What is the differential diagnosis of tall R waves in lead V1?
From Mattu, Brady, et al., Prominent R Wave in Lead V1: Electrocardiographic Differential Diagnosis. Am J Emerg Med 2001; 19:504-513. PMID: 11593472
- Right bundle branch block
- Left ventricular ectopy
- Right ventricular hypertrophy
- Acute right ventricular dilation (acute right heart strain)
- Type A Wolff-Parkinson-White syndrome
- Posterior myocardial infarction
- Hypertrophic cardiomyopathy
- Progressive muscular dystrophy
- Misplaced precordial leads
- Normal varient
Can you identify all of these conditions?
RBBB is characterized by a superaventricular rhythm with a QRS duration = or > 120 ms, a terminal R wave in lead V1, and a slurred S wave in lead I. See an example here.
RVH is characterized by a right axis deviation, a tall R wave in lead V1, and often a right ventricular “strain pattern” in the right precordial leads. See an example here.
WPW Type A is characterized by a short PR interval, delta waves, and positive concordance of the precordial leads. See an example from the ECGPedia here.
Posterior MI is often associated with inferior MI. When present, the R wave in lead V1 is at the very beginning of the QRS complex (not the end of the QRS complex as is the case with RBBB). We’ll cover this topic more in-depth in a future discussion.
As for “left ventricular ectopy” just remember that ventricular complexes that originate in the left ventricle show RBBB morphology in lead V1. Conversely, ventricular complexes that originate in the right ventricle show LBBB morphology in lead V1.
Among other things, this means you can determine which ventricle a PVC comes from if you’re monitoring lead V1.