DIASTOLIC MURMURS

DIASTOLIC MURMURS


Diastolic murmurs are heart murmurs that occur during diastole, the phase of the cardiac cycle when the heart relaxes and the ventricles fill with blood. Diastolic murmurs are less common than systolic murmurs and typically indicate significant pathology involving the heart valves, particularly aortic or pulmonary regurgitation and mitral or tricuspid stenosis.

Types of Diastolic Murmurs:

1. Aortic Regurgitation (AR)

  • Description: Aortic regurgitation occurs when the aortic valve does not close properly during diastole, causing blood to flow back into the left ventricle.
  • Murmur Characteristics:
    • Type: Early diastolic, decrescendo
    • Location: Best heard at the left sternal border, especially in the 3rd or 4th intercostal space.
    • Radiation: May radiate toward the apex or along the left sternal border.
    • Associated Findings: Wide pulse pressure, water-hammer pulse, and displaced apical impulse due to left ventricular dilation.
  • Mechanism: The backward flow of blood from the aorta into the left ventricle leads to volume overload, left ventricular dilation, and hypertrophy.

2. Pulmonic Regurgitation (PR)

  • Description: Pulmonic regurgitation occurs when the pulmonary valve fails to close properly, allowing blood to flow back into the right ventricle during diastole.
  • Murmur Characteristics:
    • Type: Early diastolic, decrescendo
    • Location: Best heard at the left upper sternal border.
    • Radiation: None
    • Associated Findings: Right ventricular heave, signs of right-sided heart failure (e.g., peripheral edema, ascites).
  • Mechanism: Similar to aortic regurgitation but involves the right side of the heart, leading to right ventricular volume overload and dilation.

3. Mitral Stenosis (MS)

  • Description: Mitral stenosis results from narrowing of the mitral valve, restricting blood flow from the left atrium into the left ventricle during diastole.
  • Murmur Characteristics:
    • Type: Mid-diastolic, low-pitched rumble with an opening snap
    • Location: Best heard at the apex, often with the patient in the left lateral decubitus position.
    • Radiation: None
    • Associated Findings: Loud S1, opening snap after S2, signs of pulmonary hypertension (e.g., dyspnea, hemoptysis).
  • Mechanism: The restricted opening of the mitral valve causes turbulent blood flow, leading to a characteristic low-pitched rumbling murmur.

4. Tricuspid Stenosis (TS)

  • Description: Tricuspid stenosis occurs when the tricuspid valve is narrowed, restricting blood flow from the right atrium to the right ventricle.
  • Murmur Characteristics:
    • Type: Mid-diastolic, rumbling
    • Location: Best heard at the lower left sternal border (LLSB).
    • Radiation: None
    • Associated Findings: Increased intensity with inspiration (Carvallo’s sign), signs of right-sided heart failure.
  • Mechanism: The obstruction to flow from the right atrium into the right ventricle during diastole causes a low-pitched murmur.
Table: Showing causes of diastolic murmurs and differentiation

Condition

Type of Murmur

Location

Radiation

Character

Associated Findings

Aortic Regurgitation (AR)

Early Diastolic, Decrescendo

Left sternal border (3rd/4th ICS)

Apex, along the left sternal border

High-pitched, blowing, decrescendo

Wide pulse pressure, bounding pulse, displaced apical impulse, Corrigan’s pulse

Pulmonic Regurgitation (PR)

Early Diastolic, Decrescendo

Left upper sternal border

None

High-pitched in pulmonary hypertension, low-pitched in normal pulmonary pressure

RV heave, signs of right-sided heart failure, Graham-Steell murmur in pulmonary hypertension

Mitral Stenosis (MS)

Mid-Diastolic, Low-pitched Rumble

Apex, in left lateral decubitus position

None

Low-pitched, rumbling with an opening snap

Loud S1, opening snap, signs of pulmonary hypertension, atrial fibrillation

Tricuspid Stenosis (TS)

Mid-Diastolic, Low-pitched Rumble

Lower left sternal border (LLSB)

None

Low-pitched, increases with inspiration

Elevated JVP, hepatomegaly, peripheral edema, often associated with tricuspid regurgitation

Atrial Myxoma

Mid-Diastolic

Apex

None

Variable pitch, tumor plop

Positional changes in murmur intensity, signs of systemic embolism

Austin Flint Murmur (AR)

Mid-Diastolic, Low-pitched Rumble

Apex

None

Mimics mitral stenosis but no opening snap

Associated with severe aortic regurgitation, absence of mitral stenosis

Clinical Differentiation:

  • Aortic Regurgitation: High-pitched, blowing murmur best heard at the left sternal border, often associated with a wide pulse pressure and characteristic signs such as Corrigan’s pulse (bounding pulse). It radiates toward the apex or left sternal border.
  • Pulmonic Regurgitation: Best heard at the left upper sternal border. If pulmonary hypertension is present, the murmur is high-pitched (Graham-Steell murmur). If the pulmonary pressures are normal, the murmur is softer and lower-pitched.
  • Mitral Stenosis: Characterized by a low-pitched rumbling murmur with an opening snap, best heard at the apex with the patient in the left lateral decubitus position. The murmur is often accompanied by signs of atrial fibrillation and pulmonary hypertension.
  • Tricuspid Stenosis: A low-pitched, rumbling murmur that increases with inspiration (Carvallo’s sign). It is best heard at the lower left sternal border and often accompanied by signs of right-sided heart failure.
  • Atrial Myxoma: This rare condition can mimic mitral stenosis but may have a characteristic tumor plop on auscultation. The murmur intensity may change with position, and systemic embolism is a common feature.
  • Austin Flint Murmur: Seen in severe aortic regurgitation, this mid-diastolic murmur is heard at the apex and mimics mitral stenosis but lacks an opening snap. It results from the regurgitant aortic jet impinging on the anterior leaflet of the mitral valve, preventing normal valve closure.
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