SEMIA, version 3.0.1, is a tool for viewing time series of diagnostic and morphology parameters of long-term ambulatory recordings, and ST segment annotations with their corresponding ECG waveforms of the Long-Term ST Database (LTST DB). SEMIA was created during the development of the LTST DB, a project supported by Medtronic, Inc. (Minneapolis, MN, USA) and Zymed, Inc. (Camarillo, CA, USA).
If you have not already installed the WFDB software package and the XView toolkit, do so now.
If you are running under GNU/Linux, you may not need to compile SEMIA. Try running the precompiled version of SEMIA available here. (You will still need to have installed WFDB and XView in order to do this successfully.)
If you need to compile SEMIA, make a directory for the SEMIA sources, then copy all files from this directory into it. (For convenience, you may download this gzip-compressed tar archive of all files in this directory rather than downloading the individual files.)
Enter your directory of SEMIA sources and type 'make'.
You may encounter many warnings related to improperly formatted comments in XView #include files. These warnings may be ignored. If you wish to eliminate them, download and apply this patch (read and follow the instructions at the beginning of the patch to see how to apply it).
When 'make' finishes, copy semia into a directory in your PATH, and copy semia.opt and semia.hlp into the directory where you wish to use SEMIA.
To run SEMIA successfully, the following files of the LTST DB are needed in the current working directory:
The last three of these files are contained within the .tsr.zip files in the LTST DB directory on PhysioNet (or on the "Subset" CD-ROM). Download the .tsr.zip file and unpack it using a command such as:
In addition, you will need copies of semia.opt (a text file containing SEMIA's options) and semia.hlp (a text file containing on-line help for SEMIA) in the current working directory, as noted above.
Run SEMIA by typing "semia". Click on the "Help" button to view SEMIA's on-line manual. To open a record, click on "Open", then enter the record name (snnnnn only; do not include .hea or any other suffix in the record name). Depending on the speed of your system, it may take up to a minute for SEMIA to load the data after you click "OK".
Once the data have been loaded, several buttons that were initially inactive become available for use. Each of them ( "Lead0", "Lead1", "Lead2", "Data", and "KL") opens a window when clicked. ("Lead2" remains inactive unless you have opened a record with 3 ECG signals.)
Fine time series or functions are those obtained on average heart beats after noise detection during preprocessing phase. Raw time series or functions are those after resampling and smoothing of fine functions.
ST segment annotations are: global reference, local references that define the ST reference function, ST segment annotations indicating ischemic and heart-rate related ST episodes (beginnings, extrema, ends), axis shift annotations, conduction change annotations, noise annotations, and annotations indicating unreadable intervals (beginnings, ends).
Three different display modes for "Lead" windows are possible:
The ECG signal corresponding to current active reference annotation is displayed in the upper part of the "Data" window.
Time series displayed in the "Lead" windows can be examined by pointing them using mouse cursor or setting the Marker at the time instance of interest. The corresponding ECG signal is displayed in the lower part of the "Data" window.
ST segment annotations can be examined using the Exm option. The examined ST annotation becomes the currently active annotation, and its corresponding ECG signal is displayed in the lower part of the "Data" window as well.
The time scale may be adjusted to permit between 1 minute and 96 hours of data to be seen at once. Time series from "other" ECG leads may be overlaid in each "Lead" window.
The center heart beat in each ECG trace is the beat average over the chosen time window. ECG signals from "other" ECG leads may be overlaid.
The ST segment or QRS complex distance function (Mahalanobis distance function) can be overlaid in the KL window.