| Download the amazing global Makindo app: Android | Apple | |
|---|---|
| MEDICAL DISCLAIMER: Educational use only. Not for diagnosis or management. See below for full disclaimer. |
ECG - Pathological Q waves
Related Subjects: |ECG Basics |ECG Axis |ECG Analysis |ECG LAD |ECG RAD |ECG Low voltage |ECG Pathological Q waves |ECG ST/T wave changes |ECG LBBB |ECG RBBB |ECG short PR |ECG Heart Block |ECG Asystole and P wave asystole |ECG QRS complex |ECG ST segment |ECG: QT interval |ECG: LVH |ECG RVH |ECG: Bundle branch blocks |ECG Dominant R wave in V1 |ECG Acute Coronary Syndrome |ECG Crib sheets
📖 Definition
- 📏 A Q wave is pathological if its depth is ≥25% of the associated R wave.
- 🧭 Must be present in ≥2 contiguous leads (isolated Q in lead III is a common normal variant).
- ⏱️ Any Q wave in leads V1–V3 with duration >0.02 s is usually pathological.
- 🔍 Tiny R-deflection may precede the Q (sometimes subtle and easily missed).
- 🧩 Pathological Q waves are often broad and deep — but must be seen in contiguous leads.
⚠️ Causes of Pathological Q Waves
- ❤️ Transmural MI (STEMI) – classic cause
- ⚡ Left Bundle Branch Block (LBBB)
- 🔄 Wolff-Parkinson-White (WPW) – pseudoinfarct pattern
- 💪 Hypertrophic Cardiomyopathy
- 🫀 Ischaemic Cardiomyopathy
- 🔥 Myocarditis
- ↔️ Dextrocardia (axis reversal mimics infarct Qs)
💡 Teaching Pearls
✔️ Q waves = marker of myocardial necrosis (dead, electrically silent tissue). ✔️ Pathological Qs usually persist for life after infarction, even when ST/T changes resolve. ✔️ Always check calibration and rule out mimics (LBBB, WPW, HCM) before diagnosing “old MI.”
📚 ECG References
| The content on this website is provided for educational and informational purposes only to support exam preparation (e.g., MLA, MRCP, USMLE) and learning. This is NOT medical advice, diagnosis, treatment, or professional guidance. It does not replace consultation with a qualified healthcare professional, official guidelines (e.g., NICE, GMC, BNF), or supervised clinical practice. Always verify information with current, authoritative sources. Makindo and its contributors accept no liability for any reliance on this content, including errors, omissions, or any resulting harm, loss, or consequences. By using this site, you agree to these terms. |
|
|
Categories
- A Level
- About
- Acute Medicine
- Anaesthetics and Critical Care
- Anatomy
- Anatomy and Physiology
- Biochemistry
- Book
- Cardiology
- Collections
- CompSci
- Crib Sheets
- Crib sheets
- Dental
- Dermatology
- Differentials
- Drugs
- ENT
- Education
- Electrocardiogram
- Embryology
- Emergency Medicine
- Endocrinology
- Ethics
- Foundation Doctors
- GCSE
- Gastroenterology
- General Practice
- Genetics
- Geriatric Medicine
- Guidelines
- Gynaecology
- Haematology
- Hepatology
- Immunology
- Infectious Diseases
- Infographic
- Investigations
- Lists
- Mandatory Training
- Medical Students
- Microbiology
- Nephrology
- Neurology
- Neurosurgery
- Nutrition
- OSCE
- OSCEs
- Obstetrics
- Obstetrics Gynaecology
- Oncology
- Ophthalmology
- Oral Medicine and Dentistry
- Orthopaedics
- Paediatrics
- Palliative
- Pathology
- Pharmacology
- Physiology
- Procedures
- Psychiatry
- Public Health
- Radiology
- Renal
- Respiratory
- Resuscitation
- Revision
- Rheumatology
- Statistics and Research
- Stroke
- Surgery
- Toxicology
- Trauma and Orthopaedics
- USMLE
- Urology
- Vascular Surgery