Mid-diastolic, early diastolic and continuous murmurs
THE CONTEXT
The timing and acoustic character of these murmurs reflect the valves or flow pathways involved and guide auscultation.
Mid-diastolic murmurs
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Accelerated or turbulent flow across the mitral or tricuspid valve produces low-pitched murmurs that may be difficult to hear; evaluate them with the bell of the stethoscope.
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Mitral stenosis produces a mid-diastolic murmur at the apex and axilla, whereas tricuspid stenosis produces one at the left sternal border.
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Increased mitral flow may produce a mid-diastolic component, as in the to-and-fro murmur of severe mitral regurgitation.
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Increased tricuspid flow may produce a mid-diastolic murmur, as with a left-to-right shunt through a large atrial septal defect.
Early diastolic murmurs
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Early diastolic murmurs result from aortic or pulmonary regurgitation and have a soft, blowing quality with a decrescendo pattern.
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Evaluate them with the diaphragm of the stethoscope. They are best heard at the left sternal border with the patient sitting forwards in held expiration.
Continuous murmurs
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Continuous murmurs combine systolic and diastolic flow, as occurs with a persistent ductus arteriosus.
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Distinguish them from extracardiac noises, including arterial shunt bruits, venous hums associated with high venous flow in children, and pericardial friction rubs.