Cardiac murmurs are abnormal heart sounds caused by turbulent blood flow, often due to valvular or structural heart conditions. The best location to auscultate each murmur, its common causes, and maneuvers that affect its intensity are listed below. Auscultation is typically performed with a stethoscope, and the locations correspond to specific anatomical areas on the chest. Maneuvers alter murmur intensity by changing preload, afterload, or cardiac dynamics.
1. Aortic Stenosis (AS)
- Best Location: Right 2nd intercostal space (right upper sternal border)
- Cause: Narrowing of the aortic valve, often due to calcific degeneration (elderly), congenital bicuspid valve, or rheumatic heart disease
- Murmur Characteristics: Harsh, crescendo-decrescendo systolic murmur, often radiating to carotids
- Maneuvers:
- Increases: Increased preload (e.g., squatting, leg raise) or afterload (e.g., handgrip) → Increases flow across stenotic valve
- Decreases: Decreased preload (e.g., Valsalva, standing) → Reduces flow across valve
- Note: Handgrip may paradoxically decrease if severe AS causes heart failure
2. Aortic Regurgitation (AR)
- Best Location: Left 3rd–4th intercostal space (left sternal border), with patient leaning forward
- Cause: Aortic root dilation (e.g., Marfan syndrome, hypertension), bicuspid aortic valve, endocarditis, or rheumatic heart disease
- Murmur Characteristics: High-pitched, decrescendo diastolic murmur
- Maneuvers:
- Increases: Increased afterload (e.g., handgrip) → Increases regurgitant flow; sitting forward with expiration
- Decreases: Decreased afterload (e.g., vasodilators) or preload (e.g., Valsalva) → Reduces regurgitant volume
3. Mitral Stenosis (MS)
- Best Location: Apex (5th intercostal space, midclavicular line), with patient in left lateral decubitus position
- Cause: Rheumatic heart disease (most common), congenital stenosis, or left atrial myxoma
- Murmur Characteristics: Low-pitched, rumbling diastolic murmur, often with opening snap
- Maneuvers:
- Increases: Increased preload (e.g., exercise, leg raise) → Increases flow across stenotic valve; left lateral position enhances audibility
- Decreases: Decreased preload (e.g., Valsalva, standing) → Reduces flow across valve
4. Mitral Regurgitation (MR)
- Best Location: Apex (5th intercostal space, midclavicular line), often radiating to axilla
- Cause: Mitral valve prolapse, ischemic heart disease, endocarditis, rheumatic heart disease, or dilated cardiomyopathy
- Murmur Characteristics: Holosystolic, blowing murmur
- Maneuvers:
- Increases: Increased afterload (e.g., handgrip) or preload (e.g., squatting) → Increases regurgitant flow
- Decreases: Decreased preload (e.g., Valsalva, standing) or afterload (e.g., vasodilators) → Reduces regurgitant volume
5. Mitral Valve Prolapse (MVP)
- Best Location: Apex (5th intercostal space, midclavicular line)
- Cause: Myxomatous degeneration of mitral valve leaflets, often idiopathic or associated with connective tissue disorders (e.g., Marfan syndrome)
- Murmur Characteristics: Mid-to-late systolic murmur, often preceded by a midsystolic click
- Maneuvers:
- Increases: Decreased preload (e.g., standing, Valsalva) → Earlier prolapse, longer murmur
- Decreases: Increased preload (e.g., squatting, leg raise) → Delays prolapse, shortens murmur
6. Pulmonic Stenosis (PS)
- Best Location: Left 2nd intercostal space (left upper sternal border)
- Cause: Congenital (e.g., tetralogy of Fallot), carcinoid syndrome, or rheumatic heart disease
- Murmur Characteristics: Harsh, crescendo-decrescendo systolic murmur
- Maneuvers:
- Increases: Increased preload (e.g., squatting, inspiration) → Increases flow across stenotic valve
- Decreases: Decreased preload (e.g., Valsalva, standing) → Reduces flow across valve
7. Pulmonic Regurgitation (PR)
- Best Location: Left 2nd–3rd intercostal space (left upper sternal border)
- Cause: Pulmonary hypertension, congenital defects, or endocarditis
- Murmur Characteristics: High-pitched, decrescendo diastolic murmur (Graham Steell murmur if due to pulmonary hypertension)
- Maneuvers:
- Increases: Inspiration → Increases right heart volume, enhancing regurgitant flow
- Decreases: Expiration or decreased preload (e.g., Valsalva) → Reduces right heart volume
8. Tricuspid Stenosis (TS)
- Best Location: Lower left sternal border (4th–5th intercostal space)
- Cause: Rheumatic heart disease, carcinoid syndrome, or congenital defects
- Murmur Characteristics: Low-pitched, rumbling diastolic murmur
- Maneuvers:
- Increases: Inspiration → Increases right heart preload, enhancing flow across stenotic valve
- Decreases: Expiration or decreased preload (e.g., Valsalva) → Reduces flow
9. Tricuspid Regurgitation (TR)
- Best Location: Lower left sternal border (4th–5th intercostal space)
- Cause: Right ventricular dilation (e.g., pulmonary hypertension), endocarditis, rheumatic heart disease, or Ebstein anomaly
- Murmur Characteristics: Holosystolic, blowing murmur
- Maneuvers:
- Increases: Inspiration → Increases right heart preload, enhancing regurgitant flow
- Decreases: Expiration or decreased preload (e.g., Valsalva) → Reduces regurgitant volume
10. Hypertrophic Cardiomyopathy (HCM)
- Best Location: Left 3rd–4th intercostal space (left sternal border)
- Cause: Genetic mutation causing left ventricular hypertrophy, leading to dynamic left ventricular outflow tract (LVOT) obstruction
- Murmur Characteristics: Harsh, crescendo-decrescendo systolic murmur
- Maneuvers:
- Increases: Decreased preload (e.g., Valsalva, standing) or decreased afterload (e.g., vasodilators) → Increases LVOT obstruction
- Decreases: Increased preload (e.g., squatting, leg raise) or increased afterload (e.g., handgrip) → Reduces LVOT obstruction
11. Ventricular Septal Defect (VSD)
- Best Location: Left 3rd–4th intercostal space (left sternal border)
- Cause: Congenital defect, post-myocardial infarction, or traumatic rupture of ventricular septum
- Murmur Characteristics: Harsh, holosystolic murmur
- Maneuvers:
- Increases: Increased preload (e.g., squatting) → Increases shunt flow
- Decreases: Decreased preload (e.g., Valsalva) → Reduces shunt flow
- Note: Small VSDs may have louder murmurs due to higher velocity flow
12. Atrial Septal Defect (ASD)
- Best Location: Left 2nd–3rd intercostal space (left upper sternal border)
- Cause: Congenital defect (e.g., ostium secundum, primum), often asymptomatic until adulthood
- Murmur Characteristics: Soft systolic murmur (due to increased flow across pulmonic valve), often with fixed splitting of S2
- Maneuvers:
- Increases: Inspiration → Increases right heart volume, enhancing flow
- Decreases: Expiration → Reduces right heart volume
- Note: Murmur is not from the defect itself but from increased pulmonic flow
Summary of Maneuvers
- Inspiration: Increases right-sided murmurs (e.g., TR, TS, PR, ASD) by increasing right heart preload.
- Expiration: Enhances left-sided murmurs (e.g., AR, MR) by reducing lung interference.
- Valsalva (strain phase): Decreases preload, reducing most murmurs except HCM and MVP (which increase).
- Squatting/Leg Raise: Increases preload and afterload, increasing most murmurs except HCM and MVP (which decrease).
- Handgrip: Increases afterload, increasing regurgitant murmurs (e.g., MR, AR) but may decrease HCM murmur.
- Standing: Decreases preload, reducing most murmurs except HCM and MVP.
Notes
- Auscultation Tips: Use the diaphragm for high-pitched murmurs (e.g., AR, MR) and the bell for low-pitched murmurs (e.g., MS, TS). Position the patient appropriately (e.g., left lateral for MS, forward for AR).
- Pathophysiology: Murmur intensity depends on pressure gradients and flow rates. For example, severe stenosis may produce softer murmurs due to reduced flow.
- Clinical Context: Always correlate findings with patient history, physical exam (e.g., pulses, jugular venous pressure), and imaging (e.g., echocardiography).
Disclaimer: owerl is not a doctor; please consult one. Don’t share information that can identify you.
Leave a Reply