Assessing the diagnostic functionality of electrocardiographs currently used in Helsinki hospitals.
To assess the diagnostic quality of current electrocardiography in Helsinki hospitals, 156 devices (95 percent from one manufacturer) were tested for performance by means of 11 test parameters. To analyze the devices as a system, a figure of merit (FM) was calculated for each device. Seventy-nine percent of the devices passed the tests. The device failure rate increased after the age of five years, and most of the failed devices exceeded 10 years of age. The most important device error was a false ST-segment depression caused by the electrocardiographs themselves. This was revealed by using a triangle pulse to the low-frequency response. This method should be included in international standards. On the basis of economics, the life cycle of an ECG should always exceed six years. However, extending the life cycle beyond five years reduces device reliability. Service costs were found to be insignificant in comparison to capital costs unless the life cycle is beyond 10 years. The results indicate that the present problem in maintenance in Helsinki hospitals is to provide and organize preventive maintenance so as to find the devices in need of service. The costs of preventive maintenance are a small price to pay to ensure the diagnostic accuracy of electrocardiographs. The FM and methods of testing described here may be useful in other areas and in other ECG evaluation programs.