An electrocardiogram (ECG or EKG) is a graphical recording of the changes occurring in the electrical potentials between different sites on the skin as a result of cardiac activity. The electrical activity of the heart is a sequence of depolarizations and repolarizations. Depolarization occurs when the cardiac cells, which are electrically polarized, lose their internal negativity. The spread of depolarization travels from cell to cell, producing a wave of depolarization across the entire heart. This wave represents a flow of electricity that can be detected by electrodes placed on the surface of the body. Once depolarization is complete, the cardiac cells are restored to their resting potential, a process called repolarization. This flow of energy takes on the form of the ECG wave, and is characterized by an initial P wave, followed by the QRS complex, and then the T wave. The P wave is associated with depolarization of the atria, the QRS complex is associated with depolarization of the ventricles, and the T wave with repolarization of the ventricles. Ventricular Late Potentials (VLPs, also called Ventricular Delayed Potentials) are small-amplitude, short-duration waves that occur after the QRS complex and are precursors to cardiac arrhythmias.
Use AcqKnowledge® software to apply signal averaging on the ECG signal to detect VLPs. To perform a VLP measurement on an ECG recording, use off-line averaging to trigger on the R-wave peaks and average the time delta of 209 ms before to 200 ms after the occurrence of each peak. AcqKnowledge measurement tools can calculate the duration and Root Mean Square (rms) values of the VLPs. AcqKnowledge also simplifies other ECG Analysis with powerful, fully automated routines for use post ECG recording: use the ECG averaging function to evaluate changes in the ECG complex before, during, and after exercise or dosing; perform heart rate variability (HRV) analysis; measure respiratory sinus arrhythmia (RSA); and more... http://www.biopac.com/ecg-cardiology
