Before revision:  The boundaries of the ECG signal complexes are manually annotated by cardiologists for all samples and independently for each lead . The database is representative of a variety of signal morphologies .
After revision:  The boundaries of the ECG signal complexes are manually annotated by cardiologists for all samples and independently for each lead , and all records received an expert classification by abnormalities. In addition, the database is representative of a variety of signal morphologies .