Modifications to Pan-Tompkins Algorithm for QRS detection, compensating for left ventricular atrophy as seen in 3-lead ECG signals
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Lengthened Ventricular Depolarization >> Unchanged QRS sequence but increased QT interval >> wider T-wave
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Left Ventricular Atrophy >> Higher amplitude T-wave
The effects on the left ventricle necessitate changes in the algorithm to better distinguish R peaks from T peaks.
This algorithm modifies this implementation of the Pan-Tompkins QRS detection algorithm.
1. Remove DC component correction
2. New difference function on lowpass filter
The cascaded band pass described in the 1985 paper removes 5-12Hz, albeit 5-15 was intended. Transfer function determined using Filter Builder in Matlab. New passband is 7-12Hz.
Difference Function:
3. 5-Point Stencil Differentiation
Replaced the numerical differentiation using the central difference method (I guess a 3-point stencil??) with a slight modification to the 5-point used in the original. The 5-point is marginally less efficient (still in constant time) but more accurate. I also recalculated the difference equation and realized a few coefficients were different. I compared the amplitude response of both and they seem to be linear between 0-30Hz. I decided to implement mine because of the work I put into realizing that Taylor expansions from Calc II are actually useful, and in the interest of learning something.
Difference Function:
Its even possible to calculate error:
