Noninvasive Assessment of Atrioventricular Nodal Function: Effect of Rate-Control Drugs during Atrial Fibrillation

• Background: During atrial fibrillation (AF), conventional electrophysiological techniques for assessment of refractory period or conduction velocity of the atrioventricular (AV) node cannot be used. We aimed at evaluating changes in AV nodal properties during administration of tecadenoson and esmolol using a novel ECG-based method. Methods: Fourteen patients (age 58 +/- 8 years, 10 men) with AF were randomly assigned to either 75 or 300 mu g intravenous tecadenoson. After tecadenoson wash-out, patients received esmolol continuously (100 mu g/kg per min for 10 mins, then 50 mu g/kg per min for 50 mins). Atrial fibrillatory rate (AFR) and heart rate (HR) were assessed in 15-min segments. Using the novel method, we assessed the absolute refractory periods of the slow and fast pathways (aRPs and aRPf) of the AV node to produce an estimate of the functional refractory period. Results: During esmolol infusion, AFR and HR were significantly decreased and the absolute refractory period was significantly prolonged in both pathways (aRPs: 387 +/- 73 vs 409 +/- 62 ms, P < 0.05; aRPf: 490 +/- 80 vs 529 +/- 58 ms, P < 0.05). During both tecadenoson doses, HR decreased significantly and AFR was unchanged. Both aRPs and aRPf were prolonged for a 75 mu g dose (aRPs: 322 +/- 97 vs 476 +/- 75 ms, P < 0.05; aRPf: 456 +/- 102 vs 512 +/- 55 ms, P < 0.05) whereas a trend toward prolongation was observed for a 300 mu g dose. Conclusions: The estimated parameters reflect expected changes in AV nodal properties, i.e., slower conduction through the AV node for tecadenoson and prolongation of the AV node refractory period for esmolol. Thus, the proposed approach may be used to assess drug effects on the AV node in AF patients.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Kardiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Cardiac and Cardiovascular Systems (hsv//eng)

Nyckelord

atrioventricular node

atrial fibrillation

functional refractory

period

tecadenoson

esmolol

Publikations- och innehållstyp

art (ämneskategori)

ref (ämneskategori)