What is resting height of QRS deflection?

The resting height of the QRS deflection, also known as the baseline or isoelectric line, refers to the level of the electrocardiogram (ECG) trace when no electrical activity is occurring in the heart. It serves as a reference point for measuring the amplitude of the QRS complex, which represents ventricular depolarization. Ideally, the QRS complex should rise above this baseline during a normal heartbeat, indicating proper electrical conduction through the ventricles. Any significant deviation from this resting height can indicate underlying cardiac issues.