Use of a microprocessor-based pacemaker to control an implantable drug delivery system

Present strategies for treating paroxysmal atrial fibrillation are centered on the use of prophylactic oral administration of antiarrhythmic agents to prevent onset. This laboratory had proposed a system which senses the onset of atrial fibrillation and then delivers drug from an implanted pump to terminate infusion. In this system, arrhythmia detection was based on simple beat counting, while infusion was done with a programmable infusion pump. The viability of this system as an alternative to conventional therapy can be increased with a robust rate estimate based on median filtered AA interval measurements. System performance can be further enhanced by allowing on-line computation of appropriate drug delivery times. An optimal infusion based on patient pharmacokinetic parameters is capable of quickly reaching, then maintaining, therapeutic plasma levels. Design of this infusion requires solving the two-compartment pharmacokinetic equations. Since present pacing devices are incapable of floating-point operations, the two-compartment equations are solved indirectly using integer arithmetic, on/off control, and appropriate approximations