ARRHYTHMIA RECOGNITION STRATEGIES AND HARDWARE DECISIONS FOR THE IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR - A REVIEW

The avoidance of inappropriate shocks from the implantable cardioverte r-defibrillator (ICD), together with its need to apply antiachycardia pacing to either atria or ventricles, demands considerable sophisticat ion in the design of algorithms to interpret electrical or other cardi ac signals in real-time, Methods based on rate and using single short- gap bipolar leads lack discrimination. Right ventricular electrogram m orphology algorithms offer improvement but no universal algorithm exis ts; however, for any given patient an optimum algorithm of this type m ight be found. One improvement would be to provide atrial information in addition, by employing more than one electrode or a long-gap single bipolar lead. Alternatives transducer signals could be included, once their efficacy and reliability have been improved. A different approa ch would be to use the much more sophisticated algorithms at present b eing tried with surface electrocardiograms. Integrated Circuit technol ogy is reaching the point where this could be done but the requirement for exceptionally high reliability means that special system structur es, such as a Memory intensive Computer Architecture, may be required. When decisions on these approaches are to be made, it must also be re membered that ICDs will soon be implanted and programmed as a routine rather than highly specialized procedure.