Manual Annotations

Manual annotations were made by two experts using a SUN workstation using WAVE[3]. The extraction of the annotation file which contains the QRS annotations was made automatically, generating the record.man annotation file. Each expert added estimated waveform boundaries to a copy of the record.man file. In this way we have for each record two manual annotation files denoted by record.qtn, where n=1,2 denotes expert who performed the annotations. A screen similar to that shown shown in Fig. 1 was presented to the expert annotators to support the editing process. Both leads were displayed simultaneously, and then a decision was made about the time location of the fiducial point. Fiducial points were marked by a `$\mid$' symbol, movable by a cursor, and the times were added to the annotation file. These annotations were audited to correct the inconsistencies detected (e.g., misplaced or missing annotations) and changed to the regular annotation symbols `(' ,`)', `t', `p', and `u', to produce the record.qnc files, containing the final manual annotations. For 11 records the procedure was repeated for a second annotator (n=2).

  

Figure 1: WAVE screen display as used by the expert annotators for marking the locations of wave boundaries. The software automatically stores the chosen locations, and moves ahead to the next beat to be marked.

  

Figure 2: Screen display of the record in Fig. 1 after the manual annotations have been completed.