Implantable microprocessor-based devices for the management of arrhythmia

Microprocessors of small size and low power are being used in implantable devices for control of cardiac rhythm. The authors have developed two applications of this technology: (1) signal processing algorithms for accurate arrhythmia identification in an antitachycardia pacemaker or defibrillator and (2) control algorithms for pharmacokinetically based infusion of antiarrhythmic drugs from an implanted pump. For tachycardia identification they have used rate and regularity, amplitude-distribution histograms, Fourier spectra, and autocorrelation analysis of the atrial and ventricular electrograms. For automatic antiarrhythmic drug infusion, they have used procainamide and disopyramide in patients and animals and have studied the efficacy of these drugs for acute management of paroxysmal atrial fibrillation. In one dog they implanted a complete system which recognizes atrial fibrillation and automatically dispenses the drug from a subcutaneous reservoir