As a medical professional with expertise in cardiology, I can provide insight into the presence of Q waves on an electrocardiogram (ECG). Q waves are typically associated with myocardial infarction (heart attack) or other conditions that cause damage to the heart muscle. However, in some cases, Q waves can be a normal variant, particularly if they are small and meet specific criteria. Normal Variant Q Waves are generally less than 0.04 seconds in duration and do not exceed one-third the depth of the subsequent R wave in leads where they are present. They can be seen in leads III, aVR, and V1-V3, and are often a normal finding in young individuals and athletes. It's important to note that the interpretation of Q waves in an ECG should be made in the context of the patient's history, symptoms, and other ECG findings. A single Q wave meeting the criteria for a normal variant does not necessarily indicate a problem, but multiple Q waves or Q waves that are not meeting the criteria for a normal variant should prompt further investigation for possible heart disease. read more >>

When the first deflection of the QRS complex is upright, then no Q wave is present. The normal individual will have a small Q wave in many, but not all, ECG leads. Abnormalities of the Q waves are mostly indicative of myocardial infarction and discussed further inside the relevant sections of ECG Reviews and Criteria.read more >>