ELEKTRICKÁ PROGRAMOVANÁ STIMULACE KOMORPROVÁDĚNÁ PROSTŘEDNICTVÍM TRVALÉHOKARDIOSTIMULAČNÍHO SYSTÉMU - NEINVAZIVNÍMETODA V ARYTMOLOGII

Electrical Programmed Ventricular Stimulation via a Permanent CardiacPacing System - a Non-invasive Method in Arrhythmology

Background.
Complex forms of ventricular arrhythmias often occur in patients with an implanted permanentcardiac pacing system. Some of the pacemakers are provided with software which allows electrophysiological testingof the cardiac conduction system by coupling with an external diagnostic pacemaker via their programmer. Thismethod is non-invasive.Methods and Results. In a group of 26 patients (19 males, 7 females) with an implanted pacemaker (Paragon III,Synchrony III, Sensorithm - all Pacesetter) complex ventricular arrhythmias were observed (class Lown IVa andhigher). In these patients the electrical stability of the myocardium was tested by the described method (protocol:incremental pacing 90 - 220 bpm, pacing drives 110 bpm and 140 bpm with 1 - 3 extrastimuli). Complex ventriculararrhythmias were induced in 42 % patients (n = 11), in this subgroup 55 % (n = 6) was non-sustained ventriculartachycardia, 36 % (n = 4) sustained ventricular flutter, 9 % (n = 1) sustained ventricular tachycardia. Patients withnon-sustained ventricular tachycardia were treated with beta-blockers, in the others the effective therapy was selectedaccording to electrophysiological testing (amiodarone in 4 patients, ICD in 1 patient). During a 24-month follow-upthe overall mortality was 7.7 % (n = 2), sudden death mortality was 3.8 % (n = 1).Conclusions. Programmed ventricular stimulation performed by a permanent cardiac pacing system is a simpleand above all non-invasive method with no need for fluoroscopy. It can be repeated several times. It is not possibleto pace from the right ventricle outflow tract. This is the main disadvantage. Nevertheless, by using non-invasiverisk stratification methods (echocardiography, signal averaged ECG, heart rate variability, baroreflex sensitivity,dispersion of QT interval) the patients in need of an invasive study can be identified. This method can be consideredan alternative screening method and a standard part of the investigation of the algorithm in patients with a previouslyimplanted pacemaker.

Key words:
ventricular arrhythmias, sudden cardiac death, permanent cardiac pacing, programmed ventricularstimulation.