<prompt> Which of the following is true about fouh hea sound S4 :Can be heard by the unaided earFrequency is greater than 20 HzHeard during ventricular filling phaseHeard during ventricular ejection phase  <response>: Answer is C Heard during ventricular filling The fouh hea sound S4 is a low pitched presystolic sound produced in ventricles during ventricular filling. Fouh Hea Sound S4 Fouh Hea sound occurs in association with an effective atrial contraction It is presumably caused by inrush of blood into the ventricles when the atria contracts and hence it is also called the Atrial Hea Sound It is heard during the ventricular filling phase of the cardiac cycle PresystolicQ hea sound It is low pitched frequency usually 20 cyclesec or less-Guyton It is not audible to the unaided ear Normally the fouh hea sound can almost never be heard even with a stethascope because of its weakness and low frequency Guyton S4 becomes audible when diminished ventricular compliance increases the resistance to normal filling When audible the S4 is best heard with the bell of the stethescopeQ Pathologically may be seen in patients with Systemic Hypeension Ischaemic Hea Disease Pulmonic stenosis Right S4 Aoic Stenosis Mitral Regurgitation Pulmonary H.T Right S4 HOCM Physiologically may be seen in patients with Increasing age Loudest Best heard at the Left ventricular Apex when the patient is in left Lateral position It is accentuated by mild isotonic or isometric exercises in the supine position 