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Dr. Mete ALPASLAN
QRS Complex
When measuring QRS width, the lead with the widest QRS complex is chosen.
The width of the QRS increases as the left ventricular dimensions increase.
The width of the QRS complexes in precordial leads are wider than those of the limb leads.
The QRS width is accepted to be increased if it is
- 90 ms or more in children < 4 years of age,
- 100 ms or more in children between 4-16 years of age,
- > 110 ms in subjects > 16 years of age.
Q waves as normal variants
Isolated Q wave in lead III
QS pattern in lead C1 (V1)
Q wave in lead aVL (in vertical hearts)
Q waves in inferior and left lateral leads in children
Pathologic Q waves: Q/R ratio ≥ 0.25 or ≥ 40 ms in duration in two or more leads (excluding III and aVR).
In some patients with acute pericarditis, PR segment depression may give the impression of pathological q waves, at first glance. In the setting of widespread ST segment elevation of acute pericarditis, possibility of such a false diagnosis high.
Causes of wide QRS complex
Left ventricular hypertrophy
Bundle branch blocks
Hyperkalemia
Wolff-Parkinson-White (WPW) syndrome
Cardiac pacemaker stimulation (except His bundle pacing)
References
J Am Coll Cardiol 2017;69:1057-1075. (International Recommendations for Electrocardiographic Interpretation in Athletes.) (free full-text)
Circulation 2009;119;e235-e240.
ECG 1. The ECG above belongs to an apparently healthy, 7 years-old boy.
His echocardiogram is normal.
The narrow q waves in leads II, III, aVF, V5 and V6 are benign.
Click here for a more detailed ECG
ECG 2. The compact ECG above belongs to an apparently healthy, 18 years-old lean male.
His echocardiogram is normal.
The narrow q waves in leads II, III, aVF, V5 and V6 are benign.
ECG 3. Above is an ECG from a 25 years-old man with atypical chest pain.
Most of the leads show PR segment depression while lead aVR shows PR segment elevation.
Most of the leads also show ST segment elevation.
At first glance, PR segment depression in leads II and aVF may seem as "pathological q waves".
His Troponin levels were above upper limit of normal. His ECHOcardiography examination was normal.
He was diagnosed as acute perimyocarditis.
This case shows that PR segment depression must not be confused with pathological q waves.
Click here for a more detailed ECG
When measuring QRS width, the lead with the widest QRS complex is chosen.
The width of the QRS increases as the left ventricular dimensions increase.
The width of the QRS complexes in precordial leads are wider than those of the limb leads.
The QRS width is accepted to be increased if it is
- 90 ms or more in children < 4 years of age,
- 100 ms or more in children between 4-16 years of age,
- > 110 ms in subjects > 16 years of age.
Q waves as normal variants
Isolated Q wave in lead III
QS pattern in lead C1 (V1)
Q wave in lead aVL (in vertical hearts)
Q waves in inferior and left lateral leads in children
Pathologic Q waves: Q/R ratio ≥ 0.25 or ≥ 40 ms in duration in two or more leads (excluding III and aVR).
In some patients with acute pericarditis, PR segment depression may give the impression of pathological q waves, at first glance. In the setting of widespread ST segment elevation of acute pericarditis, possibility of such a false diagnosis high.
Causes of wide QRS complex
Left ventricular hypertrophy
Bundle branch blocks
Hyperkalemia
Wolff-Parkinson-White (WPW) syndrome
Cardiac pacemaker stimulation (except His bundle pacing)
References
J Am Coll Cardiol 2017;69:1057-1075. (International Recommendations for Electrocardiographic Interpretation in Athletes.) (free full-text)
Circulation 2009;119;e235-e240.
ECG 1. The ECG above belongs to an apparently healthy, 7 years-old boy.
His echocardiogram is normal.
The narrow q waves in leads II, III, aVF, V5 and V6 are benign.
Click here for a more detailed ECG
ECG 2. The compact ECG above belongs to an apparently healthy, 18 years-old lean male.
His echocardiogram is normal.
The narrow q waves in leads II, III, aVF, V5 and V6 are benign.
ECG 3. Above is an ECG from a 25 years-old man with atypical chest pain.
Most of the leads show PR segment depression while lead aVR shows PR segment elevation.
Most of the leads also show ST segment elevation.
At first glance, PR segment depression in leads II and aVF may seem as "pathological q waves".
His Troponin levels were above upper limit of normal. His ECHOcardiography examination was normal.
He was diagnosed as acute perimyocarditis.
This case shows that PR segment depression must not be confused with pathological q waves.
Click here for a more detailed ECG