• 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.
• 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.
• Cardiac perforation.
• 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
• 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
• 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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