[Electric programmed ventricular stimulation using a permanent cardiac pacing system--a noninvasive method in...

Complex forms of ventricular arrhythmias often occur in patients with an implanted permanent cardiac pacing system. Some of the pacemakers are provided with software which allows electrophysiological testing of the cardiac conduction system by coupling with an external diagnostic pacemaker via their programmer. This method is non-invasive.

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 and higher). 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 ventricular arrhythmias were induced in 42% patients (n = 11), in this subgroup 55% (n = 6) was non-sustained ventricular tachycardia, 36% (n = 4) sustained ventricular flutter, 9% (n = 1) sustained ventricular tachycardia. Patients with non-sustained ventricular tachycardia were treated with beta-blockers, in the others the effective therapy was selected according to electrophysiological testing (amiodarone in 4 patients, ICD in 1 patient). During a 24-month follow-up the overall mortality was 7.7% (n = 2), sudden death mortality was 3.8% (n = 1).

Programmed ventricular stimulation performed by a permanent cardiac pacing system is a simple and above all non-invasive method with no need for fluoroscopy. It can be repeated several times. It is not possible to pace from the right ventricle outflow tract. This is the main disadvantage. Nevertheless, by using non-invasive risk 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 considered an alternative screening method and a standard part of the investigation of the algorithm in patients with a previously implanted pacemaker.