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  • • 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 preparation for ...

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