Second heart sound: a phono-echocardiographic correlation in 20 cardiac patients

In 20 cardiac patients, a study was made of the relationship between the second heart sound (S2) recorded by phonocardiography and the motion of the aortic valve recorded by simultaneous echocardiography. Since the first component of S2 coincided with closure of the aortic valve in all 20 patients, it is concluded that the origin of the first component of S2 may be related to aortic valve closure.