Pathogenesis and diagnosis of Q waves on the electrocardiogram
- Ary L Goldberger, MD
Ary L Goldberger, MD
- Section Editor — Electrocardiography
- Professor of Medicine
- Harvard Medical School
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. Although prominent Q waves are a characteristic finding in myocardial infarction, they can also be seen in a number of noninfarct settings. Failure to appreciate the other causes of Q waves can lead to important diagnostic errors. (See "Basic principles of electrocardiographic interpretation".)
●Physiologic and positional effects
●Myocardial injury or replacement
●Ventricular enlargementTo continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:
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- PHYSIOLOGIC AND POSITIONAL EFFECTS
- MYOCARDIAL DAMAGE AND REPLACEMENT
- ALTERED CONDUCTION
- Left bundle branch block
- Wolff-Parkinson-White syndrome
- Left anterior fascicular (hemi-) block
- VENTRICULAR ENLARGEMENT
- Chronic obstructive pulmonary disease
- Acute pulmonary embolism
- Hypertrophic cardiomyopathy
- Depressed left ventricular function
- AIDS TO DIFFERENTIAL DIAGNOSIS