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Genesis of Still's murmurs: a controlled Doppler echocardiographic study
1Royal Hospital for Sick Children, Bristol.
Insights
Innocent systolic murmurs in children are linked to increased blood flow and vibrations in the left ventricle, not aortic size. Left ventricular bands
Area of Science:
- Pediatric Cardiology
- Echocardiography
- Hemodynamics
Background:
- The precise mechanisms behind innocent systolic murmurs in children remain unclear.
- Factors such as left ventricular bands and altered flow dynamics are suspected contributors.
Purpose of the Study:
- To assess the roles of left ventricular bands and increased flow indices in innocent systolic murmurs.
- To investigate evidence of turbulence associated with these factors.
Main Methods:
- Prospective cross-sectional echocardiography with Doppler and color flow mapping.
- 40 children with innocent murmurs were compared to 40 matched controls.
- Analysis included left ventricular bands, flow velocities, and vibratory phenomena.
Main Results:
- Left ventricular bands were more common in children with murmurs (70%) versus controls (48%).
- Higher aortic peak flow velocities, flow integrals, and stroke volumes were observed in murmur cases.
- Vibratory phenomena in the left ventricle were more frequent in cases but not linked to bands.
Conclusions:
- Innocent systolic murmurs correlate with elevated aortic flow volume/velocity and left ventricular vibrations.
- Relative bradycardia was associated with innocent murmurs.
- The significance of left ventricular bands in murmur genesis remains uncertain.
Objective:
The origin of innocent systolic murmurs is uncertain. This study was designed to evaluate the relative contribution in the same subjects of the main factors implicated in the genesis of vibratory innocent systolic murmurs--that is, the presence of left ventricular bands and increased left ventricular flow indices--and to examine evidence for turbulence in relation to these findings.
Patients:
40 children with innocent systolic murmurs and 40 paired controls without murmurs were matched for age and body surface area.
Design:
These subjects were examined prospectively by cross sectional echocardiography with pulsed and continuous wave Doppler and colour flow mapping.
Setting:
A tertiary referral centre for paediatric cardiology.
Results:
Left ventricular bands were significantly more prevalent in patients with innocent murmurs (70%) than in controls (48%) but only if apical bands were included (p = 0.039). Cases had significantly higher aortic peak flow velocities (p less than 0.001), flow integrals (p = 0.001), and stroke volumes (p = 0.014), and significantly lower heart rates (p = 0.033) than controls. There were no significant differences between cases and controls in mean aortic diameter, cardiac output, or ejection fraction. There was no evidence of turbulence in the left ventricle or outflow tract in any individual but curvilinear periodic vibrations and audible "whoops" were detected in the left ventricle by pulsed wave Doppler echocardiography. These were significantly more common in cases than controls (p less than 0.01) but were not related to the presence of bands.
Conclusions:
Innocent systolic murmurs were unrelated to aortic size but they were strongly associated with higher aortic flow volume and velocity, with relative bradycardia, and with evidence of vibratory phenomena in the left ventricle. The role of left ventricular bands remains uncertain.