What do Q waves on ECG mean?
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.
Why is there Q wave in myocardial infarction?
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.
What does it indicate if the Q wave is missing?
The absence or particularly recent loss of septal q waves may be a sign of septal infarction, various forms of conduction defects, fibrosis of the middle third of the ventricular septum and proximal left anterior descending coronary disease, especially when combined with other electrocardiographic evidence of …
Why is Q wave negative in ECG?
As septal depolarization moves from left to right, the depolarization vector is directed towards the – electrode of lead II (RA), and therefore a negative-going deflection (Q-wave) is produced.
What is a transmural Q wave infarction?
A transmural myocardial infarction refers to a myocardial infarction that involves the full thickness of the myocardium. It was one believed that the development of Q waves indicated the infarction was “transmural;” however, autopsy studies failed to confirm this.
What would be expected when evaluating an ECG for an inferior infarction?
Upon ECG analysis, inferior STEMI displays ST-elevation in leads II, III, and aVF. There are subtle differences in the ECG pattern depending on the artery occluded. Reciprocal changes (ST-segment depression) may be seen in lead aVL .
What is the significance of the Q wave in myocardial infarction?
Significance of the Q wave in acute myocardial infarction Acute myocardial infarction may be associated with the development of Q waves on the electrocardiogram (ECG), or with changes limited to the ST segment or T wave. The ECG changes do not accurately differentiate transmural from nontransmural infarction.
What is a Pathological Q wave in ECG?
Pathological Q-waves are evidence of myocardial infarction. Myocardial infarction – particularly if extensive in size – typically manifests with pathological Q-waves. These Q-waves are wider and deeper than normally occurring Q-waves, and they are referred to as pathological Q-waves.
Should we evolve ECG evidence of Q-wave infarction?
The AHA’s 2013 STEMI guideline states that “the majority of patients will evolve ECG evidence of Q-wave infarction,” and the 2014 NSTEMI guidelines state that “significant Q-waves are less helpful…suggesting prior MI.” [2-3]
Do Q-waves on the ECG mean myocardial necrosis?
The 2017 ESC guideline now states that “the presence of Q-wave on the ECG should not necessarily change the reperfusion strategy, and the 2018 Fourth Universal Definition of MI explains that “in general, the development of Q-waves indicates myocardial necrosis, which starts minutes/hours after the myocardial insult.