Mitral components of the first heart sound.

Abstract

The previously recognized variations in the timing and intensity of Mi, which may be associated with mitral valve pathology, myocardial decompensation, and with disturbances of conduction and rhythm, are briefly discussed and explained.Though it is generally accepted that the two components of the second heart sound depend on aortic and pulmonary valve closure (Leatham, 1954; Delman, i967), the number of components of the first sound and their mechanism of production remain disputed and ill understood (Dock, I965 Delman, I967). It has been shown by phonocardiography (Rappaport and Sprague, I942; Counihan et al., I95I; Dayem and Raftery, I966; Rushmer, 1970) that the normal first heart sound has at least 4 vibrations or groups of vibrations (Fig. i). These comprise initial low frequency vibrations, two higher pitched 'major vibrations', and then low frequency 'after vibrations.' Though the early low frequency vibrations are clinically audible in some instances (Kincaid-Smith and Barlow, I959a), it is the two major components only which are heard and assessed by most clinicians. The 'after vibrations' are probably never audible.

Mechanisms of Abnormal Systolic Motion of the Interventricular Septum During Left Bundle-Branch Block

“…Furthermore, we investigated the temporal relationship between interruption of preejection septal shortening and the time of mitral valve closure, defined as the peak of the c-wave in the left atrial pressure trace. 12,13 …”

Non-invasive observations on initial low frequency vibrations of the first heart sound--correlation with the 'presystolic' murmur in mitral stenosis.

“…The initial low frequency component of the first heart sound has been studied for more than 150 years (Orias, 1936;Eckstein, 1937;Smith et al, 1941;Lakier et al, 1970;Luisada and Argano, 1971;Lakier et al, 1972a, b;Armstrong and Gotsman, 1973). We hope to show that the sound is more than just an abstruse phonocardiographic finding but has clinical significance in that it is responsible for the short crescendo, so-called 'presystolic', murmur of mitral stenosis in atrial fibrillation, as suggested by Tavel and Bonner (Bonner et al, 1976;Tavel and Bonner, 1976).…”

“…We hope to show that the sound is more than just an abstruse phonocardiographic finding but has clinical significance in that it is responsible for the short crescendo, so-called 'presystolic', murmur of mitral stenosis in atrial fibrillation, as suggested by Tavel and Bonner (Bonner et al, 1976;Tavel and Bonner, 1976). This sound, which occurs near the peak of the R wave of the electrocardiogram and at the crossover point of the left atrial and ventricular pressures, has been termed 'M' by Lakier et al (1970) and '0' by Luisada and Argano (1971) (Fig. 1).…”

“…1). In contrast, the later higher frequency component of the first heart sound (Ml) occurs at the time of the left atrial C wave (Lakier et al, 1972a, b).…”

“…Received for publication 12 May 1977 (Lakier et al, 1970(Lakier et al, , 1972a. Other studies have suggested that muscular contraction producing sudden deceleration of blood flow across the atrioventricular orifice is more likely to produce the sound.…”