What does the vertical line on an ECG strip represent?

The vertical line on an ECG strip represents voltage or amplitude. In an electrocardiogram, the vertical axis shows the electrical activity of the heart, quantified in millivolts (mV). This indicates how much electrical charge is present at various points in time during the cardiac cycle. The greater the upward deflection from the baseline, the stronger the electrical activity in that region of the myocardium, which can help healthcare professionals assess the heart's function and detect abnormalities such as ischemia or hypertrophy.

Understanding this aspect of an ECG is crucial for analyzing the heart's electrical conduction and interpreting the overall health and function of the cardiac system.