T-Wave Alternans Challenge Database

This database is described in

Moody GB, The PhysioNet / Computers in Cardiology Challenge 2008: T-Wave Alternans. Computers in Cardiology 35:505-508; 2008.

Please cite this publication when referencing this material, and also include the standard citation for PhysioNet:

Goldberger AL, Amaral LAN, Glass L, Hausdorff JM, Ivanov PCh, Mark RG, Mietus JE, Moody GB, Peng C-K, Stanley HE. PhysioBank, PhysioToolkit, and PhysioNet: Components of a New Research Resource for Complex Physiologic Signals. Circulation 101(23):e215-e220 [Circulation Electronic Pages; http://circ.ahajournals.org/cgi/content/full/101/23/e215]; 2000 (June 13).

This database has been assembled for the PhysioNet/Computers in Cardiology Challenge 2008. It contains 100 multichannel ECG records sampled at 500 Hz with 16 bit resolution over a ± 32 mV range. The subjects include patients with myocardial infarctions, transient ischemia, ventricular tachyarrhythmias, and other risk factors for sudden cardiac death, as well as healthy controls and synthetic cases with calibrated amounts of T-wave alternans. Specific information about individual records (which was withheld during the challenge) is now available here.

Since these records come from a variety of sources, some of them have been resampled and scaled from original recordings sampled at higher or lower resolution in order to present them in a uniform format here. In most cases, each record contains the standard 12 diagnostic ECG signals, but a few contain only 2 or 3 signals. Each record is approximately two minutes in duration.

Each record consists of 3 files in standard PhysioBank format:

twann.hea: a short (text) header file that specifies the format of the record including the number and names of the signals.
twann.dat: a long (binary) signal file containing the digitized signals.
twann.qrs: a medium-length (binary) annotation file containing the times of occurrence of the QRS complexes within the record. Although a few of the records contain ectopic beats, all beats are marked within the .qrs files as if normal.

For convenience, the entire collection of records in this directory (.hea, .dat, and .qrs files) can be downloaded in a single compressed archive file, twadb.tar.gz (about 72 Mb). Instructions for unpacking .tar.gz archive files are here.

The WFDB Software Package, freely available from this site, contains a wide variety of open-source applications for reading, viewing, reformatting, and analyzing these files and those belonging to other PhysioBank records. You can also write your own software that reads these files using the WFDB library included in the WFDB Software Package. Alternatively, see How to obtain PhysioBank data in text form.

 Name                    Last modified      Size  Description
 Parent Directory                             -   
 ANNOTATORS              21-Apr-2008 10:52   21   list of annotators
 MD5SUMS                 28-Apr-2008 11:34   13K  
 RECORDS                 20-Apr-2008 20:02  600   list of record names
 SHA1SUMS                28-Apr-2008 11:34   15K  
 SHA256SUMS              28-Apr-2008 11:34   23K  
 twa00.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa00.hea               20-Apr-2008 20:02  105   header file
 twa00.qrs               20-Apr-2008 20:02  308   unaudited annotations
 twa01.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa01.hea               20-Apr-2008 20:02  477   header file
 twa01.qrs               21-Apr-2008 08:13  560   unaudited annotations
 twa02.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa02.hea               20-Apr-2008 20:02  108   header file
 twa02.qrs               20-Apr-2008 20:02  836   unaudited annotations
 twa03.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa03.hea               20-Apr-2008 20:02  513   header file
 twa03.qrs               20-Apr-2008 20:02  688   unaudited annotations
 twa04.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa04.hea               20-Apr-2008 20:02  145   header file
 twa04.qrs               20-Apr-2008 20:02  382   unaudited annotations
 twa05.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa05.hea               20-Apr-2008 20:02  109   header file
 twa05.qrs               20-Apr-2008 20:02  908   unaudited annotations
 twa06.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa06.hea               20-Apr-2008 20:02  477   header file
 twa06.qrs               20-Apr-2008 20:02  496   unaudited annotations
 twa07.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa07.hea               20-Apr-2008 20:02  145   header file
 twa07.qrs               20-Apr-2008 20:02  422   unaudited annotations
 twa08.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa08.hea               20-Apr-2008 20:02  107   header file
 twa08.qrs               20-Apr-2008 20:02  420   unaudited annotations
 twa09.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa09.hea               20-Apr-2008 20:02  486   header file
 twa09.qrs               20-Apr-2008 20:02  532   unaudited annotations
 twa10.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa10.hea               21-Apr-2008 09:12  108   header file
 twa10.qrs               20-Apr-2008 20:02  260   unaudited annotations
 twa11.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa11.hea               20-Apr-2008 20:02  510   header file
 twa11.qrs               20-Apr-2008 20:02  540   unaudited annotations
 twa12.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa12.hea               20-Apr-2008 20:02  507   header file
 twa12.qrs               20-Apr-2008 20:02  398   unaudited annotations
 twa13.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa13.hea               20-Apr-2008 20:02  481   header file
 twa13.qrs               20-Apr-2008 20:02  522   unaudited annotations
 twa14.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa14.hea               20-Apr-2008 20:02  144   header file
 twa14.qrs               20-Apr-2008 20:02  564   unaudited annotations
 twa15.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa15.hea               20-Apr-2008 20:02  491   header file
 twa15.qrs               21-Apr-2008 08:28  556   unaudited annotations
 twa16.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa16.hea               20-Apr-2008 20:02  517   header file
 twa16.qrs               21-Apr-2008 08:38  532   unaudited annotations
 twa17.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa17.hea               20-Apr-2008 20:02  481   header file
 twa17.qrs               21-Apr-2008 08:39  582   unaudited annotations
 twa18.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa18.hea               20-Apr-2008 20:02  500   header file
 twa18.qrs               20-Apr-2008 20:02  580   unaudited annotations
 twa19.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa19.hea               20-Apr-2008 20:02  507   header file
 twa19.qrs               20-Apr-2008 20:02  462   unaudited annotations
 twa20.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa20.hea               20-Apr-2008 20:02  509   header file
 twa20.qrs               20-Apr-2008 20:02  526   unaudited annotations
 twa21.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa21.hea               20-Apr-2008 20:02  478   header file
 twa21.qrs               20-Apr-2008 20:02  508   unaudited annotations
 twa22.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa22.hea               20-Apr-2008 20:02  106   header file
 twa22.qrs               20-Apr-2008 20:02  260   unaudited annotations
 twa23.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa23.hea               21-Apr-2008 09:11  105   header file
 twa23.qrs               20-Apr-2008 20:02  556   unaudited annotations
 twa24.dat               21-Apr-2008 08:44  1.4M  digitized signal(s)
 twa24.hea               21-Apr-2008 08:44  516   header file
 twa24.qrs               21-Apr-2008 08:44  338   unaudited annotations
 twa25.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa25.hea               20-Apr-2008 20:02  506   header file
 twa25.qrs               20-Apr-2008 20:02  492   unaudited annotations
 twa26.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa26.hea               20-Apr-2008 20:02  526   header file
 twa26.qrs               20-Apr-2008 20:02  334   unaudited annotations
 twa27.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa27.hea               20-Apr-2008 20:02  522   header file
 twa27.qrs               20-Apr-2008 20:02  386   unaudited annotations
 twa28.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa28.hea               20-Apr-2008 20:02  478   header file
 twa28.qrs               21-Apr-2008 08:53  552   unaudited annotations
 twa29.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa29.hea               20-Apr-2008 20:02  482   header file
 twa29.qrs               21-Apr-2008 08:54  604   unaudited annotations
 twa30.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa30.hea               20-Apr-2008 20:02  494   header file
 twa30.qrs               20-Apr-2008 20:02  534   unaudited annotations
 twa31.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa31.hea               20-Apr-2008 20:02  506   header file
 twa31.qrs               20-Apr-2008 20:02  568   unaudited annotations
 twa32.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa32.hea               20-Apr-2008 20:02  143   header file
 twa32.qrs               20-Apr-2008 20:02  664   unaudited annotations
 twa33.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa33.hea               20-Apr-2008 20:02  484   header file
 twa33.qrs               21-Apr-2008 08:56  604   unaudited annotations
 twa34.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa34.hea               20-Apr-2008 20:02  483   header file
 twa34.qrs               20-Apr-2008 20:02  512   unaudited annotations
 twa35.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa35.hea               20-Apr-2008 20:02  482   header file
 twa35.qrs               20-Apr-2008 20:02  534   unaudited annotations
 twa36.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa36.hea               20-Apr-2008 20:02  497   header file
 twa36.qrs               20-Apr-2008 20:02  590   unaudited annotations
 twa37.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa37.hea               20-Apr-2008 20:02  146   header file
 twa37.qrs               20-Apr-2008 20:02  406   unaudited annotations
 twa38.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa38.hea               20-Apr-2008 20:02  508   header file
 twa38.qrs               20-Apr-2008 20:02  364   unaudited annotations
 twa39.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa39.hea               20-Apr-2008 20:02  518   header file
 twa39.qrs               20-Apr-2008 20:02  650   unaudited annotations
 twa40.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa40.hea               20-Apr-2008 20:02  516   header file
 twa40.qrs               20-Apr-2008 20:02  472   unaudited annotations
 twa41.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa41.hea               20-Apr-2008 20:02  508   header file
 twa41.qrs               20-Apr-2008 20:02  436   unaudited annotations
 twa42.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa42.hea               20-Apr-2008 20:02  506   header file
 twa42.qrs               20-Apr-2008 20:02  480   unaudited annotations
 twa43.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa43.hea               20-Apr-2008 20:02  144   header file
 twa43.qrs               20-Apr-2008 20:02  342   unaudited annotations
 twa44.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa44.hea               20-Apr-2008 20:02  518   header file
 twa44.qrs               20-Apr-2008 20:02  316   unaudited annotations
 twa45.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa45.hea               20-Apr-2008 20:02  103   header file
 twa45.qrs               20-Apr-2008 20:02  454   unaudited annotations
 twa46.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa46.hea               20-Apr-2008 20:02  509   header file
 twa46.qrs               20-Apr-2008 20:02  464   unaudited annotations
 twa47.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa47.hea               20-Apr-2008 20:02  501   header file
 twa47.qrs               20-Apr-2008 20:02  570   unaudited annotations
 twa48.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa48.hea               20-Apr-2008 20:02  505   header file
 twa48.qrs               20-Apr-2008 20:02  526   unaudited annotations
 twa49.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa49.hea               20-Apr-2008 20:02  507   header file
 twa49.qrs               20-Apr-2008 20:02  484   unaudited annotations
 twa50.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa50.hea               20-Apr-2008 20:02  487   header file
 twa50.qrs               20-Apr-2008 20:02  510   unaudited annotations
 twa51.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa51.hea               20-Apr-2008 20:02  487   header file
 twa51.qrs               20-Apr-2008 20:02  524   unaudited annotations
 twa52.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa52.hea               20-Apr-2008 20:02  485   header file
 twa52.qrs               20-Apr-2008 20:02  474   unaudited annotations
 twa53.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa53.hea               20-Apr-2008 20:02  507   header file
 twa53.qrs               20-Apr-2008 20:02  578   unaudited annotations
 twa54.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa54.hea               20-Apr-2008 20:02  509   header file
 twa54.qrs               20-Apr-2008 20:02  570   unaudited annotations
 twa55.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa55.hea               20-Apr-2008 20:02  503   header file
 twa55.qrs               20-Apr-2008 20:02  578   unaudited annotations
 twa56.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa56.hea               20-Apr-2008 20:02  512   header file
 twa56.qrs               20-Apr-2008 20:02  352   unaudited annotations
 twa57.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa57.hea               20-Apr-2008 20:02  146   header file
 twa57.qrs               20-Apr-2008 20:02  400   unaudited annotations
 twa58.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa58.hea               20-Apr-2008 20:02  511   header file
 twa58.qrs               20-Apr-2008 20:02  460   unaudited annotations
 twa59.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa59.hea               20-Apr-2008 20:02  107   header file
 twa59.qrs               20-Apr-2008 20:02  328   unaudited annotations
 twa60.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa60.hea               20-Apr-2008 20:02  504   header file
 twa60.qrs               20-Apr-2008 20:02  482   unaudited annotations
 twa61.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa61.hea               21-Apr-2008 09:10  106   header file
 twa61.qrs               20-Apr-2008 20:02  346   unaudited annotations
 twa62.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa62.hea               21-Apr-2008 09:12  103   header file
 twa62.qrs               20-Apr-2008 20:02  432   unaudited annotations
 twa63.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa63.hea               20-Apr-2008 20:02  103   header file
 twa63.qrs               20-Apr-2008 20:02  346   unaudited annotations
 twa64.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa64.hea               20-Apr-2008 20:02  486   header file
 twa64.qrs               20-Apr-2008 20:02  508   unaudited annotations
 twa65.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa65.hea               20-Apr-2008 20:02  507   header file
 twa65.qrs               20-Apr-2008 20:02  590   unaudited annotations
 twa66.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa66.hea               20-Apr-2008 20:02  504   header file
 twa66.qrs               20-Apr-2008 20:02  472   unaudited annotations
 twa67.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa67.hea               20-Apr-2008 20:02  481   header file
 twa67.qrs               20-Apr-2008 20:02  514   unaudited annotations
 twa68.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa68.hea               20-Apr-2008 20:02  106   header file
 twa68.qrs               20-Apr-2008 20:02  290   unaudited annotations
 twa69.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa69.hea               20-Apr-2008 20:02  479   header file
 twa69.qrs               21-Apr-2008 09:27  546   unaudited annotations
 twa70.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa70.hea               20-Apr-2008 20:02  483   header file
 twa70.qrs               20-Apr-2008 20:02  498   unaudited annotations
 twa71.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa71.hea               21-Apr-2008 09:12  104   header file
 twa71.qrs               20-Apr-2008 20:02  386   unaudited annotations
 twa72.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa72.hea               20-Apr-2008 20:02  481   header file
 twa72.qrs               20-Apr-2008 20:02  536   unaudited annotations
 twa73.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa73.hea               20-Apr-2008 20:02  487   header file
 twa73.qrs               20-Apr-2008 20:02  500   unaudited annotations
 twa74.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa74.hea               20-Apr-2008 20:02  514   header file
 twa74.qrs               20-Apr-2008 20:02  382   unaudited annotations
 twa75.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa75.hea               20-Apr-2008 20:02  513   header file
 twa75.qrs               21-Apr-2008 09:33  490   unaudited annotations
 twa76.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa76.hea               20-Apr-2008 20:02  499   header file
 twa76.qrs               20-Apr-2008 20:02  504   unaudited annotations
 twa77.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa77.hea               20-Apr-2008 20:02  141   header file
 twa77.qrs               20-Apr-2008 20:02  568   unaudited annotations
 twa78.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa78.hea               20-Apr-2008 20:02  486   header file
 twa78.qrs               21-Apr-2008 09:34  586   unaudited annotations
 twa79.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa79.hea               20-Apr-2008 20:02  490   header file
 twa79.qrs               21-Apr-2008 09:38  574   unaudited annotations
 twa80.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa80.hea               20-Apr-2008 20:02  145   header file
 twa80.qrs               20-Apr-2008 20:02  372   unaudited annotations
 twa81.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa81.hea               20-Apr-2008 20:02  490   header file
 twa81.qrs               20-Apr-2008 20:02  516   unaudited annotations
 twa82.dat               20-Apr-2008 20:02  1.5M  digitized signal(s)
 twa82.hea               20-Apr-2008 20:02  496   header file
 twa82.qrs               20-Apr-2008 20:02  524   unaudited annotations
 twa83.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa83.hea               20-Apr-2008 20:02  508   header file
 twa83.qrs               20-Apr-2008 20:02  466   unaudited annotations
 twa84.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa84.hea               20-Apr-2008 20:02  512   header file
 twa84.qrs               20-Apr-2008 20:02  222   unaudited annotations
 twa85.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa85.hea               20-Apr-2008 20:02  146   header file
 twa85.qrs               20-Apr-2008 20:02  418   unaudited annotations
 twa86.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa86.hea               20-Apr-2008 20:02  515   header file
 twa86.qrs               20-Apr-2008 20:02  334   unaudited annotations
 twa87.dat               20-Apr-2008 20:02  1.2M  digitized signal(s)
 twa87.hea               20-Apr-2008 20:02  514   header file
 twa87.qrs               20-Apr-2008 20:02  404   unaudited annotations
 twa88.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa88.hea               20-Apr-2008 20:02  475   header file
 twa88.qrs               21-Apr-2008 09:46  556   unaudited annotations
 twa89.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa89.hea               20-Apr-2008 20:02  141   header file
 twa89.qrs               20-Apr-2008 20:02  388   unaudited annotations
 twa90.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa90.hea               20-Apr-2008 20:02  517   header file
 twa90.qrs               20-Apr-2008 20:02  522   unaudited annotations
 twa91.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa91.hea               20-Apr-2008 20:02  482   header file
 twa91.qrs               21-Apr-2008 09:52  566   unaudited annotations
 twa92.dat               20-Apr-2008 20:02  352K  digitized signal(s)
 twa92.hea               20-Apr-2008 20:02  141   header file
 twa92.qrs               20-Apr-2008 20:02  444   unaudited annotations
 twa93.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa93.hea               21-Apr-2008 09:12  107   header file
 twa93.qrs               20-Apr-2008 20:02  406   unaudited annotations
 twa94.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa94.hea               20-Apr-2008 20:02  514   header file
 twa94.qrs               20-Apr-2008 20:02  512   unaudited annotations
 twa95.dat               20-Apr-2008 20:02  234K  digitized signal(s)
 twa95.hea               20-Apr-2008 20:02  106   header file
 twa95.qrs               20-Apr-2008 20:02  332   unaudited annotations
 twa96.dat               20-Apr-2008 20:02  1.3M  digitized signal(s)
 twa96.hea               20-Apr-2008 20:02  518   header file
 twa96.qrs               20-Apr-2008 20:02  316   unaudited annotations
 twa97.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa97.hea               20-Apr-2008 20:02  495   header file
 twa97.qrs               21-Apr-2008 09:55  562   unaudited annotations
 twa98.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa98.hea               20-Apr-2008 20:02  493   header file
 twa98.qrs               21-Apr-2008 09:56  576   unaudited annotations
 twa99.dat               20-Apr-2008 20:02  1.4M  digitized signal(s)
 twa99.hea               20-Apr-2008 20:02  514   header file
 twa99.qrs               20-Apr-2008 20:02  488   unaudited annotations