What do Q waves on ECG mean?

INTRODUCTION. 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 waves in inferior leads mean?

Q waves in the inferior leads present the picture of myocardial infarction of the lower, or frequently posterior, possibly laterally left ventricular wall.

What causes abnormal Q waves?

Background: Abnormal Q waves (AQW) in the electrocardiogram are commonly ascribed to underlying myocardial infarction (MI). As an imperfectly specific sign of MI, the usefulness of AQW in identifying MI depends on its incidence in the population studied.

Is Q wave in lead 3 normal?

Not all Q waves are indicators of MI. For example, a Q wave is normally seen in lead aVR. Furthermore, small “septal” q waves are normally seen in the left chest leads (I, aVL, and V4 to V6) and may be normal variants in one or more of leads II, III, and aVF.

How long do Q waves take to develop?

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. The presence of pathological Q waves, however, does not necessarily indicate a completed infarct.

Do Q waves always mean MI?

The presence of pathologic Q waves on ECG is not always associated with the presence of prior myocardial infarction on cardiac MRI. In addition, Q waves appear to modestly correlate with the location of the prior MI.

What does abnormal Q wave mean?

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.

Where is the Q wave?

The Q wave is the first downward deflection after the P wave and the first element in the QRS complex. 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.

What does an abnormal Q wave indicate?

What does abnormal inferior Q waves mean?

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.

How long does it take Q waves to 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.

Are Q waves ever normal?

QRS. The Q wave is a small negative deflection that precedes the R wave. 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.

Are there small Q waves in lead III?

Small Q waves and inverted T waves in lead III often disappear on deep inspiration. Occasional septal Q waves can be seen in other leads. ST elevation following an S wave (“high take off”) is common in leads V2–V4 and is quite normal.

How big is a Q wave in litfl?

1 Small Q waves are normal in most leads 2 Deeper Q waves (>2 mm) may be seen in leads III and aVR as a normal variant 3 Under normal circumstances, Q waves are not seen in the right-sided leads (V1-3)

Are there Q waves in the heart ECG?

They are usually absent from most leads of the ECG, but small Q waves are normal in the leads that observe the heart from the left; Q waves are sometimes seen in lead III, but disappear on deep inspiration. Q waves in leads other than the above can be considered pathological, particularly if they are:

What kind of Q wave is in AVL?

Individuals with electrical axis 60–90° often display a small q-wave in aVL. Leads V5–V6 often display a small q-wave (called septal q-wave, explained in this article). An isolated QS complex is allowed in lead V1 (due to missing r-wave or misplaced electrode).