hypertension. Causes for incomplete right bundle branch block are exercise-induced right ventricular remodeling, increased RV free wall thickness, especially in athletes due to prolonged endurance exercise. Diagnosis The criteria to diagnose a right bundle branch block on the electrocardiogram: The heart rhythm must originate above the ventricles (i.e., sinoatrial node, atria or atrioventricular node) to activate the conduction system at the correct point. The QRS duration must be more than 100 ms (incomplete block) or more than 120 ms (complete block). There should be a terminal R wave in lead V1 (often called "R prime," and denoted by R, rR', rsR', rSR', or qR). There must be a prolonged S wave in leads I and V6 (sometimes referred to as a "slurred" S wave). The T wave should be deflected opposite the terminal deflection of the QRS complex. This is known as appropriate T wave discordance with bundle branch block. A concordant T wave may suggest ischemia or myocardial infarction. Treatment The underlying condition may be treated by medications to control hypertension or diabetes, if they are the primary underlying cause. If coronary arteries are blocked, an invasive coronary angioplasty may relieve the impending RBBB. Epidemiology Prevalence of RBBB increases with age due to changes in the heart's conduction system. It's estimated up to 11.3% of the population by the age of 80 have RBBB. Gallery See also Intraventricular block Bundle branch block Left bundle branch block References External links Cardiac arrhythmia fr:Bloc de branche#Bloc de branche droit