Chronic pulmonary heart disease usually results in right ventricular hypertrophy (RVH),[4] whereas acute pulmonary heart disease usually results in dilatation.[5] Hypertrophy is an adaptive response to a long-term increase in pressure. Individual muscle cells grow larger (in thickness) and change to drive the increased contractile force required to move the blood against greater resistance. Dilatation is a stretching (in length) of the ventricle in response to acute increased pressure.[6]