Acute Effects of a Class IA Antiarrhythmic Drug on the Ventricular Evoked Response Amplitude in Patients with Cardiac Pacemakers

Abstract

Some newer cardiac pacemakers are able to control the efficacy of the ventricular pacing pulse beat by beat and to adjust the ventricular output to the actual pacing threshold. This capture verification is based on the detection of the ventricular evoked response amplitude, which has to be detected immediately after the pacing pulse. The sensitivity of the pacemaker to detect the evoked response amplitude must be adjusted individually to avoid the simultaneous detection of lead polarization. The aim of the present study was to evaluate the acute effects of a class IA antiarrhythmic drug on the evoked response amplitude and polarization in 13 pacemaker patients. The implanted pacemaker was the VVIR pacemaker Regency (St. Jude Medical), which provides the automatic capture verification algorithm Autocapture. The patients received 50 mg of ajmaline intravenously within 1 min. The evoked response amplitude and polarization were measured before and 2, 4, 6 and 8 min after ajmaline injection. The evoked response amplitude significantly decreased from 8.0 ± 4.0 mV to a minimum value of 6.4 ± 3.1 mV 2 min after drug administration. The decrease remained significant from the end of the application up to 6 min. The recommended sensitivity setting for the evoked response significantly (p < 0.05) decreased from 4.0 ± 2.3 mV before to 3.1 ± 1.3 mV 2 min after administration. No significant changes were observed for polarization. After the ajmaline application in 2 patients, the pacemaker recommended the deactivation of Autocapture for 9 min in 1 patient and 12 min in the other. The reasons were a decrease in the evoked response amplitude from 3.1 to 1.9 mV and from 9.0 to 5.7 mV, respectively, with a polarization ranging to about 3.0 mV. In conclusion, the ajmaline injection decreased the evoked response amplitude for some minutes. These findings indicate that antiarrhythmic drugs can alter the automatic capture verification function.

Electrical Performance and Automatic Capture Characteristics of a 3.5‐mm2 Passive Fixation Lead during 1‐Year Follow‐Up

“…Activation of AutoCapture™ algorithm can be influenced by body position and exercise, 12 as well as by class IA antiarrhythmic drugs such as ajmaline, 13 but seems to be primarily affected by the mechanical properties rather than by the electrophysiology of the heart 8 . By definition, lead polarization is a hardware constant and is dependent on the surface material and structure of the lead, but might be influenced by changes at the contact area of the lead tip to the myocardium.…”

Automatic Ventricular Threshold Measurement in Children with Epicardial Pacing Leads

“…The sensing of evoked response worked well, and the thresholds remained stable in those of our patients (n = 6) who were on chronic antiarrhythmic medication. The effect of antiarrhythmic drugs has been assessed with AutoCapture; ajmaline injection has decreased the evoked response amplitude for a few minutes after injection 13 . On the other hand, no significant effect was found on chronic ventricular pacing threshold after intravenous or oral administration of sotalol or propranolol 14 .…”

Effects of Rhythm and Rate-Controlling Drugs in Patients With Permanent His-Bundle Pacing

“…Arrhythmias are common in patients with pacemakers and may require management with antiarrhythmic drugs (AADs), which may affect the cardiac conduction system (1)(2)(3). Previous studies (4)(5)(6)(7) have reported that some AADs affect atrial and ventricular pacing threshold and impedance.…”