NEW TOOLS FOR ELECTRICAL AND HAEMODYNAMIC MONITORING OF TACHYARRHYTHMIA EPISODES IN PACEMAKER PATIENTS

AIMS. Assessing tachyarrhythmia nature and haemodynamic impact by a dual-chamber pacing system. METHODS. In addition to conventional atrial and ventricular electrograms, a multipolar electric signal is derived by the pacemaker Eos DR (Medico, Italy) using the whole set of electrodes available in dual-chamber pacing (intracardiac ECG: iECG). The iECG waveform represents the activity of the whole heart, reflects the QRS duration and features different morphology according to the impulse conduction pattern. The device can detect moreover the electric impedance between right atrium and ventricle (transvalvular impedance: TVI). It increases during the ejection and decreases with ventricular filling, such fluctuation being related with the effectiveness of the pump function. In order to establish whether iECG and TVI can provide diagnostic indications in the event of a tachycardia, we have studied the response of these signals to the induction of different arrhythmias during EP procedures in 40 patients. RESULTS. The iECG evaluation allowed prompt discrimination of ventricular (VT) and supraventricular tachycardias (SVT), since any VT entailed a clear-cut modification in the ventricular component of the waveform (Fig. 1), while the signal morphology was not altered with respect to sinus rhythm in case of SVTs with physiological AV conduction (Fig. 2). The amplitude of TVI fluctuation was reduced to 66 ± 11% and 74 ± 6% of basal value, respectively, in the presence of SVTs or tolerated VTs. In contrast, non-tolerated VTs decreased the TVI amplitude below 40% and increased the signal variability. Ventricular fibrillation resulted in the absence of TVI fluctuation. CONCLUSIONS. Reliable tachycardia characterization is achieved by iECG and TVI analysis, suggesting their potential value as new diagnostic tools in the follow-up of pacemaker patients.