Cardiology > Electrophysiology Procedures  

Background 

I) Definition 

Electrophysiology (EP) procedures are specialized cardiac interventions performed to diagnose and treat abnormal heart rhythms (arrhythmias). These procedures involve the use of intracardiac catheters and electrical recordings to evaluate the heart’s conduction system and identify arrhythmogenic foci. Therapeutic interventions such as catheter ablation, pacemaker or implantable cardioverter-defibrillator (ICD) implantation, and conduction system modulation are often performed during EP studies. 

II) Classification/Types 

By Purpose: 

• • Diagnostic EP Study (EPS): 
    Evaluates the electrical conduction system, identifies arrhythmias, and guides therapy. 

• • Therapeutic Procedures: 

• • Catheter Ablation: Targets and eliminates arrhythmogenic tissue. 

• • Pacemaker Implantation: Treats bradyarrhythmias. 

• • ICD Implantation: Prevents sudden cardiac death from ventricular arrhythmias. 

• • Cardiac Resynchronization Therapy (CRT): Used in heart failure patients with conduction delay. 

By Access: 

• • Transvenous: Via femoral, subclavian, or internal jugular veins. 

• • Epicardial (Surgical): When endocardial access is not feasible. 

By Arrhythmia Type: 

• • Supraventricular arrhythmias (e.g., AVNRT, atrial flutter, WPW) 

• • Ventricular arrhythmias (e.g., VT, VF) 

• • Conduction disorders (e.g., AV block, sinus node dysfunction) 

Pathophysiology 

Cardiac arrhythmias result from abnormal impulse formation (enhanced automaticity, triggered activity) or abnormal impulse conduction (reentry). Electrophysiologic disorders may be due to structural heart disease, ischemia, fibrosis, congenital abnormalities, or ion channelopathies. EP studies replicate arrhythmias through programmed electrical stimulation and mapping to localize abnormal tissue, allowing for precise treatment such as ablation or device placement. 

Epidemiology 

• • Atrial fibrillation is the most common sustained arrhythmia, affecting ~2–3% of adults globally. 

• • Supraventricular tachycardias (SVT) have a prevalence of 2.25 per 1,000. 

• • Ventricular arrhythmias are a leading cause of sudden cardiac death, especially in patients with structural heart disease. 

• • EP procedures are increasingly performed due to advancements in technology and aging populations. 

Etiology 

I) Causes 

Primary Electrical Disorders: 

• • Wolff-Parkinson-White syndrome 

• • Long QT syndrome 

• • Brugada syndrome 

• • Catecholaminergic polymorphic VT 

Structural Heart Disease: 

• • Myocardial infarction 

• • Cardiomyopathies (hypertrophic, dilated) 

• • Valvular disease 

• • Congenital heart disease 

Other Factors: 

• • Electrolyte disturbances 

• • Drug toxicity (e.g., digoxin, antiarrhythmics) 

• • Post-surgical scarring 

II) Risk Factors 

• • Coronary artery disease 

• • Heart failure with reduced ejection fraction 

• • Family history of arrhythmia or sudden cardiac death 

• • Syncope of unknown cause 

• • Palpitations or documented arrhythmias 

Clinical Presentation 

I) History (Symptoms) 

• • Palpitations 

• • Syncope or presyncope 

• • Fatigue 

• • Dyspnea 

• • Sudden cardiac arrest (in ventricular arrhythmias) 

• • Intermittent chest pain (rarely) 

II) Physical Exam (Signs) 

• • Irregular or rapid pulse 

• • Cannon A waves (in AV dissociation) 

• • Variable intensity of heart sounds 

• • Signs of heart failure (edema, JVD, rales) 

Differential Diagnosis (DDx) 

• • Vasovagal syncope 

• • Structural heart disease (e.g., aortic stenosis) 

• • Seizure 

• • Anxiety/panic attacks 

• • Drug-induced arrhythmia 

• • Electrolyte imbalance 

Diagnostic Tests 

Initial Evaluation 

• 12-lead ECG: Identify rhythm, conduction delays, pre-excitation, QT interval. 

• Holter monitor or event recorder: Capture intermittent arrhythmias. 

• Echocardiogram: Evaluate cardiac structure and function. 

• Stress test: Induce exercise-related arrhythmias. 

Specialized Evaluation 

• • Electrophysiology Study (EPS): Invasive procedure to map conduction pathways and induce arrhythmias. 

• • Electroanatomic mapping (3D mapping): Used during ablation to localize arrhythmogenic foci. 

• • Implantable loop recorder: For long-term rhythm monitoring. 

Treatment 

I) Acute Management 

• • Pharmacologic rate/rhythm control: Beta-blockers, calcium channel blockers, antiarrhythmics (amiodarone, sotalol). 

• • Cardioversion: Electrical or pharmacologic for unstable tachyarrhythmias. 

• • Temporary pacing: For symptomatic bradycardia. 

II) Chronic Management 

• • Catheter Ablation: Curative in many supraventricular and some ventricular arrhythmias. 

• • Pacemaker Placement: For bradycardia or AV block. 

• • ICD Placement: For secondary prevention post-cardiac arrest or primary prevention in high-risk patients. 

• • CRT: Improves symptoms and survival in patients with LBBB and HFrEF. 

• • Lifestyle and medication optimization. 

Medications 

Device Therapy 

• • Pacemaker: Maintains heart rate in bradycardia or conduction block. 

• • ICD: Detects and terminates life-threatening ventricular arrhythmias. 

• • CRT (Biventricular pacing): Synchronizes ventricular contraction in select HF patients. 

Patient Education, Screening, Vaccines 

• • Educate on symptoms of arrhythmias and when to seek care. 

• • Discuss potential complications of procedures (e.g., bleeding, perforation, recurrence). 

• • Screen for inherited arrhythmias in family members. 

• • Encourage healthy lifestyle: diet, exercise, avoiding stimulants. 

• • Recommend influenza and pneumococcal vaccination for heart failure patients. 

Consults/Referrals 

• • Electrophysiologist: For EPS, ablation, or device implantation. 

• • Genetic Counseling: In inherited arrhythmia syndromes. 

• • Heart Failure Specialist: For CRT candidates. 

• • Cardiac Surgery: If surgical ablation or epicardial lead placement is needed. 

Follow-Up 

Short-Term 

• • Monitor for post-procedural complications (hematoma, infection). 

• • Device interrogation if implanted. 

• • Medication adjustment as needed. 

Long-Term 

• • Regular device checks (pacemaker/ICD). 

• • Monitor arrhythmia recurrence with ECG or Holter. 

• • Cardiac rehabilitation and lifestyle counseling. 

• • Family screening in inherited cases. 

Prognosis 

• • Ablation of SVT has success rates >90%. 

• • ICD therapy reduces mortality in high-risk populations. 

• • CRT improves survival and quality of life in eligible HF patients. 

• • Prognosis varies by arrhythmia type, structural disease, and patient compliance.