This tool calculates the ventricular depolarization time from ECG measurements. The QRS duration represents the time it takes for the electrical impulse to travel through the ventricles.
Total QRS Duration (ms):
0 ms
Total QRS Duration (seconds):
0 s
Interpretation:
The duration is calculated as the product of the number of small boxes spanning the QRS complex and the time value of a single box, which is determined by the paper speed of the ECG recording.
Duration (ms) = (Boxes × 1000) / Paper Speed
For an ECG recorded at 25 mm/s showing a QRS complex width of 2.5 small boxes:
A normal QRS duration in adults is typically between 70ms and 100ms. Values above 120ms often indicate a bundle branch block or other intraventricular conduction delays.
Faster paper speeds (e.g., 50 mm/s) stretch the waveform. On these recordings, each small box represents 20ms of time, rather than the 40ms represented at standard 25 mm/s speed.
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