What does an R wave represent?

As a domain expert in cardiology with a focus on electrophysiology, I can explain the significance of the R wave in an ECG reading. The R wave is a critical component of the ECG waveform, representing the initial and primary phase of ventricular depolarization. This phase is when the ventricles of the heart begin to contract, which is a crucial step in the heart's pumping action. The R wave is typically the most prominent feature of the ECG and can be easily identified following the P wave. It is particularly noticeable because it reflects the synchronized contraction of the ventricular muscle. In a standard ECG, the R wave is expected to be present and is often used as a reference point for interpreting other features of the ECG. The size and shape of the R wave can vary based on several factors. For instance, an enlarged R wave can be indicative of conditions such as ventricular hypertrophy, where the heart muscle has thickened, or it may be seen in individuals with a thin chest wall or those who are physically fit due to the closer proximity of the heart to the chest wall, which allows for a stronger signal to be recorded on the ECG. It's important to note that while the R wave is a normal part of the ECG, any abnormalities in its appearance should be evaluated by a healthcare professional to determine if there are any underlying cardiac conditions.

The R wave is the first upward deflection after the P wave (even when Q waves are absent). The R wave is normally the easiest waveform to identify on the ECG and represents early ventricular depolarisation. The R wave may be enlarged with ventricular hypertrophy, a thin chest wall or with an athletic physique.