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Electrocardiographs (ECG) units are used to measure signals produced by the heart. Some newer models have the ability to analyze these signals and provide a detailed reports of the readings.

This accuracy of the information provided by these units is best maintained by performing yearly preventative maintenance as well as regular checks for any physical damage to the unit. The preventative maintenance of ECGs includes accuracy testing, electrical safety analysis and functionality testing of any additional components.

During accuracy testing the unit is examined at multiple different heart rates. This is tested with a patient simulator and the unit is tested within a range of 30 and 240 beats per minute (BPM). During this time any alarms are also tested such as heart rates outside of the normal range. Testing the accuracy is recommended for many of these units however specific ranges are not always outlined. For example the Philips page writers 100, 200 and 300 reference this testing but do not outline the rates [1]. That is why TRH services chooses to test over a wide range so that any failures of accuracy can be found and resolved.

Electrical safety analysis ensures that the unit is properly grounded and has normal leakage current [1]. ECGs have the additional electrical safety test of ensuring the leads for the unit are isolated from each other and will prevent current from passing between them [1]. During this time the leads are examined for any signs of damage such as exposed wire or artifacts present on the leads [1]. Any damage to the leads can affect the accuracy of the unit. It is recommended to check the leads regularly for any damage that could cause noise within the signal [1]. It is also important to ensure the units electrodes are in good condition before use as this is another aspect that can affect the accuracy of the unit.

Additional components can include displays, keypads, and printers. Displays and keypads are examined for any physical damage and functionality [1]. Further testing including self tests and calibration, are tested as outlined by the manufacturer [1]. Printers are present on most units, a set of readings are printed during the annual maintenance to ensure the printing can be read and that the settings are correct. This is also when internal sensors are tested such to ensure functionality such as the low paper sensor. This issue can be seen with the Philips page writer 100, 200 and 300 units that require a hole in the paper to be sensed when printing on the automatic setting [1].

As with most medical equipment, it is recommended to ensure the battery is properly maintained. This includes replacing the battery as recommended and keeping the unit plugged in to prevent it from depleting [1].

There areĀ  a few common issues that occur with these units. An error that can be seen more frequently is incorrect settings due to changes in the number of leads. Many machines can support multiple varieties of leads such as 3, 5 and 10 lead cables. For example the ELI 280 unit made by Burdick allows for 3 and 12 lead variations [2]. If the machine is on the incorrect setting it may still read values but may not provide accurate information. It is important to note that if the unit does not sense that all leads are connected to the patient it may show an error code until all leads are properly connected. This error can be seen on the ELI 280 units as they will not read any values if all leads are not connected [2]. The misplacement of leads or improper connection of leads can also cause the unit to provide inaccurate information or error codes [2].

By ensuring that annual preventative maintenance is performed by a qualified technician many of these errors can be avoided. This maintenance should be done in addition to assessments which should be performed when the unit presents an unknown error code or its accuracy is questioned. All of the technicians at TRH services have experience regarding the maintenance and assessment process for a large variety of ECG units and are committed to ensuring that each unit is functioning as per their manufacturers standards.

Here is a brief list of some equipment that we work on:

Equipment Tested by TRH Services

Model Number
Burdick CorporationAtria 6100
Burdick CorporationEK10
Burdick CorporationELI 280
Edan Instruments Inc.ES-1200 Express
Edan Instruments Inc.SE-1200
GE Medical Systems Information Technologies Inc.MAC 2000
GE Medical Systems Information Technologies Inc.MAC1200
GE Medical Systems Information Technologies Inc.PDM
General Electric CompanyMAC 5000
General Electric CompanyMAC 5500
General Electric CompanyMAC 5500 HD
Global instrumentationM12R
Hewlett PackardM1772A
Mortara Instrument IncELI 150 Rx
Mortara Instrument IncELI 150c
Mortara Instrument IncELI 150Rx
Mortara Instrument IncELI 1XX Series 2
Nihon Kohden CorporatedECG-1250A
Norav Medical Ltd1200M
Northeast Monitoring IncDR180+
Philips Healthcare860315 (PageWriter)
Philips HealthcareM1770A
Philips HealthcarePagewriter Trim III ABA A03
Philips Healthcare860315
Philips Healthcare860284
Philips Medical SystemsPage Writer Trim III
Pulse Biomedical Inc.QRS Card USB
QRS DiagnosticUniversal ECG
Schiller AGAT-1
Schiller AGCardiovit AT-2
Welch AllynAT-2
Welch AllynSE-PRO-600
Welch AllynCP2A
Welch AllynCP200
Welch AllynCP150
Welch AllynCP100
Welch AllynCP 200
Welch AllynCOMPUTER SE-PRO-600
Welch AllynCP 100




Page 61

  1. PageWriter 100, 200 and 300 series Cardiographs M1170A, M1771A, and M1772A, Mobile Cart M1705B Service Manual, 3rd Hewlett-Packard Company. USA, 1998. Chapter 2: Performance and Verification.
  2. ELI 280 User Manual, Rev C. Mortara Instrument Inc. Wisconsin, USA, 2018


Written by: Dixon Murphy
Edited by: Tyler Hasenpflug CET