Two patients with ventricular premature beats.

Figure A shows that heart rate is 71 bpm, 2-beat scanning is adopted, and acquisition is at 30–80% of R-R interval. A premature beat is encountered at the second beat during scanning. The scanning does not stop, and continuously scans the next R-R interval. Figure C shows the heart rate to be 55 bpm, 1-beat scanning is adopted, and acquisition at is 70–80% of R-R interval. Scanning is stopped immediately when a premature beat in encountered, and the scan is resumed at the next normal cardiac cycle. Figures B and D show the ECG-edit of A and C respectively.