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Pathological q waves ecg11/6/2023 ![]() An electrocardiographic and vectorcardiographic analysis. Q waves are considered pathological if: > 40 ms (1 mm) wide. The effect of respiration on normal and abnormal Q waves. Determination of lead III Q waves significance. Diagnostic value of Q-waves in inferior myocardial infarction. Shettiga UR, Hultgrenm HN, Pfeifer J, Lipton MJ (1974). Such Q waves may be more representative of normal anatomic variation than actual pathology while pathologic Q waves may be accompanied by repolarization. ![]() I’m happy to be corrected though! If there is not a pathological Q wave in aVF (>25% of the R wave amplitude), then a Q wave in lead III can be ignored.ġ. I know this is standard practice in some departments but several studies back in the 1970s (1,2,3) failed to find any benefit in this manoeuvre and as far as I know there are no authoritative recommendations for it. One thing I disagree with Scott about is the usefulness of recording lead III on deep inspiration to determine whether or not the Q wave is pathological. I must confess that this is beyond my level of knowledge – do any of SCST’s EP/arrhythmia experts have any comments to offer on this theory? Scott suggests that the ectopic runs may be reentrant in nature, initiated by the 1st VPB and involving a ventricular-Hisian accessory pathway. Pathological Q-waves are not developed (hence infarction is usually small unless subendocardium infarction). I also agree with Scott that although the premature complexes may appear narrow at first glance, they are actually 120 ms in duration when measured in lead II. ECG features include ST depression with T-wave changes (flat waves or inverted) These ST-depression may not reflect ischemic area. A pathological Q wave is > 25 the size of the R wave that follows it or > 2mm in height and > 40ms in width. These Q-waves are wider and deeper than normally. ![]() I agree with him that the sinus rate is unchanged by the VPBs – I can make out dissociated sinus P waves throughout the ventricular ectopic activity. Background: An abnormal Q wave is usually defined as an initial depression of the QRS complex having a duration of 40 ms and amplitude exceeding 25 of the following R wave in any contiguous leads on the 12lead electrocardiogram (ECG). As Scott says, this ECG seems to show sinus rhythm with 1st degree AV block and short runs of ventricular premature beats.
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