Increased need for smaller, cheaper and more readily available ECG equipment worldwide drives integration within this patient focused space. Silicon integration can easily capture obvious functional blocks condensing amplifiers, converters and switches with relative ease. Inclusion of appropriate digital post processing capabilities on chip delivers a solution centred outcome targeted at enhancing overall offering, shortening end user design cycles, as well as increased value add. With the numerous challenges facing designers to satisfy functional, performance, program and regulatory demands, solutions designed with a emphasis on simplifying end system challenges provide a welcome head start.
Patient monitors, whether in or out of hospital will deliver on a particular feature-set suited to their end use application, such as channel count, types of measurement such as thoracic impedance measurement, pace maker detection, SpO2, or temperature to name a few. In addition to such features, systems get distinguished by performance requirements such as diagnostic or monitor requirements and form factor restrictions to ensure patient comfort all come into the mix.
When heart patients with implanted pacemakers undergo electrocardiogram (ECG) testing, a cardiologist must be able to detect the presence and effects of the pacemaker. The electrical signature of the pacing signal consists of small, narrow pulses. Buried in noise and larger cardiac signals, these artifacts can be difficult to detect.
With almost half a million pacemakers implanted worldwide each year, these ECG instruments must be capable of identifying and distinguishing a pacemaker signal or artifact from the ECG capture. Some equipment will have this implemented using a hardware detection circuit while others will use their own post processing in the digital domain.
In this article, John Kruse and I describe the variety of different pacemakers in use, the nature of the pace pulses and introduce the ADAS1000 integrated ECG front end with on-chip digital pace detection algorithm which runs simultaneously to the ECG measurements. There are three instances of the digital algorithm enabling detection of pace artifacts on 3 leads, the algorithm has some programmable thresholds to assist users capture the defined range of pacer signals under different conditions.