How should I assess a systolic murmur?

How to Assess a Systolic Murmur

Begin with systematic cardiac auscultation to characterize the murmur's timing, intensity (grade 1-6), configuration (crescendo, decrescendo, crescendo-decrescendo, or plateau), location, radiation, and pitch, then perform dynamic maneuvers to differentiate pathologic from innocent murmurs. 1

Initial Auscultatory Assessment

Characterize the Murmur Systematically

• Timing within systole: Determine if the murmur is holosystolic (pansystolic), midsystolic (ejection), or late systolic, as this fundamentally guides your diagnostic approach 1
• Intensity grading: Use the 1-6 scale, where grade 1 is barely audible, grade 3 is moderately loud, and grade 6 is audible with stethoscope off the chest 2
• Configuration: Identify whether the murmur is crescendo-decrescendo (diamond-shaped, typical of ejection murmurs), plateau (holosystolic), or crescendo (late systolic) 1
• Location of maximal intensity: Listen at the aortic area (right upper sternal border), pulmonic area (left upper sternal border), left sternal border, and apex 3
• Radiation pattern: Note if the murmur radiates to the neck (suggests aortic stenosis), back (suggests coarctation), or axilla (suggests mitral regurgitation) 1

Assess Associated Cardiac Findings

• Second heart sound (S2): Evaluate for normal splitting with respiration, fixed splitting (suggests atrial septal defect), paradoxical splitting, or diminished/absent A2 component (suggests severe aortic stenosis) 1, 4
• Additional heart sounds: Listen for S3 gallop (suggests heart failure or severe regurgitation), S4 gallop (suggests ventricular hypertrophy), or ejection clicks (suggest bicuspid aortic valve or pulmonic stenosis) 1
• Apical impulse: Palpate for displacement or hyperdynamic quality, which suggests ventricular enlargement or volume overload 5

Dynamic Cardiac Auscultation Maneuvers

Perform physiologic maneuvers to distinguish pathologic from innocent murmurs and identify specific lesions. 1, 3

Valsalva Maneuver

• Most murmurs decrease with Valsalva due to reduced venous return 3
• Hypertrophic cardiomyopathy murmur increases markedly during strain phase—this is a critical red flag requiring immediate echocardiography 1, 3
• Mitral valve prolapse murmur lengthens and becomes louder with Valsalva 3

Positional Changes

• Standing from squatting: Murmurs of hypertrophic cardiomyopathy and mitral valve prolapse become louder when standing and decrease when squatting 1, 3
• Innocent murmurs do not increase with standing 1

Sustained Handgrip Exercise

• Increases afterload: Murmurs of mitral regurgitation, ventricular septal defect, and aortic regurgitation become louder with sustained handgrip 1, 3
• Aortic stenosis murmur decreases with handgrip 3

Respiratory Variation

• Right-sided murmurs increase with inspiration (Carvallo's sign for tricuspid regurgitation) 3
• Left-sided murmurs increase with expiration 3

Post-Premature Ventricular Contraction

• Aortic stenosis murmur increases in the beat following a PVC due to increased stroke volume 1
• Mitral regurgitation and ventricular septal defect murmurs do not increase after a PVC—this helps distinguish them from aortic stenosis 1

Classification-Based Assessment Algorithm

Holosystolic (Pansystolic) Murmurs

All holosystolic murmurs require echocardiography regardless of intensity or symptoms. 1, 5

• These murmurs extend from S1 through S2 and indicate flow between chambers with widely different pressures throughout systole 1
• Primary causes: Mitral regurgitation, tricuspid regurgitation, or ventricular septal defect 1, 5
• Critical pitfall: Do not dismiss holosystolic murmurs based on low intensity alone—even grade 2/6 holosystolic murmurs can represent severe chronic mitral regurgitation 5

Midsystolic (Ejection) Murmurs

The approach depends on murmur grade, associated findings, and patient characteristics. 1

• Grade 3 or louder: Requires echocardiography in all asymptomatic patients 1
• Grade 1-2 in young, asymptomatic patients: May be innocent if all of the following are present:
  • Heard at left sternal border 1
  • Normal S2 intensity and splitting 1
  • No other abnormal cardiac sounds 1
  • No increase with Valsalva or standing 1
  • No symptoms or abnormal physical findings 1
• Echocardiography is NOT recommended for grade 2 or softer midsystolic murmurs identified as innocent by an experienced observer 1
• Common innocent causes: High-output states (anemia, pregnancy, thyrotoxicosis, fever) 1
• Pathologic causes: Aortic stenosis, pulmonic stenosis, hypertrophic cardiomyopathy 1

Late Systolic Murmurs

All late systolic murmurs require echocardiography. 1

• These murmurs begin in mid-to-late systole and extend to S2 3
• Primary cause: Mitral valve prolapse with regurgitation 1
• Often preceded by a mid-systolic click 1

Mandatory Echocardiography Indications

Obtain echocardiography immediately for any of the following, regardless of murmur intensity: 1, 5

Based on Murmur Characteristics

• All diastolic murmurs (virtually always pathologic) 1
• All continuous murmurs (except innocent venous hums and mammary souffles) 1, 5
• All holosystolic murmurs 1, 5
• All late systolic murmurs 1
• Grade 3 or louder midsystolic murmurs 1
• Murmurs with ejection clicks 1
• Murmurs radiating to neck or back 1

Based on Associated Symptoms

• Heart failure symptoms (dyspnea, orthopnea, edema) 1, 5
• Syncope (suggests severe aortic stenosis or hypertrophic cardiomyopathy) 1, 5
• Angina (indicates hemodynamically significant valve disease) 5
• Thromboembolism 1, 5
• Signs of infective endocarditis (fever, new murmur, embolic phenomena) 1, 5

Based on Abnormal Physical Findings

• Abnormal S2 (fixed splitting, diminished/absent A2, paradoxical splitting) 1
• S3 or S4 gallop 1
• Displaced or hyperdynamic apical impulse 5
• Abnormal peripheral pulses (parvus et tardus, bounding pulses) 4

Based on Ancillary Testing

• Abnormal ECG (ventricular hypertrophy, prior infarction) 1
• Abnormal chest X-ray (cardiomegaly, pulmonary congestion, valvular calcification) 1

Adjunctive Testing

ECG and Chest X-Ray

• Not routinely recommended for asymptomatic patients with grade 2 or softer midsystolic murmurs at the left sternal border, particularly in younger patients 1
• Obtain if immediately available but do not delay echocardiography 5
• Proceed to echocardiography if ECG shows ventricular hypertrophy or prior infarction, or if chest X-ray shows abnormal cardiac chamber size or pulmonary congestion 1

Cardiac Catheterization

• Not necessary for most patients with cardiac murmurs and normal or diagnostic echocardiograms 1
• Consider when there is discrepancy between echocardiographic and clinical findings 1

Critical Pitfalls to Avoid

• Never dismiss an ejection systolic murmur in a patient with exertional syncope as "innocent"—this combination requires immediate echocardiography until structural heart disease is excluded 3
• Do not rely on murmur intensity alone to exclude severe disease—severe aortic stenosis can present with a soft murmur when left ventricular ejection fraction is severely reduced 6
• Recognize that aortic regurgitation commonly presents with a systolic murmur rather than the classic diastolic murmur, especially when detected by non-cardiologists 7
• Be aware that combined valvular lesions (especially aortic and mitral disease) are commonly missed on clinical examination, with sensitivity only 55% for detecting combined lesions 6
• Remember that trivial valvular regurgitation may be detected by echocardiography in many normal patients with no audible murmur—interpret echo findings in clinical context 1
• In high-output states (anemia, pregnancy, thyrotoxicosis), functional murmurs typically resolve with treatment of the underlying condition—reassess after correction 1, 4