Electrophysiology Procedures

Educational Objectives

The goal of this program is to improve the anesthetic management of patients undergoing electrophysiologic and neuroradiologic procedures. After hearing and assimilating this program, the clinician will be better able to:

1. Explain techniques used for cardiac procedures in the electrophysiology laboratory.

2. Recognize risks associated with placement of defibrillators and pacemakers.

 

Summary

Electrophysiology procedures (EP): most common procedures include cardioversion (with or without transesophageal echocardiography [TEE]), placement of pacemakers and defibrillators, and cardiac ablations; most procedures done under local anesthesia plus monitored anesthesia care; planned general anesthesia (GA) used for small proportion; complications — infection; hypotension; pneumothorax; congestive heart failure; cardiac perforation or tamponade

Cardioversion: defibrillator patches usually placed anterior to posterior (sternum to spine); differs from setup for cardiac arrest (defibrillation of ventricle); right atrium generally right parasternal, and left atrium on top of spine; for ventricular tachycardia (VT) or fibrillation (VF), patches placed at base and apex of heart; equipment should be set to synchronize cardioversion with QRS complex (which avoids shocking on T wave, which can cause ventricular arrhythmias); TEE — used to detect intracardiac thrombi in patients who have had insufficient anticoagulation; if thrombus seen, cardioversion must be delayed until clot resolves with anticoagulation; complications include airway and trauma to soft tissue structures when probe passed; postcardioversion arrhythmia — may occur as long pause after cardioversion (especially with sick sinus syndrome), or if atrial fibrillation (AF) suppressed with β-blockers or calcium channel blockers; brief periods of asystole or significant sinus bradycardia may occur (often resolves within several seconds; however, transcutaneous pacing may be required); monitor for VT or VF if defibrillation performed improperly; all defibrillators automatically return to default unsynchronized mode after delivering synchronized shock

Pacemakers and defibrillators: typically placed subcutaneously, below clavicle; wires exit device and enter heart via shoulder vein; set up technique and procedure for pacemaker and defibrillator essentially same (may be placed in subpectoral space if patient, eg, extremely thin, has fragile skin); access via puncture of subclavian vein or cephalic vein cutdown procedure; wires moved via vein to heart under fluoroscopic guidance; leads typically fixed into heart muscle chamber with 2- to 3-mm corkscrew (covered by endothelium and scar tissue after ≈1 yr); perforation — may occur if screw placed in very thin area; may cause sudden tamponade; appendage area less likely to perforate; lateral free wall more likely affected; hypotension and fluoroscopic images of motion of cardiac silhouette helpful for diagnosis; motion (often vigorous) of leads with no movement of cardiac silhouette may indicate tense pericardium due to tamponade; access — cauterizer (Bovie) needed (caution necessary because of high oxygen use); intravenous (IV) contrast or ultrasonography may be needed to gain access to veins; GA used only rarely for standard pacemaker or defibrillator placement

Resynchronization: biventricular implantable cardiac defibrillator used; typically for patients with heart failure, poor ejection fraction, and/or bundle branch block; simultaneous pumping of left and right sides preferable if ejection fraction poor; patients with significant heart failure and bundle branch blocks paced from right and left ventricles; access into coronary sinus needed; venography usually obtained; place additional lead into coronary sinus (epicardial) after venography and fluoroscopic imaging; right atrial and ventricular leads placed in true heart chambers; left ventricle lead epicardial because leaving device in chamber on left side may result in microemboli and stroke

Subcutaneous implantable cardioverter-defibrillator: has no intravascular component; may be considered wearable automated external defibrillator (AED; based on same technology); device subcutaneous; part of shock vector placed at midaxillary line; single lead from ICD tunneled under skin and placed parasternally; device and lead act as paddles from base to apex; senses arrhythmia as with AED; computer algorithm accurately distinguishes true VT or VF from other arrhythmias; false interpretation of rhythms equal to that of intracardiac cardiac devices; tunneling — small incision made at bottom of sternum; tool passes through subcutaneous tissue; silk tie attached and used to pull lead up and through incision point; lead anchored with sutures at tip and base of sternum; device sutured in place

Defibrillation testing: implants induce VF or VT by shocking on T wave or producing high-frequency burst pulse; goal to determine whether device accurately detects VF and successfully delivers shock that restores sinus rhythm; tests at energy lower than device’s maximum; if consistently successful at low energy, device should succeed in real-world situations at maximum energy; magnets — causes blind pacing to occur in pacemaker; shocks disabled on ICD, but device maintains standard pacing function

Ablations: performed for all supraventricular tachycardias (SVT; atrioventricular [AV] nodal reentry tachycardia, AV reentry tachycardia [Wolf-Parkinson-White syndrome], atrial tachycardia, AV node ablation with permanent pacemaker, AF, and VT); wires placed in veins and sent to heart under fluoroscopy; each wire has multiple electrodes, each of which has positive and negative; recordings of electricity and stimulation of heart possible; goal to trigger arrhythmia, then pinpoint location of origin; wire delivers radiofrequency that ablates source of arrhythmia; wires at fixed curve or steerable (stiffness varies; perforation possible); wires placed in different locations in heart to guide physician to area causing tachycardia; access — one or both femoral veins; depending on complexity of arrhythmia, additional wires may be needed; left atrial ablations require transseptal puncture; intracardiac echocardiographic guidance used to locate needle as it crosses atrial septum (tamponade and effusions possible); esophageal temperature probe needed to avoid esophageal damage during left atrial ablation (especially for AF)

Specific indications: atrial flutter — 15% to 20% on left side (more complex procedure); right-sided ablation usually more stable procedure; AF — requires crossing from right to left side; more catheters used to look for signals in left atrium; higher-energy catheter required; more areas along pulmonary veins require ablation

Complications: 0.5°C increase in esophageal temperature may indicate esophageal damage; atrial-esophageal fistula — rare; air entering left atrium (rather than vomiting of blood) signals catastrophic consequences

VT ablation: uses 3-dimensional computer-assisted guidance of catheter; catheters use voltage to distinguish living from dead tissue; islands of dead tissue surrounded by live tissue can generate VT; cauterization to connect areas and isolate islands can minimize or exclude VT; usually used as adjunct therapy for patients not helped by antiarrhythmics, with defibrillators that have delivered multiple shocks

Questions and answers: use of lidocaine — no difference for device implants; for EP studies, depends on rhythm being studied; should not change outcome for AF or atrial flutter; however, lidocaine can interfere with induction; may hinder ability to trigger arrhythmia if patient presents in sinus rhythm; defibrillation when device present — device should tolerate electric shocks; manufacturers advise maximizing distance (2-3 in) from device; if it received direct shock, check device afterward to rule out short circuit or loss of function

 

 

 

Readings

Disclosures

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the planning committee to disclose relevant financial relationships within the past 12 months that might create any personal conflicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this lecture, members of the faculty and planning committee reported nothing to disclose.

Acknowledgements

Dr. Tan was recorded at Albany Medical College’s Anesthesiology Autumn Update and Review, held on September 12-13, 2014, in Saratoga Springs, NY, and sponsored by Albany Medical College’s Department of Anesthesiology, the Office of Continuing Medical Education, and the Albany Medical Center Provider Unit. For information on upcoming CME meetings from Albany Medical College, please visit AMC.edu/academic/CME. The Audio Digest Foundation thanks the speaker and the sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

AN564501

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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