Development of a Pacemaker Test System Using LabVIEW, Biomedical Toolkit, and PXI

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"We designed a software validation and verification process for medical devices by developing the Pacemaker Test System and developed a software validation system of many medical devices."

- Park Jong-Dea, System Integration Dept. Ltd. INNOTEMS

The Challenge:
To develop a high-precision medical device pacemaker, we had to develop a system that can be tested with the pacemaker. Testing the medical device is difficult and complex because of the equipment required to develop a test system and the process of outputting the result.

The Solution:
The pacemaker test system performs processes like medical device software validation and verification of equipment operation using a pacemaker simulator system. The system simulates the output pacemaker pacing simulated signal, and is configured to measure the biosignal test and the performance of the original pacemaker.

Author(s):
Park Jong-Dea - System Integration Dept. Ltd. INNOTEMS

Ltd. INNOTEMS

INNOTEMS has expertise and knowledge in PC-based control and instrumentation R&D, system inspection and testing, system consulting, automobile, machinery, aviation, aerospace, medical, and education. The company uses system integration services based on LabVIEW software.

Figure 1. The Test Structure

Cardiac

The human heart, which is about the size of a fist, pumps about 5 liters of oxygen-rich blood and nutrients per minute to each part of the body.  A normal heart generates a pulse of approximately 60 to 100 beats per minute. A cardio workout creates a muscular ventricular conduction of electrical stimulation in the sinus node of the conduction system in the heart.

Figure 2.

Pacemaker

When the beating of the heart is abnormal (too fast or too slow) or irregular, a device can keep the heart rate normal through periodic electrical stimulation to the heart. Different types of pacemakers include body catering, body embedded, or inductive.

A pacemaker is composed of a heart rate generator and an electrode lead. The heart rate generator may contain the electronic circuit and the battery to control the electrical stimulation at regular intervals. The electrode lead is an electric signal generated in the pacemaker that passes to the heart.

Figure 3.

The Configuration of the Pacemaker Simulator System

May perform the functions of the pacemaker. The software can simulate a variety of biological signals in a built-in small PC, which outputs a biological signal analog output channel, and measures a feedback signal analog input channel. In addition, it shows the operating status of the heart more easily on the human dummy to install adequate lighting for enhanced visibility.

For simulation of various heart movements, each cardiac outputs a signal.

  • Arrhythmia—The rhythm of the heart rate is irregular status.
  • Bradycardia—The heart rate is beating slower than normal.
  • Tachycardia—The heart rate is beating faster than normal.

Heart rate is measured through analysis of the cardiac signal.

Figure 4.

The Configuration of the Pacemaker Test System

Display the electrocardiogram that occurs in the heart. Pacing threshold, refractory period, heart rate, and coordinated pacing can set the escape interval and impedance.

Data logging so that data can be stored on any heartbeat. This feature has been added. And selecting the type of pacemaker like  AAI, VVI, and DDD is possible.

  • AAI: Paces and senses in the atrial.
  • VVI: Paces and senses in the ventricle. A sensed beat inhibits the pacing stimulus (demand pacing).
  • DDD: Paces and senses in both chambers. A sensed beat in the ventricle inhibits both the ventricular and atrial pacing stimulus and triggers a ventricular pacing stimulus after a programmed AV interval.

Figure 5.

Pacemaker Function Tests

Inspection of the pacemaker. Except for lead and electrode, inspection items are processed by the Pacemaker Performance Evaluation Manual.

Inspection items

  • Amplitude, pulse, length, rate, interval of pulse
  • Sensitivity
  • Input impedance
  • Intervals
  • Detection refractory period, beating refractory period
  • AV intervals

Inspection items are required for each set and hardware.

The case of the amplitude, length, rate, intervals in pulse.

  • Measuring equipment components: Scope module (input impedance> 1MΩ), noninductive resistor (240Ω, 500Ω, 1KΩ ± 1%)
  • Criteria: within ± 5% of the reference value or, within the manufacturer’s tolerances.
  • Inspection configuration.

Figure 6.

 

The software configuration of the pacemaker test system was built with TestStand, and each test sequence was constructed by function.

Detailed unit test software was written with LabVIEW, and inspection items and the inspection method were carried out according to standards such as IEC 62304 and ISO 14971.

Conclusion

It is difficult to examine it since the pacemaker is inserted into a human body and has a variety of functions. In terms of using TestStand, you can conduct inspections rapidly and simply by making it possible to examine them in the form of the sequence structure.

Once the inspection is complete, the results and the related document are printed out. It helps you to manage them easily.

We designed a software validation and verification process for medical devices by developing the Pacemaker Test System and developed a software validation system of many medical devices.

Author Information:
Park Jong-Dea
System Integration Dept. Ltd. INNOTEMS
South Korea
Tel: 010-5160-0615
jdpark@innotems.com

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