What is the procedure for an Electrophysiology (EPS) study and after an ablation?

Electrophysiology Study and Post-Ablation Procedure

An electrophysiology (EPS) study involves the placement of electrode catheters in multiple cardiac chambers to record intracardiac electrical signals and perform programmed electrical stimulation, while ablation is a therapeutic procedure that follows diagnosis to treat identified arrhythmias. 1

Electrophysiology Study Procedure

Preparation and Setup

• EPS requires careful preprocedural assessment to ensure the patient is stable and able to tolerate the procedure 1
• Absolute contraindications include unstable angina, bacteremia/septicemia, acute decompensated heart failure not caused by arrhythmia, major bleeding disorders, and lower extremity venous thrombosis (if femoral access is planned) 1

Catheter Placement and Recording

• Multiple electrode catheters are placed in cardiac chambers for pacing and recording 1
• Catheter design and placement sites are determined by the suspected arrhythmia 1
• Typically, each catheter has multiple electrode poles for both recording and local stimulation 1
• A standard configuration may include 2-3 diagnostic catheters and an additional mapping catheter if ablation is anticipated 2

Signal Processing and Analysis

• Intracardiac signals are acquired, amplified, filtered, displayed, and analyzed in real-time or stored for offline review 1
• Mapping techniques are used to determine activation sequences during arrhythmias 1
• Analysis includes evaluating responses of arrhythmias to various pacing techniques 1

Diagnostic Applications

• EPSs help clarify electrocardiographic phenomena or explain symptoms possibly due to transient arrhythmias 1
• They determine mechanisms and characteristics of supraventricular tachycardias 1
• EPSs assess drug responses and help select patients for non-pharmacological treatments 1
• They evaluate patients' predisposition for spontaneously occurring arrhythmias when symptoms suggest undocumented arrhythmias 1

Imaging Considerations

• Fluoroscopy has traditionally been the primary imaging modality for EPS 1
• Alternative imaging systems like electroanatomic 3D mapping and intracardiac echocardiography can reduce or eliminate fluoroscopy exposure 1
• The "as low as reasonably achievable" (ALARA) principle is used to minimize radiation exposure 1

Post-Ablation Procedure and Management

Immediate Post-Procedure Care

• Patients are monitored for complications including bleeding, vascular issues, and arrhythmia recurrence 3, 4
• Vital signs and access sites are regularly assessed 4
• Most procedures are performed on an elective basis with same-day discharge for uncomplicated cases 1, 4

Follow-Up and Monitoring

• Systematic follow-up is essential to assess procedural success and detect recurrences 3
• Continuous monitoring with implantable cardiac monitors may be used in selected cases to detect asymptomatic recurrences 3
• Approximately 46% of arrhythmia recurrences may be asymptomatic, highlighting the importance of objective monitoring 3

Success Rates and Outcomes

• Overall success rates for radiofrequency ablation range from 93-99% depending on arrhythmia type 2, 4
• Recurrence rates are approximately 4-5% and are highest in the first 4-6 weeks post-ablation 2, 3
• Freedom from arrhythmia recurrence at 12 months is approximately 60% 3

Potential Complications

• Major complications are rare (0.6-3.9%) and may include pulmonary embolism, pericardial effusion, or AV node block 2, 4
• No mortality has been reported in most series 4

Patient Selection Considerations

• Five key predictors for successful SVT induction and ablation include: characteristic EKG recording of SVT, termination with adenosine, termination with vagal maneuvers, documented SVT ≥30 seconds on monitor, and pre-excitation on baseline EKG 5
• Patients with at least one of these features have a significantly higher probability of successful SVT induction and ablation 5
• In younger patients, selective rather than routine EPS may be appropriate 6

Common Pitfalls and Caveats

• Not all patient-activated episodes during monitoring are true arrhythmias (only 66% in one study) 3
• Relying solely on patient symptoms may miss asymptomatic recurrences 3
• Inadequate mapping may lead to unsuccessful ablation or recurrence 1
• Failure to recognize anatomical variations can increase procedural risk 1
• The highest risk of recurrence is within the first 4-6 weeks post-ablation, requiring careful monitoring during this period 3