: R-Wave Amplitude

: What R-Wave Amplitude Means

: The R wave is the tall upward spike seen on an ECG tracing. Its amplitude reflects the size of the electrical signal detected by the electrodes as the ventricles (the heart's lower chambers) activate. Because the recorded height depends on lead placement, body size, and electrode contact, it is assessed in context rather than in isolation.

: How It Is Measured

: R-wave amplitude is read directly from the ECG waveform, typically in millimeters or millivolts, on standardized ECG paper. It is not measured from a blood sample. Consistency in lead position and calibration helps ensure the reading can be compared over time.

: What Can Affect the Reading

: Amplitude can vary with electrode placement, skin contact, body habitus, and breathing. Certain heart conditions such as chamber enlargement or conduction changes can also alter the height of the R wave in particular leads. Technical factors are therefore considered before attributing changes to disease.

: How Results Are Used

: Clinicians interpret R-wave amplitude together with the full ECG, including other waveforms, intervals, and the patient's symptoms and history. It may contribute to assessing conditions like ventricular enlargement, but it is not diagnostic on its own.