The Electrogram Analyzer allows users to view and analyze signal data from mapping procedures. It displays graphs of the signal, fast Fourier transform (FFT), continuous wavelet transform (CWT), and CWT inter-spike interval (ISI) analysis. Measurement values from the CWT ISI analysis include minimum, maximum, mean, and standard deviation of intervals between activations. Controls allow sending FFT or CWT values to the results grid for the selected data point.

1. An Overview of the Electrogram Analyzer
The Electrogram Analyzer includes several data analysis features for evaluating and displaying detailed Signal, FFT,
Continuous wavelet (CWT) and CWT ISI graphs. This analyzed FFT or Continuous Wavelet value can then be
transferred to the DF column of the Results Data Grid for the selected data point. The Electrogram Analyzer is
displayed by right-clicking any cell in a row of the Results Data Grid that is populated with Data Point information, and
then clicking Display Signal. The Electrogram Analyzer can display the following data:
n Signal — The signal for the selected data point
n FFT — Fast Fourier Transformation Frequency Spectrum
n CWT — Continuous Wavelet Transform Analysis
n CWT ISI — Continuous Wavelet Transform with Inter-spike Interval Analysis
n RI — Regularity Index
n OI — Organizational Index
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Note: Toolbars, Dialog Boxes and Drop down menus may differ for Review Workstation as not all options / features are available
on the Review Workstation. All references to CLEARSIGN Amplifier throughout this Help System refers to both the original
CLEARSIGN Amplifier and CLEARSIGN II Amplifier.

2. Menus
The following menus are provided in the Electrogram Analyzer:
Options — Provides the following commands: Signal Preconditioning Filtration Options, CWT Options.
Tools — Provides the following commands: Generate Signal Preconditioning Filtration, Generate FFT,
Generate Wavelet Transformation.
Signal Graph
When the Electrogram Analyzer window is opened, a graph appears in the upper region of the Electrogram
Analyzer window. This graph represents the signal (waveform data) associated with Mapping channel for the data
point currently selected in the Results Data Grid.
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FFT/Continuous Wavelet (CWT)/CWT ISI graph area (see Lab Note below)
The lower region of the Electrogram Analyzer contains an area for displaying several additional graphs. Each graph is
displayed by clicking the button (Calculated FFT, Continuous Wavelet (CWT) or CWT ISI) associated with the
graph you want to display.
Clicking the Calculated FFT button displays a graph of the frequency spectrum derived by use of a Fast Fourier
Transform algorithm. An example is shown below.

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Clicking the Continuous Wavelet (CWT) button opens an area for displaying a graph of the continuous wavelet
analysis. An example is shown below.
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Continuous Wavelet Transformation (CWT) analysis is
currently available in research mode only.

4. CWT capabilities - Detection of local activation times using wavelet spectrum and analysis of the set of intervals (ISI).
Clicking the CWT ISI button provides an area for displaying two graphs, one of which displays Inter Spike Interval
(ISI) from CWT values and another that displays ISH Histogram values. A small area between these two graphs is
also provided for displaying a list of calculated values (results of the Inter spike analysis) These results include the
following:
n Min ISI (ms) - minimum interval between detected activations (green squares) in CWT graph
n Max ISI (ms) - maximum interval between detected activations
n Mean ISI (ms) - average interval between detected activations
n SD of ISI (ms) - standard deviation between detected activations
n DF from mean ISI - 1000 divided by the mean ISI. In case of regular activity, this value is equal to "DF from FFT"
n DF from most frequent ISI - another measure of frequency from set of ISI intervals (1000/(most freq ISI)). In
case of non-stationary frequency, this value is equal to the dominant component.
An example is shown below.
Any area of interest in the graphs generated by the Electrogram Analyzer can be zoomed into by left clicking and
dragging the pointer down and to the right to select a portion of the graph.
The default view is easily displayed by clicking and dragging the pointer down and to the left.
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Controls
Sends the FFT value to the DF column for the current data point.

5. Sends the Wavelet value to the DF column of the Results data Grid for the current data point.
Closes the Electrogram Analyzer.
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References
Several papers are listed below that contain additional information about signal analysis methodologies:
n T. Everett, J. Moorman, L. Kok, J. Akar, and D. Haines, “Assessment of Global Atrial Fibrillation Organization to
Optimize Timing of Atrial Defibrillation”, Circulation, vol. 103, pp 2857-2861, 2001.
n M. Hayes, Statistical Digital Processing and Modeling: John Wiley & Sons, 1996.
n P. Stoica and R.L. Moses, Introduction to Spectral Analysis, Englewood Cliffs, NJ, 1997.
n P. D. Welch, “The Use of Fast Fourier Transform for Estimation of Power Spectra: A Method Based on Time
Averaging Over Short Modified Periodograms”, IEEE Transaction on Audio Electroacoustics, vol. AU-15, pp. 70-73,
1967.
n Jason NG, PH.D. and Jeffrey J. Goldberger, M.D., Understanding and Interpreting Dominant Frequency Analysis of
AF Electrograms, J Cardiovasc Electrophysiol, Vol. 18, pp. 680-685, June 2007
n Yoshihide Takahashi, M.D.; Prashanthan Sanders, M.B.B.S., PH.D.; Pierre Jais, M.D.; Meleze Hocini, M.D.; Remi
Dubois, PH.D.; Martin Rotter, M.D.; Thomas Rostock, M.D.; Chrishan J. Nalliah, BS.C.; Frederic Sacher, M.D.;
Jacques Clementy, M.D.; and Michel Haissaguerre, M.D., "Organization of Frequency Spectra of Atrial Fibrillation:
Relevance to Radiofrequency Catheter Ablation", Circulation, J Cardiovasc Electrophysiol, Vol. 17, pp. 1-7, April
2006