What is the role of electrophysiologic (EP) studies in the workup of sinus node dysfunction (SND)?

Updated: Nov 30, 2018
  • Author: Bharat K Kantharia, MD, FRCP, FAHA, FACC, FESC, FHRS; Chief Editor: Mikhael F El-Chami, MD  more...
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Answer

Invasive electrophysiologic (EP) studies are rarely used for the evaluation of sinus node dysfunction (SND) because of their limited sensitivity in eliciting bradyarrhythmias as well as due to the widespread availability of diagnostic options for long-term monitoring. However, in patients with suspected SND who also describe sustained episodes of tachyarrhythmias, EP studies may be helpful in an effort to identify a tachycardia (eg, atrial tachycardia) that would be potentially curable with ablation. [28] Nevertheless, invasive EP studies may be performed in the following situations involving symptomatic patients [28] :

  • Those without ECG findings suggestive of SND and no other evident cause for their symptoms

  • Those in whom ECG events are compatible with SND but fail to correlate with symptoms

  • Those with SND who have sustained episodes of tachycardia that may be amenable to ablation

  • Those with syncope or near syncope who have bundle branch or bifascicular block; such patients may require invasive EP evaluation of the sinoatrial (SA) node, the atrioventricular (AV) node, and the infranodal His-bundle-Purkinje system function. EP testing that shows SA nodal dysfunction allows for the selection of appropriate therapy in up to 50% of these patients.

  • Those with syncope or near syncope who have ventricular arrhythmias may require EP study to assess for inducibility of ventricular tachyarrhythmias

The salient aspects of EP studies that aid in eliciting a bradyarrhythmic abnormality include assessment of the SA node recovery time, SA conduction time (SACT), and the SN and atrial tissue refractory periods.


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