Right ventricular hypertrophy occurs when the right ventricular wall thickens due to chronic pressure overload, similar to that of left ventricular hypertrophy.
RVH is diagnosed on ECG in the presence of a R/S ratio of greater than 1 in lead V1 in the absence of other causes, or if the R wave in lead V1 is greater than 7 millimeters tall. The strain pattern occurs when the right ventricular wall is quite thick, and the pressure is high, as well. Strain causes ST segment depression and asymmetric T wave inversions in leads V1 to V3.
Other causes of an R/S ratio of greater than 1 in lead V1:
Posterior wall myocardial infarction (also causes ST segment depression in V1-V3, but T waves are symmetrically inverted, and the patient would be presenting with chest pains)
Right bundle branch block
Wolff-Parkinson-White Type A
Lead misplacement (if V1 is placed too high)
Isolated posterior wall hypertrophy (occurs in Duchenne’s muscular dystrophy)
1. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
2. Surawicz B, et al. AHA/ACCF/HRS Recommendations for the Standardization and Interpretation of the Electrocardiogram. Circulation. 2009; doi:10.1161/CIRCULATIONAHA.108.191095.