Related Experiment Videos
Relation of third and fourth heart sounds to blood velocity during left ventricular filling
1Cardiac Department, Brompton Hospital, London.
Insights
The third heart sound closely aligns with peak left ventricular inflow velocity, indicating it arises from forces within the ventricle. The fourth heart sound precedes peak atrial inflow velocity, suggesting it originates from atrial systole.
Area of Science:
- Cardiology
- Biomedical Engineering
- Physiology
Background:
- Heart sounds provide valuable diagnostic information.
- Understanding the precise timing and origin of heart sounds is crucial for diagnosing cardiac conditions.
- Gallop sounds, specifically third and fourth heart sounds, are associated with abnormal ventricular filling dynamics.
Purpose of the Study:
- To investigate the temporal relationship between left ventricular inflow velocity and the timing of third and fourth heart sounds.
- To elucidate the underlying mechanisms generating third and fourth heart sounds based on their timing relative to blood flow dynamics.
Main Methods:
- Simultaneous phonocardiograms and continuous wave Doppler echocardiography were performed.
- Recordings were obtained from 48 patients with various heart diseases and 21 healthy children.
- Analysis focused on the precise timing differences between specific events in heart sounds and blood flow velocity peaks.
Main Results:
- The onset of the third heart sound closely correlated (within 5 ms) with peak left ventricular inflow velocity in most participants.
- The fourth heart sound consistently preceded peak atrial inflow velocity by approximately 55 ms.
- The onset of atrial flow and the atrial sound (likely the fourth sound) showed close agreement (within 1 ms).
Conclusions:
- Third heart sounds are closely linked to sudden deceleration of blood flow during rapid ventricular filling, originating within the ventricle.
- Fourth heart sounds are likely generated by the dissipation of forces during atrial systole, preceding atrial blood flow acceleration.
- These findings enhance the understanding of gallop sound generation and their relation to ventricular filling dynamics.
Abstract:
To investigate the relation between changes in left ventricular inflow velocity and the timing of third and fourth heart sounds, simultaneous phonocardiograms and continuous wave Doppler traces were recorded in 48 patients (aged 17-78) with heart disease and in 21 normal children. The onset of the first vibration of the third heart sound coincided with peak left ventricular inflow blood velocity to within 5 ms in all but two of the patients. The mean (SD) difference between the two events was 5 (5) ms, which did not differ significantly from zero. The relation was similar in patients with primary myocardial disease (11), and in those with valve disease (26), hypertension (five), and coronary artery disease (four). In the normal children, the mean interval was 2.5 (5) ms--not significantly different from zero. By contrast, the first deflection of the fourth heart sound consistently preceded the timing of peak atrial inflow velocity by 55 (10) ms. Agreement was much closer between the onset of atrial flow and the onset of the atrial sound (mean difference 1 (5) ms, not significantly different from zero). Gallop sounds seem to be closely related to changes in ventricular inflow velocity, and thus to the effects of forces acting on blood flow. The forces underlying the third sound seem to arise within the ventricle and are responsible for sudden deceleration of flow during rapid ventricular filling. The fourth sound, occurring at the onset of the "a" wave, is more likely to arise from dissipation of forces causing acceleration of blood flow--that is, atrial systole itself.