Mechanisms of fixed splitting of the second heart sound.

A phonocardiographic study of right bundle branch block, with special reference to the second heart sound.

The second heart sounds in 29 cases with right bundle branch block, mainly surgically induced, were studied. Three general types of the second sound were classified. Eleven cases revealed wide splitting of the second sound (0.05 sec. or more), and 14 cases showed narrow splitting less than 0.05 sec.), while 4 cases showed a single 2nd heart sound throughout the respiratory cycle. Ten cases reve...

Physiologic splitting of the second heart sound.

AN INCREASE in the magnitude of splitting of the 2 components of the second heart sound, as heard in the pulmonary area during inspiration, has been recognized for nearly a century.1 Recent reports2' 3 suggest that this phenomenon is due to a relative delay of pulmonary valve closure when the increased venous return during inspiration causes prolongation of right ventricular meehanical systole....

The splitting of the second heart sound in normal subjects and in patients with congenital heart disease.

demonstrated that the second heart sound results from closure of the semilunar valves.1 In 1865, on the basis of clinical observations, Potain indicated that the second heart sound may be split into two components and that the degree of this splitting may vary with respiration.2 More recently the studies of Leatham and collabora-tors3 4 have focused considerable attention on the splitting of th...

Second heart sound in normal subjects.

Splitting of the second heart sound in the pulmonary area into two components was first recognized by Potain (1866). In expiration, the two components fuse, while in inspiration delay of pulmonary valve closure (P2) occurs almost invariably in healthy subjects, enabling identification of aortic valve closure (A2) and P2, and hence comparison of the duration of right and left ventricular systole...

The mechanism of respiratory variation in splitting of the second heart sound.