<prompt> The fouh hea sound is caused by?Closureiof the aoic and pulmonary valvesVibrations inihe ventricular wall during systoleVentricula fillingClosure of the mitral and tricuspid valves  <response>: A fouh hea sound is common in persons who derive benefit from atrial contraction for ventricular filling as a result of decreased ventricular wall compliance and increased resistance to ventricular filling. For example, a fouh hea sound is often heard in older patients with left ventricular hyperophy.Ref: Guyton and Hall textbook of medical physiology 13th edition. Page:284 