Technician produces recordings of electromotive variations in patient's heart muscle, using electrocardiograph (ECG), to provide data for diagnosis of heart ailments: Attaches electrodes to chest, arms, and legs of patient. Connects electrode leads to electrocardiograph and starts machine. Moves electrodes along specified area of chest to produce electrocardiogram that records electromotive variations occurring in different areas of heart muscle. Monitors electrocardiogram for abnormal patterns. Keys information into machine or marks tracing to indicate positions of chest electrodes. Replenishes supply of paper and ink in machine and reports malfunctions. Edits and forwards final test results to attending physician for analysis and interpretation. May attach electrodes of Holter monitor (electrocardiograph) to patient to record data over extended period of time.