Since the 1980s, there have been dramatic advances in clinical electrophysiology procedures to diagnose and treat cardiac arrhythmias with catheter ablation. Electrophysiologic studies (EPS) generally refer to the catheterization procedure that provides diagnostic information. An EPS is often combined with catheter ablation to treat the identified arrhythmia.
Diagnostic EPS are performed to diagnose an arrhythmia when the diagnosis has not been obtained with noninvasive techniques or as part of an ablation procedure to treat the arrhythmia. EPS can be performed when an arrhythmia is suspected, but symptoms are intermittent and electrocardiographic (ECG) monitoring has not captured the symptomatic rhythm or there is concern that the arrhythmia may be life threatening, as in a patient with structural heart disease and syncope. Diagnostic EPS provides information about cardiac automaticity and conduction (sinus node, atrioventricular [AV] node, and His-Purkinje function) as well as inducible arrhythmias. Programmed electrical stimulation is performed to attempt to induce suspected or documented arrhythmias. EPS can help to detect arrhythmia causes of syncope and distinguish ventricular tachycardia (VT) from supraventricular tachycardia (SVC) with aberrancy (see Fig. 44–2C) and has a role in assessing the risk of ventricular arrhythmias in patients with known or suspected diseases associated with a risk of sudden death. Common uses of EPS are summarized in Table 44–1.
Table 44–1. Diagnostic Electrophysiologic Studies |Favorite Table|Download (.pdf)
Table 44–1. Diagnostic Electrophysiologic Studies
|Suspected or documented bradyarrhythmias|
|Sinus node function|
- Tests the response of the sinus node to atrial pacing.
- The most common is the sinus node recovery time.
- The interval between the last paced beat and next sinus beat.
- Normal <1.5 s.
- Uses: Although it is well standardized, sinus node function is markedly influenced by autonomic tone such that sensitivity is limited.
- Long-term ambulatory monitoring is likely more effective for diagnosing symptomatic sinus node disease that is not apparent on short-term monitoring.
|AV node function|
- The AH interval reflects the conduction time through the AV node (normal, 60-125 ms).
- During atrial pacing, the rate at which AV block (typically AV Wenckebach conduction) occurs is a marker of AV node function (normal >110-120 beats/min).
- As with the sinus node, autonomic tone influences AV node function.
- Long-term ambulatory monitoring is more effective for diagnosing symptomatic AV node disease that is not apparent on short-term ECG recordings.
|His-Purkinje system conduction|
- The HV interval is the conduction time from His bundle activation to earliest ventricular activation (normal, 35-55 ms).
- Severe prolongation (>100 ms) is often seen in patients with episodic AV block below the AV node, which usually occurs as a Mobitz II mechanism.
- Infranodal block may also occur during atrial pacing.
- A short HV interval is seen in ventricular preexcitation due to an accessory pathway.
|Suspected or documented tachycardias: inducible arrhythmias|
|Paroxysmal supraventricular tachycardias|
- AV nodal reentry
- AV reentry using an accessory pathway
- Atrial tachycardia
- Atrial fibrillation (may be nonspecific)
- Atrial flutter (may be nonspecific)
- Sustained: Lasting >30 s or requiring ...