[Artificial bradycardias due to tape-running problems of old long-term ECG records].
Artificial bradycardias due to tape-running alterations of old long-term ECG recorders were observed with increasing frequency in the last 2 years at our hospital. To document the extent of this problem, 115 consecutive 24-hour long-term ECG recordings of 10 still used tape recorders with an age of 12 +/- 4 years were examined. Analysis of the tapes with a new analysis system revealed artificial bradycardias with rates of 10 to 40/min in 22 of 115 long-term ECG recordings (19%). These artificial bradycardias were observed in 4 out of 10 examined tape recorders (40%). Three of 4 concerned recorders were 14 years old at the time of examination, and one recorder was only 5 years old. Artificial bradycardias were caused by extensive alterations of tape-running speed in all cases. Diagnostic proof of artificial bradycardias due to tape running alterations on long-term ECG are simultaneous with prolonged RR-intervals occurring increases in all ECG times including P-width. PQ-time, QRS-width and QT-duration with otherwise unchanged ECG morphology. To avoid prolonged hospital stays or therapeutic mistakes like unnecessary pacemaker implantation, especially older long-term ECG-tape recorders should be checked regularly and, if necessary, be replaced by new devices.