The Q wave is typically a small negative deflection seen in an electrocardiogram (ECG) recording. It represents the depolarization of the interventricular septum, which is the wall between the left and right ventricles of the heart. The Q wave is usually followed by the R wave, which is a large positive deflection.
The negative deflection of the Q wave is due to the direction of electrical depolarization in the heart. When the electrical impulse moves from the left ventricle towards the positive electrode on the skin, it creates a positive deflection (R wave) because the movement is towards the electrode. However, when the impulse moves away from the positive electrode, as it does during the initial depolarization of the interventricular septum, it creates a negative deflection (Q wave) on the ECG.
It's important to note that the presence or absence of a Q wave, as well as its size and shape, can provide valuable diagnostic information for various cardiac conditions. Changes in the Q wave can indicate myocardial infarction (heart attack), ventricular hypertrophy, conduction abnormalities, or other cardiac abnormalities. Therefore, it's essential to consider the clinical context and consult a healthcare professional for an accurate interpretation of ECG findings.