This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
All the above loud S1 caused by 
Select and explain. 
A. Calcified Valve, B. MVP, C. Sho PR interval, D. Dilation or widening of mitral valve after valvotomy
C: Sho PR interval
Answer: C: Sho PR interval 
Explanation: Ref Harrison 19 th ed pg 1447 The intensity of S1 is determined by the distance over which the ante- rior leaflet of the mitral valve must travel to return to its annular plane, leaflet mobility, left ventricular contractility, and the PR interval. S1 is classically loud in the early phases of rheumatic mitral stenosis (MS) and in patients with hyperkinetic circulatory states or sho PR inter- vals