The MIT-BIH Arrhythmia Database was the first generally available set of standard test material for evaluation of arrhythmia detectors, and it has been used for that purpose as well as for basic research into cardiac dynamics at about 500 sites worldwide since 1980. It has lived a far longer life than any of its creators ever expected. Together with the American Heart Association Database, it played an interesting role in stimulating manufacturers of arrhythmia analyzers to compete on the basis of objectively measurable performance, and much of the current appreciation of the value of common databases, both for basic research and for medical device development and evaluation, can be attributed to this experience. In this article, we briefly review the history of the database, describe its contents, discuss what we have learned about database design and construction, and take a look at some of the later projects that have been stimulated by both the successes and the limitations of the MIT-BIH Arrhythmia Database.

The impact of the MIT-BIH Arrhythmia Database

This consensus document provides an up-to-date account of the various methods available for the investigation of chronic venous insufficiency of the lower limbs (CVI), with an outline of their history, usefulness, and limitations. CVI is characterized by symptoms or signs produced by venous hypertension as a result of structural or functional abnormalities of veins. The most frequent causes of CVI are primary abnormalities of the venous wall and the valves and secondary changes due to previous venous thrombosis that can lead to reflux, obstruction, or both. Because the history and clinical examination will not always indicate the nature and extent of the underlying abnormality (anatomic extent, pathology, and cause), a number of diagnostic investigations have been developed that can elucidate whether there is calf muscle pump dysfunction and determine the anatomic extent and severity of obstruction or reflux. The difficulty in deciding which investigations to use and how to interpret the results has stimulated the development of this consensus document. The aim of this document was to provide an account of these tests, with an outline of their usefulness and limitations and indications of which patients should be subjected to the tests and when and of what clinical decisions can be made. This document was written primarily for the clinician who would like to learn the latest approaches to the investigation of patients with CVI and the new applications that have emerged from recent research, as well as for the novice who is embarking on venous research. Care has been taken to indicate which methods have entered the clinical arena and which are mainly used for research. The foundation for this consensus document was laid by the faculty at a meeting held under the auspices of the American Venous Forum, the Cardiovascular Disease Educational and Research Trust, the European Society of Vascular Surgery, the International Angiology Scientific Activity Congress Organization, the International Union of Angiology, and the Union Internationale de Phlebologie at the Abbaye des Vaux de Cernay, France, on March 5 to 9, 1997. Subsequent input by co-opted faculty members and revisions in 1998 and 1999 have ensured a document that provides an up-to-date account of the various methods available for the investigation of CVI.

Investigation of Chronic Venous Insufficiency A Consensus Statement

Guidelines for pre-operative cardiac risk assessment and perioperative cardiac management in non-cardiac surgery.

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Guidelines for pre-operative cardiac risk assessment and perioperative cardiac management in non-cardiac surgery

We examined the prevalence and prognostic importance of silent myocardial ischemia detected by continuous electrocardiographic monitoring in 70 patients with unstable angina. All the patients received intensive medical treatment with nitrates, beta-blockers, and calcium-channel blockers. Continuous electrocardiographic recordings were made during the first two days in the coronary care unit to quantify the frequency and duration of asymptomatic ischemic episodes, defined as a transient ST-segment shift of 1 mm or more. Thirty-seven patients (Group 1) had at least one episode of silent ischemia, and the other 33 patients had no silent ischemia (Group 2). Over the subsequent month, myocardial infarction occurred in 6 patients in Group 1 and in only 1 in Group 2 (P less than 0.01); bypass surgery or angioplasty was required for recurrent symptomatic angina in 10 patients in Group 1 and only 3 in Group 2 (P = 0.02). Survival-curve analysis demonstrated that silent ischemia was associated with these outcomes (P less than 0.002), and multivariate analysis showed that silent ischemia was the best predictor of these outcomes among the 15 variables tested (P less than 0.002). Patients in Group 1 with 60 minutes or more of silent ischemia per 24 hours had a worse prognosis than those with under 60 minutes per 24 hours (P = 0.04). Silent ischemia occurred in more than 50 percent of our patients with unstable angina, despite intensive medical therapy, and it identified a subset who were at high risk for early unfavorable outcomes.

Silent ischemia as a marker for early unfavorable outcomes in patients with unstable angina.

Presents a QT database designed for evaluation of algorithms that detect waveform boundaries in the ECG. The database consists of 105 fifteen-minute excerpts of two-channel ECG Holter recordings, chosen to include a broad variety of QRS and ST-T morphologies. Waveform boundaries for a subset of beats in these recordings have been manually determined by expert annotators using an interactive graphic display to view both signals simultaneously and to insert the annotations. Examples of each morphology were included in this subset of annotated beats; at least 30 beats in each record, 3622 beats in all, were manually annotated in the database. In 11 records, two independent sets of annotations have been included, to allow inter-observer variability studies. The QT Database is available on a CD-ROM in the format previously used for the MIT-BIH Arrhythmia Database and the European ST-T Database, from which some of the recordings in the QT Database have been obtained.

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A database for evaluation of algorithms for measurement of QT and other waveform intervals in the ECG

Vasospastic ischemic mechanism of frequent asymptomatic transient ST-T changes during continuous electrocardiographic monitoring in selected unstable angina patients

The European project for the development of an ST-T annotated database originated from the 'Concerted Action' on ambulatory monitoring, set up by the European Community in 1985. The goal was to define an electrocardiographic (ECG) database for assessing the quality of ambulatory ECG monitoring (AECG) systems. Thirteen research groups from 8 countries continued providing AEGG tapes and annotating beat-by-beat the selected 2-channel records, each 2 hours in duration. ST segment and T-wave changes were identified and their onset, offset and peak beats annotated in addition to QRSs, beat types, rhythm and signal quality changes. The first set of 50 records was completed and stored on compact-disk ROM. It includes more than 200 ST segment and almost 300 T-wave changes. In cooperation with the developers of the Massachusetts Institute of Technology (MIT)-Boston's Beth Israel Hospital (BIH) arrhythmia database, the annotation scheme was devised to be consistent with both MIT-BIH and American Heart Association (AHA) formats. >

The European ST-T database: development, distribution and use

Visual monitoring at the central station of coronary care units (CCUs) may not adequately assess the presence and frequency of transient asymptomatic ST segment changes in patients with unstable angina. We have performed continuous 24-h electrocardiographic recordings over a total period of 50 days in 10 patients admitted to our CCU with frequent attacks of angina at rest. Over the corresponding period, at the central monitoring station (6 beds), the nursing-staff detected only 31 transient ischaemic episodes (27 with ST elevation, 4 with depression, 9 of which were asymptomatic). By contrast the retrospective analogue analysis of tapes identified 213 ischaemic episodes: 143 with ST elevation (greater than or equal to 0.2 mV) and 70 with ST depression (greater than or equal to 0.2 mV); usual CCU monitoring failed to report changes during 13 episodes (8 with ST elevation, 5 with depression) accompanied by anginal pain. When the tapes were played back in real time on a CCU monitoring scope, a cardiologist (who had the option of interrupting the play-back whenever tired) recognized 48% of the episodes when presented in groups of 4 and randomly positioned on the screen together with 2 other electrocardiographic tracings not related to the study; he recognized 92% of the episodes when only one ECG was presented on the screen. Thus conventional visual monitoring in a CCU considerably underestimates the incidence of transient ischaemic ST segment changes, some of which were accompanied by pain. This low rate of detection is the result of the presentation on the central monitoring station of several ECGs and of fatigue.

Unreliability of conventional visual electrocardiographic monitoring for detection of transient ST segment changes in a coronary care unit.

In 1985, the European Community set up a 'Concerted Action on Ambulatory Monitoring', whose goal was to define an ECG (electrocardiography) database as a reference for assessing the quality of ambulatory ECG monitoring (AECG) analyzers. Since it is now recognized that ST-T changes are highly relevant for the diagnosis of ischemic heart disease, it was agreed that the project should concentrate on setting up a standard for annotating ST-T changes. The pilot study, completed at the end of 1986, set up a small prototype database. After the project ended, it was decided that the interest shown by research groups and manufacturers warranted developing the full database. Thirteen groups from eight countries agreed to provide AECG tapes and to contribute to the annotations. So far, 106 AECG records, out of 175 submitted, have been admitted to the database and 96 have each been annotated by two different groups. Disagreements between the annotations have been analyzed for estimation of reliability. The first release of the database comprises 50 annotated records stored on CD-ROM. >

An annotated database aimed at performance evaluation of algorithms for ST-T change analysis

Following the casual observation reported by one anginal patient of ours, of improvement of its claudicatio intermittens with application of isosorbide dinitrate ointment directly on the leg suffering pain, we undertook a study to assess the possible use of the drug in peripheral vascular disease in a group of 10 patients suffering of a severe form of claudicatio intermittens. The effect of the drug was tested 1) by the subjective valuation of the patient itself 2) by treadmill stress tests performed at constant rate. In this case were used as reference parameters the distance walked without any symptoms and the maximal distance reached by each patient. The treadmill stress test was performed in basal condition and after longterm administration of isosorbide dinitrate ointment 100 mg three times a day for 30-45 days. In 5 patients the control test was repeated twice in different days to evaluate the reproducibility of the measure that resulted good, while other 5 patients performed the test one hour following the application of the drug in order to assess a possible acute effect of the drug that was not present in any patient. All the patients noted an improvement in their walking capacity but only after 15-20 days of treatment. In basal condition the distance walked without any symptoms by the patients was on the average m. 51 (+/- 52) and the maximal distance reached was m. 143 (+/- 111), while after the treatment were m. 151 (+/- 136) and m. 384 (+/- 203) with a difference highly significative (p less than 0.05 and p less than 0.01 respectively). From our data although preliminary, it is apparent that longterm local application of isosorbide dinitrate is effective in the treatment of patients with peripheral vascular disease and that the action of the drug seems to be related to a local effect.

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Papers

Vasospastic ischemic mechanism of frequent asymptomatic transient ST-T changes during continuous electrocardiographic monitoring in selected unstable angina patients

The European ST-T database: development, distribution and use

Unreliability of conventional visual electrocardiographic monitoring for detection of transient ST segment changes in a coronary care unit.

An annotated database aimed at performance evaluation of algorithms for ST-T change analysis

[Intermittent claudication: topical treatment with isosorbide dinitrate ointment. Preliminary results].