... databases:¹

Sources: ECRI, 5200 Butler Pike, Plymouth Meeting, PA 19462 USA (AHA DB); PhysioNet (http://physionet.org/) (MIT, NST, CU DB; and ESC DB for non-commercial use); Alessandro Taddei, CNR Institute of Clinical Physiology, G. Pasquinucci Heart Hospital, via Aurelia Sud, 54100 Massa, Italy (ESC DB for commercial use).

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... Practice.²

Testing and Reporting Performance Results of Ventricular Arrhythmia Detection Algorithms. Publication AAMI ECAR (1987); succeeded by ANSI/AAMI EC57:1998, available from AAMI, 1110 N Glebe Road, Suite 220, Arlington, VA 22201 USA.

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... devices.³

American National Standard for Ambulatory Electrocardiographs. Publication ANSI/AAMI EC38:1998; available from AAMI (address above).

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... board⁴

Source: Microstar Laboratories, http://www.mstarlabs.com/. External analog anti-aliasing filters (to reduce “staircasing”) and attenuators (to obtain patient-level signals) may also be required, depending on the system to be evaluated. DAP boards can also be used with sample to create new database records.

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... associated.⁵

Times in annotation and signal files are usually expressed as sample numbers (the number of samples in the signal file that precede the sample in question).

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... annotation.⁶

Test annotations that include heart rate or ST measurements require substantially more storage. getann and putann can also use the original AHA DB format (containing fixed-length annotations, 16 bytes each), but this format should not be used for evaluations of devices that incorporate ST analysis functions, since the space available for the aux data is too small to store ST measurements.

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... frequency.⁷

The obvious alternative, using xform to rewrite the reference annotation files at the time the signal files are resampled, should not be used in a formal evaluation. Because of the possibility that resampling the reference annotation files might result in moving reference annotations into or out of the test period, or changing the lengths of episodes, doing so might produce results that could not be directly compared with those obtained in a standard evaluation.

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... sources.⁸

See, for example, the European ST-T Database Directory, pp. vi-vii, supplied with the ESC DB; or Taddei, A., et al., “The European ST-T database: development, distribution, and use”, Computers in Cardiology 17:177-180 (1990).

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... zero!⁹

For certain types of HRV or RRV measurements (though not for heart rate measurements), this is a potential problem. One solution is to add a small positive offset to any measurement with an expected zero mean. It is within the letter, though not the spirit, of the standard protocol, to add a very large number in such a case, so as to make the error percentage arbitrarily small. The mean value of the reference measurements must be reported; this should serve as a disincentive to this sort of creative abuse of the standard. An honest approach might be to add an offset on the order of the expected standard deviation of the individual measurements.

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... error.¹⁰

mxm is not restricted to comparison of heart rate measurements; if other types of measurements are available, they may be compared in the same manner as heart rates by mxm.

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... style="font-family:monospace">atr”)¹¹

Annotation files for any given record are distinguished by annotator names, which correspond to the “extension” of the file name. The reference annotation files supplied with the databases have the annotator name “atr” (originally “atruth” because “a” was intended to indicate the file type, and “truth” because ... well, because the annotations are supposed to be The Truth).

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... record.¹²

stm.out contains one line for each ST deviation measurement that was compared; in this example, stm.out would be empty since the reference annotation files of the MIT DB do not contain ST deviation measurements.

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... style="font-family:monospace">wave¹³

wave (for FreeBSD, Linux, Mac OS X, Solaris, SunOS, and Windows) are included in the WFDB Software Package.

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Updated 10 June 2022