<prompt> Loud S1 is caused by-Calcified mitral valveMitral RegurgitationSho PR intervalBradycardia  <response>: Loud S1: Tachycardia Sho PR Interval. Mitral stenosis Tricuspid stenosis Soft S1: Bradycardia Prolonged PR Interval Aoic regurgitation Pulmonary regurgitation. Ref : Harrisons 20th edition pg 1563 