The "RS" in an ECG (Electrocardiogram) refers to the combination of the R-wave (a positive deflection) and the subsequent S-wave (a negative deflection) that follows it within a QRS complex.
Understanding the ECG Components
To understand the RS complex, let's break down the relevant components of an ECG:
- P-wave: Represents atrial depolarization (contraction).
- QRS complex: Represents ventricular depolarization (contraction). This is the most prominent feature on an ECG.
- T-wave: Represents ventricular repolarization (relaxation).
The R and S Waves
- R-wave: The first positive (upward) deflection after the P-wave within the QRS complex. If there is no initial negative deflection (Q wave), the first positive deflection is the R wave. If there are multiple positive deflections, they are labeled R', R'', etc.
- S-wave: A negative (downward) deflection following an R-wave within the QRS complex. It represents the final phase of ventricular depolarization.
The Significance of the RS Complex
The shape, amplitude, and duration of the QRS complex, including the R and S waves, provide valuable information about:
- Ventricular function: Abnormalities can indicate issues like ventricular hypertrophy (enlargement) or conduction blocks.
- Myocardial infarction (heart attack): Changes in the QRS complex can indicate previous or ongoing heart damage.
- Arrhythmias: Irregular heart rhythms can affect the appearance of the QRS complex.
- Electrolyte imbalances: Conditions like hyperkalemia (high potassium) can alter the QRS complex.
Example
Imagine an ECG tracing. After the P-wave, you see a sharp upward spike (the R-wave), immediately followed by a downward dip (the S-wave). The combination of these two deflections is the RS complex.
