From Holter Monitors to Automatic Defibrillators: Developments in Ambulatory Arrhythmia Monitoring

In 1961, Holter reported a design of a tape recorder that acquired and stored electrocardiographic (ECG) signals from ambulatory patients. This made long-term monitoring of patients in their day-to-day environments possible. The next generation of devices employ microcomputer circuits for automatic interpretation of cardiac arrhythmias. Implantable pacemakers also show some arrhythmia interpretation capability. A special case is the automatic implantable defibrillator which recognizes the ventricular fibrillation signal. We present here the details of the original Holter recorder, the microcomputer-based arrhythmia monitor, and the automatic implantable defibrillator. In conjunction with the historic account of these developments, we present the current techniques of ambulatory ECG signal acquisition, processing, arrhythmia detection, and performance evaluation of automated arrhythmia detectors.