Ann Arbor Electrogram Libraries

About Us

Ann Arbor Electrogram Libraries was started in the Medical Computing Laboratory at the University of Michigan in Ann Arbor, where over a time span of fifteen years, hundreds of recordings of EP sessions were recorded, annotated and digitized for arrhythmia algorithm development.

Hundreds of academic papers were published, more than a dozen patents were granted and students who performed graduate-level work on these recordings in the medical computing laboratory graduated to positions at the top cardiac management companies in the world.

These electrogram libraries were made available for both business and academic use through a licensing agreement, and copies of these digitized and annotated electrograms can be found in every major cardiac rhythm management and implantable defibrillator manufacturer in the world.

Electrogram Libraries recordings are considered the "reference standard" against which new algorithms must be tested. The US Food and Drug Administration was one of the first organizations to license this data.

Industry Standard Practices

The industry standard Ann Arbor Electrogram Libraries provides benchmark wideband unipolar and bipolar intracardiac electrograms of cardiac arrhythmias for scientific investigation. These recordings allow scientists and ICD developers alike to utilize identical data for testing and device design. Each recording consists of surface electrocardiograms (ECGs) and intracardiac bipolar and unipolar electrograms of diverse cardiac arrhythmias. All recordings have been made during routine cardiac electrophysiology studies at the Michigan Heart & Vascular Institute. Each recording has been annotated and reviewed by a cardiac electrophysiologist and an electrical engineer to ensure an accurate interpretation of each arrhythmia and consistent quality with regard to recording of the electrograms. Patient demographics and antiarrhythmic agents, when utilized, are included in the annotation of each recording.

Data Acquisition

Electrograms were recorded during routine clinical studies in the cardiac electrophysiology laboratory. Patients were studied in a supine position and in a fasting, postabsorptive state. After sedation with 1-3 mg of intravenous medazolam and administration of 1% lidocaine for local anesthetic, one 8 French and two 6 French side-arm sheaths (Cordis Corp., Miami, FL, USA) were positioned in the right femoral vein using the Seldinger technique. Each patient received 50 units/kg of heparin intravenously as a bolus. Three 6 French quadrapolar electrode catheters (USCI Division, C.R. Bard Inc., Billerica, MA, USA) with an interelectrode distance of 1 cm were introduced and advanced under flouroscopic guidance. Each electrode catheter had 3 platinum ring electrodes which were cylinders 2 mm in diameter and 2 mm in length. The platinum tip electrode of each catheter consisted of a half-sphere 2 mm in diameter attached to a cylinder 2 mm in diameter and 1 mm in length. The resulting surface area of each ring and tip electrode was 12.6 mm. One electrode catheter was positioned in the high right atrium or right atrial appendage. Two electrode catheters were positioned in the right ventricular apex for right ventricular apex pacing and recording, respectively. Unipolar electrograms were recorded using the distal right ventricular apex electrode as the exploring electrode with a heparinized 0.9-mm guidewire (Cordis Corp., Miami, FL, USA) inserted into the 8 French venous sidearm sheath serving as the indifferent electrode. The guidewire was positioned in the right femoral vein extending into the right iliac and distal 5 cm of the inferior vena cava. At the end of each procedure, the guidewire and sheath were carefully examined and the absence of thrombus formation was confirmed. In addition to intracardiac atrial and ventricular electrograms, two or three electrocardiographic surface leads (V1, I, III) were also recorded continuously during the study. Sustained monomorphic ventricular tachycardia and sustained ventricular fibrillation were induced by programmed ventricular stimulation or alternating current.

Twelve lead electrocardiograms were recorded during spontaneous baseline rhythm and subsequently induced monomorphic ventricular tachycardia and ventricular fibrillation after positioning of the recording electrode catheters in the appropriate chambers. Distal unipolar and bipolar intraventricular electrograms were recorded continuously on FM magnetic tape at a tape speed of 3.75 in. (9.5 cm)/sec (Hewlett-Packard Model 3968A, San Diego, CA, USA) after signal amplification at 1--500 Hz . Amplifier gain and filter settings were held constant during the entire recording procedure, and a 1 mV calibration signal was entered as a reference at the time of recording.

Numbering Convention

Each Ann Arbor Electrogram Libraries (AAEL) recording has been assigned a number (such as AAEL001). In instances where a recording represents more than one patient, the AAEL number is followed by a dash and a second number (for example, AAEL239-1). If a patient's recordings include intentional changes in intracardiac lead positions, the AAEL number is followed by a letter (for example, AAEL 239A, AAEL 239B).

Arrhythmia Definitions

Single atrial premature depolarizations (APDs) and ventricular premature depolarizations (VPDs) during sinus rhythm have been quantified. Two or more consecutive APDs are referred to as repetitive APDs (RAPDs). Two or more consecutive VPDs are referred to as repetitive VPDs (RVPDs). Any supraventricular tachycardia or ventricular tachycardia having a duration of 6 or more cycles has been annotated separately. Atrial fibrillation is diagnosed if the atrial rate is greater than 330 cycles per minute. Atrial flutter is diagnosed if the atrial rate is 240-330 cycles per minute. Supraventricular tachycardia is diagnosed if the atrial rate is between 140 and 240 cycles per minute, and its conduction pattern (1:1, 2:1, 3:1, etc.) is reported. Monomorphic ventricular tachycardia (VT) is defined as ventricular tachycardia having a monomorphic configuration and a cycle length of 500 or less milliseconds. Polymorphic ventricular tachycardia (PMVT) us defined as a ventricular tachycardia having a polymorphic configuration and cycle length of 500 or less milliseconds. Ventricular flutter (VFt) is defined as any monomorphic VT with a consistent cycle length of 250 or less milliseconds. Ventricular fibrillation (VFb) is defined as any PMVT with a consistent cycle length of 250 or less milliseconds.

Publication Requirements

The use of Ann Arbor Electrogram Libraries recordings should be cited and data acquisition procedures should be included in the Methods section of any published paper as follows: [ Electrogram Libraries, Chicago, IL USA]. The number of each Ann Arbor Electrogram Libraries recording utilized must be cited specifically in any tabular listing of results. This requirement is mandated in order to make possible a comparison of the results of any published paper with those of previous as well as future studies which also utilize the Ann Arbor Electrogram Libraries.


The Ann Arbor Electrogram Libraries is a compilation of hundreds of recordings which span more than a decade. This library represents the work of a team of professionals who have dedicated extensive hours to the collection, organization, annotation, and preparation of this database for use by authorized licensees only. Copying of this scientific data and unauthorized distribution is expressly prohibited.