Wavelet variance analysis of high-resolution ECG in patients prone to VT/VF during cardiac electrophysiology studies

This study evaluates influence of increased heart rate on beat-to-beat variability of vector magnitude depolarisation signal in patients admitted for cardiac electrophysiology studies. Electrical variability is quantitatively assessed during normal sinus rhythm and during atrial pacing by means of the Morlet wavelet transform variance in high-frequency region of 100 Hz to 250 Hz. Results suggest that pacing increases the electrical variability of QRS-complex more in patients with inducible ventricular tachyarrhythmia than in non-inducible ones. Instead of provoking arrhythmias by more intense stimulation to evaluate risk of VT/VF, more natural perturbation of the system by increasing heart rate and measuring the described parameter may be useful.