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Patient
63-year-old man with dilated cardiomyopathy referred to the cardiologist due to ’abnormal’ electrocardiogram;
Trace
Sinus rhythm with a clearly visible P-wave in lead II (slightly less distinctive in V5, V6); there is marked movement of the baseline which could be misdiagnosed as atrial arrhythmia; left bundle branch block;
Patient
Young female patient 23 years of age with no cardiac history;
Trace
Sinus rhythm with a clearly visible P-wave in lead III; the remainder of the tracing is extremely contaminated with rapid and chaotic waves superimposed over the normal tracing; this tracing is thus very difficult to interpret;
Trace
This tracing was recorded a few minutes after the first recording, the patient is now in a more comfortable position resulting in a tracing of much higher quality; normal pattern;
Exergue
The presence of baseline undulation or significant noise artifact in the tracing renders any interpretation perilous and can lead to misdiagnosis (arrhythmias, coronary syndrome with STEMI, etc.)
Comments
Tracing recorded a few minutes later with careful re-application of the electrodes; disappearance of the baseline movements; tracing is now of much better quality and thus interpretable; confirmation that the rhythm is indeed sinus rhythm;
A perfect recording quality is a necessary prerequisite for the correct interpretation of an ECG; it is therefore imperative to obtain a tracing with good definition of all 12 leads without noise or artifacts.
The quality of the recorded tracing can be altered for a number of reasons: