to 2 mg) may be added. (See 'Monitored anesthesia care' above.)

●Anesthetic management for cardioversion preceded by TEE examination – In some cases (eg, history of inadequate anticoagulation conferring an increased risk of intracardiac thrombus and embolic stroke), a TEE examination is performed prior to cardioversion. Anesthetic techniques for a TEE examination are described in a separate topic. (See "Considerations for non-operating room anesthesia (NORA)", section on 'Transesophageal echocardiography procedures'.)

●Management of post-cardioversion arrhythmias – After successful cardioversion, most arrhythmias are benign and temporary (eg, bradycardia, ectopic atrial beats). Occasionally, profound persistent post-cardioversion bradycardia necessitates pharmacologic treatment (eg, atropine or epinephrine) or mechanical intervention (eg, transcutaneous pacing or transvenous pacing if the patient has a CIED in place). Rarely, cardioversion may result in a reentrant atrial tachycardia with a rapid ventricular response or sustained VT or VF requiring cardioversion or defibrillation. These complications and their management are discussed separately. (See "Cardioversion for specific arrhythmias", section on 'Complications' and "Cardioversion for specific arrhythmias" and "Advanced cardiac life support (ACLS) in adults".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Cardiac implantable electronic devices".)

SUMMARY AND RECOMMENDATIONS

●Preanesthesia consultation – Preanesthesia consultation includes review of specific patient and procedure-related considerations and management of cardiovascular, antiarrhythmic, and anticoagulant medications. (See 'Preanesthesia consultation' above.)

●Monitoring – In addition to standard monitors including pulse oximetry and capnography (table 3), we insert an intra-arterial catheter in selected patients with high cardiovascular risk or anticipated need for multiple blood samples to monitor anticoagulation or arterial blood gases (ABGs). For procedures involving radiofrequency ablation (RFA) of atrial arrhythmias, we insert an oral esophageal temperature probe to help reduce the risk of esophageal thermal injury. (See 'Monitoring' above and 'Ablation of cardiac arrhythmias' above.)

●Choice of anesthetic techniques for electrophysiology procedures – The choice of anesthetic technique is based on factors including the anticipated duration and discomfort associated with the procedure, risk of hemodynamic instability, and patient factors (eg, difficult airway). Anesthetic techniques for these procedures range from minimal or moderate nurse-administered sedation, to monitored anesthesia care (MAC), to general anesthesia. (See 'Choice of anesthetic technique' above.)

●Ablation procedures for atrial arrhythmias – General anesthesia is typically necessary for atrial fibrillation ablation while the anesthetic technique for other atrial ablation procedures varies depending upon patient and procedural factors. (See 'Ablation of atrial arrhythmias' above.)

•Risks of radiofrequency ablation – Risks include esophageal thermal injury (monitored with an esophageal temperature probe) and fluid overload.

•Risk of cryoballoon ablation – Risks include phrenic nerve injury (monitored with phrenic nerve stimulation (picture 2)) and hypothermia.

●Ablation of recurrent ventricular tachycardia (VT) – (See 'Ablation of ventricular arrhythmias' above.)

•Endocardial ablation – MAC is typical, but general anesthesia may be selected for patients with actual or potential hemodynamic instability.

•Epicardial ablation – General anesthesia is employed for epicardial ablations involving percutaneous subxiphoid puncture for epicardial access.

●Procedures for implantable cardioverter-defibrillator (ICD) devices and lead systems – The choice of anesthetic technique is based upon patient and procedure specific considerations:

•MAC with deeper levels of sedation is necessary for some patients.

•A regional anesthetic may be selected for subcutaneous ICD placement in patients with limited vascular access and/or high risk for deep sedation.

•General anesthesia is employed for selected high-risk cases. We suggest endotracheal intubation and insertion of a soft bite-block to protect teeth and tongue during defibrillation attempts (Grade 2C).

●Cardioversion – We suggest administration of small titrated bolus doses of propofol (eg, 10 to 50 mg increments) to produce brief deep sedation with loss of consciousness lasting only a few seconds during one or two cardioversion attempts (Grade 2C). Small bolus doses of midazolam (eg, 1 to 2 mg) may be added. (See 'Cardioversion' above.)

ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Wendy L Gross, MD, and Kathleen Evangelista, MS, CRNA, who contributed to an earlier version of this topic review.