What constitutes a pathological Q wave?
Pathologic Q waves are a sign of previous myocardial infarction. They are the result of absence of electrical activity. A myocardial infarction can be thought of as an elecrical ‘hole’ as scar tissue is electrically dead and therefore results in pathologic Q waves.
Which leads are pathologic Q waves?
Small Q waves (<0.03 seconds in duration) are a normal finding in all leads except V1 through V3, where they are always pathologic. Q waves of any size may be normal in leads III and aVR. Pathologic Q waves are indicative of transmural myocardial infarction (see Chapter 18).
What do Q waves on ECG mean?
By definition, a Q wave on the electrocardiogram (ECG) is an initially negative deflection of the QRS complex. Technically, a Q wave indicates that the net direction of early ventricular depolarization (QRS) electrical forces projects toward the negative pole of the lead axis in question.
What does Q represent on ECG?
Electrocardiogram Interpretation Q waves represent the initial phase of ventricular depolarization. They are pathologic if they are abnormally wide (>0.2 second) or abnormally deep (>5 mm). Q waves that are pathologically deep but not wide are often indicators of ventricular hypertrophy.
When do pathological Q waves develop?
Pathological Q waves Q waves may develop within one to two hours of the onset of symptoms of acute myocardial infarction, though often they take 12 hours and occasionally up to 24 hours to appear.
What do Q waves indicate?
Technically, a Q wave indicates that the net direction of early ventricular depolarization (QRS) electrical forces projects toward the negative pole of the lead axis in question. Although prominent Q waves are a characteristic finding in myocardial infarction, they can also be seen in a number of noninfarct settings.
What are abnormal inferior Q waves?
Conclusion: Abnormal Q waves on the admission electrocardiogram (ECG) are associated with higher peak creatine kinase, higher prevalence of heart failure, and increased mortality in patients with anterior MI. Abnormal Q waves on the admission ECG of patients with inferior MI are not associated with adverse prognosis.