Chapter 61. Intracardiac Electrophysiology Studies

• Evaluation of tachycardia mechanism, in preparation for catheter ablation procedure.

• Evaluation of wide QRS tachycardia, where ECG interpretation does not clarify mechanism of tachycardia.

• Evaluation of sudden cardiac arrest.

• Evaluation of unexplained syncope.

• Risk stratification for risk of cardiac arrest in patients with repaired congenital heart disease.

• Evaluation of conduction system, or risk of tachycardia, particularly prior to surgery for congenital heart disease.

• Lack of vascular access.

• Cardiac catheterization laboratory; nursing and technical support staff.

• Biplane fluoroscopy.

• Electrode catheters, usually multiple, with recording equipment.

• Sedation and intravenous access as necessary.

• Cardiac defibrillator.

• Resuscitation medications.

• Vascular injury, peripheral or coronary.

• Bleeding.

• Infection.

• Pneumothorax.

• Cardiac perforation.

• Thromboembolism.

• Initiation of hemodynamically unstable arrhythmia, or conversion of one mechanism of tachycardia into another tachycardia.

• Arrhythmias may require direct current cardioversion or defibrillation.

• Radiation exposure.

• Risk of death: < 0.5%.

• Invasive electrophysiology studies are performed prior to virtually all ablation procedures.

• Patients with unexplained cardiac arrest, particularly with congenital heart disease, may undergo electrophysiologic studies to identify cause and direct therapy.

• In the setting of structural heart disease, electrophysiologic studies may help identify patients at increased risk of sudden cardiac arrest, such as patients with repaired tetralogy of Fallot.

• Patients with cardiac ion channelopathies, such as long QT syndrome, do not generally undergo invasive electrophysiology studies.

• Patient should not have any oral intake for at least 4 hours before the study.

• Sedation is administered; general anesthesia is often preferred for lengthy procedures or for younger patients.

• Intravenous access is necessary, usually femoral venous, often bilaterally and multiple, in addition to internal jugular or subclavian venous access.

• Supine, with protection of airway.

• Arms are positioned at sides for long procedures, to avoid potential brachial plexus injury.

• Adequate padding to avoid pressure injury is needed for extremities and head.

• Shielding of gonads from radiation is necessary.

• Catheters are positioned in atria, at atrioventricular nodal region, and in right ventricular apex for basic procedures.

• Additional catheters are positioned in coronary sinus, coursing posteriorly to mitral valve, to record left atrial activation.

• Left ventricular or esophageal recordings may be added.

• Using sterile preparation with Seldinger percutaneous entry technique into veins or an artery, electrode catheters are advanced to the heart through vascular sheaths, and positioned using fluoroscopy.

• Catheters are connected to recording equipment and filter box to allow electrogram display and recording; real-time and review mode of tracings available.

• Catheter positioning is optimized based on size of electrograms recorded, pacing capture thresholds, and anatomic positioning.

• For diagnostic purposes, pacing may initiate reentrant cardiac arrhythmias, allowing interpretation of mechanism of tachycardia.

• Mapping may be performed to precisely localize critical part of tachycardia circuit, or origin of automatic arrhythmia; performed in ...