Right Ventricular Hypertrophy (RVH) & Right Bundle Branch Block (RBBB) ECG Criteria
Jul 19, 2026Diagnosing right ventricular hypertrophy (RVH) in the presence of a right bundle branch block (RBBB) can be difficult because both conditions produce a prominent terminal R' wave in lead V1. One of the most useful criteria is an R' wave greater than 15 mm in V1.
An isolated RBBB delays right ventricular activation, producing the characteristic rSR' morphology. However, because right ventricular myocardial mass remains normal, the terminal R' wave typically remains relatively modest in amplitude. When the right ventricle is hypertrophied, there is substantially more myocardium to depolarize during this delayed activation. As a result, the terminal rightward electrical vector becomes much larger, producing an unusually tall R' wave.
An R' amplitude exceeding 15 mm in V1 therefore suggests that the delayed depolarization is being generated by an enlarged right ventricle rather than by conduction delay alone. Anatomically, this reflects an increase in right ventricular muscle mass that amplifies the terminal depolarization vector once activation finally reaches the right ventricle.
Although no single ECG criterion is perfectly sensitive or specific, an R' wave greater than 15 mm in the setting of RBBB should raise strong suspicion for underlying RVH, particularly in patients with pulmonary hypertension, congenital heart disease, or other causes of chronic right ventricular pressure overload.
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