Q Wave

From Anvita Health Wiki

Contents 1 Introduction 2 Differential-diagnosis 3 Additional Terms 4 References

Introduction

• The 1st negative deflection in the QRS complex.

Differential-diagnosis

• physiologic or positional factors

• normal variant septal Q waves
• normal variant Q waves in V1 to V2, aVL, III & aVF
• left pneumothorax or dextrocardia

• loss of lateral R wave progression

• myocardial injury or infiltration

• acute processes

• myocardial ischemia or infarction
• myocarditis
• hyperkalemia

• chronic processes

• myocardial infarction
• idiopathic cardiomyopathy
• myocarditis
• amyloid
• tumor
• sarcoid
• scleroderma
• Chagas' disease
• echinococcus cyst

• ventricular hypertrophy or enlargement

• left ventricular hypertrophy

• poor R wave progression

• right ventricular hypertrophy

• poor or reversed R wave progression, especially with COPD

• hypertrophic cardiomyopathy

• may simulate anterior, inferior, posterior or lateral myocardial infarcts

• conduction abnormalities

• left bundle branch block (poor R wave progression)
• Wolf-Parkinson-White syndrome

• Abnormal QRS deflection associated with myocardial infarction:
• A Q wave should be at least 30 ms in duration, > 1/4 the size of the R-wave & present in 2/3 inferior leads.
• =
• Q wave infarction
  
• V1, V2 anteroseptal
• V1, V2 (if tall R) posterior
• V3, V4 apical
• I, aVL, V5, V6 anterolateral
• II, III, aVF inferior
  
• V1, V2, V3 Wolf-Parkinson-White ( WPW) =.

Additional Terms

• ECG QRS complex
• electrocardiogram (ECG, EKG)
• septal Q wave

References

1. Harrison's Principles of Internal Medicine, 13th ed. Isselbacher et al (eds), McGraw-Hill Inc. NY, 1994, pg 965
2. Harrison's Principles of Internal Medicine, 13th ed. Companion Handbook, Isselbacher et al (eds), McGraw-Hill Inc. NY, 1995, pg 332

Q wave