Fig 2. Illustration of global QRS onset and local T wave landmarks detection.
Global R peak is detected using a Pan-Tompkins algorithm on the ECGRMS signal. The global QRS onset is thereafter detected as a peak in the second derivative of the ECGRMS within a certain window preceding the global R peak. The local T peak (Tpk) is detected as the maximum or minimal peak between R+50ms and R+0.7RR. Thereafter, the tangent trough the point of maximum deflection between Tpk and Tpk+0.3RR is calculated from the first derivative. The intersection between this tangent and the baseline is detected as the local end of the T wave (Tend). Tpk = T-wave peak, Tend = T-wave end, RMS = root mean square, SecDer = second derivative, ms = milliseconds.