REN and Myocardial fibrosis: Hypertension may cause right ventricular dysfunction in the following way: First, overstimulation of the renin-angiotensin-aldosterone system and sympathetic nervous system produces vasoactive substances, oxidative stress, and endothelial dysfunction, which can induce accumulation of myocardial collagen and myocardial fibrosis, followed by remodeling of the left and right ventricles (20).