[Possible mechanism of production of the musical second heart sound and its clinical significance].

Abstract

To investigate the predisposing factors and the clinical significance of the musical aortic component of the second heart sound (musical S2), 18 patients with musical S2 (musical group) among the consecutive 2,000 patients with phonocardiographic examination were noninvasively studied by analyzing underlying diseases, phonocardiographic findings, organic changes of the aortic valve, severity of aortic regurgitation and left ventricular dysfunction. Organic changes of the aortic valve were assessed by two-dimensional echocardiography, and aortic regurgitation was assessed by color Doppler flow imaging. Twenty-two normal subjects (normal group) and 17 patients with essential hypertension (hypertensive group) served as controls. Mean ages were matched among the three groups. 1. Left ventricular dilatation (seven patients) and hypertension (six patients) were the dominant part of underlying disease in the musical group. 2. Musical S2 was classified in the following two types based on the phonocardiographic characteristics; musical vibrations followed immediately after the accentuated S2, and the S2 which was replaced by regular vibratory waves. 3. Frequency of the musical vibrations ranged from 120 to 200 Hz, and its duration ranged from 60 to 120 msec. Amplitude of the musical vibrations decreased by inhalation of amyl nitrite, but increased by infusion of methoxamine. In a case with mild rheumatic valve disease, methoxamine induced marked intensification of the amplitude and prolongation of the duration of the musical vibrations, finally giving a typical cooing murmur. 4. Echo intensity of the aortic valve tended to be higher in the musical group than in the other two groups. 5. Echocardiographically, aortic regurgitation appeared more frequently in the musical group (88%) than in the normal (36%) and hypertensive (41%) groups. Area of the aortic regurgitant signal was significantly larger in the musical group (4.1 +/- 1.4 cm2) than in the normal (1.2 +/- 0.8 cm2) and hypertensive (2.3 +/- 1.2 cm2) groups. 6. Left ventricular end-diastolic dimension was significantly larger in the musical group (5.8 +/- 0.6 cm) than in the normal (4.7 +/- 0.5 cm) and hypertensive (4.8 +/- 0.7 cm) groups. Fractional shortening of the left ventricle was significantly smaller in the musical group (26 +/- 10%) than in the normal (37 +/- 5%) and hypertensive (37 +/- 8%) groups. In a case of the musical group, musical vibrations following the S2, which was large in amplitude at the state of heart failure, decreased markedly after the recovery from heart failure.(ABSTRACT TRUNCATED AT 400 WORDS)