What is the proper technique for assessing heart sounds using a stethoscope in patients with varying medical histories and demographics?

Proper Technique for Assessing Heart Sounds with a Stethoscope

Systematic Auscultation Approach

Cardiac auscultation should follow a structured sequence examining all four primary valve areas (aortic, pulmonic, tricuspid, and mitral) using both the diaphragm and bell of the stethoscope, with specific attention to timing, location, radiation, and response to physiological maneuvers. 1

Essential Components of the Examination

Patient Positioning:

• Begin with the patient supine, then assess in left lateral decubitus position (enhances S3, S4, and mitral sounds) and sitting upright leaning forward (enhances aortic regurgitation murmurs) 1
• Document patient position when recording findings, as blood pressure and heart sounds vary with position 1

Systematic Assessment Sequence:

• Heart rate and rhythm: Document whether regular or irregular, obtained from physical examination or ECG tracing 1
• First heart sound (S1): Note intensity and any splitting 2
• Second heart sound (S2): Assess intensity, physiologic splitting (widens with inspiration, narrows with expiration), and any abnormal splitting patterns 1, 2
• Third heart sound (S3): Mid-diastolic sound indicating volume overload or heart failure; present in most normal pregnancies but pathologic in other adults 1, 2
• Fourth heart sound (S4): Late-diastolic sound indicating decreased ventricular compliance 1
• Murmurs: Document timing (systolic vs. diastolic), location, intensity (grade 1-6 for systolic, 1-4 for diastolic), quality (harsh, blowing, ejection), and radiation 1

Dynamic Cardiac Auscultation Maneuvers

Dynamic maneuvers are essential for distinguishing pathologic from innocent murmurs and identifying specific cardiac conditions. 1, 3

Key Physiological Maneuvers

Valsalva Maneuver:

• Most murmurs decrease in intensity 3
• Hypertrophic cardiomyopathy murmur increases (65% sensitivity, 96% specificity) 3
• Mitral valve prolapse murmur also increases 1

Position Changes (Standing from Squatting):

• Hypertrophic cardiomyopathy murmur increases (95% sensitivity, 84% specificity for HCM) 3
• Mitral valve prolapse murmur increases 1
• Most other murmurs decrease 1

Sustained Handgrip Exercise:

• Mitral regurgitation and ventricular septal defect murmurs increase (68% sensitivity, 92% specificity) 3
• Aortic stenosis murmur decreases 3

Transient Arterial Occlusion:

• Mitral regurgitation murmur increases in intensity 1

Post-Premature Ventricular Contraction or Long R-R Interval:

• Aortic stenosis murmur increases 1
• Mitral regurgitation and ventricular septal defect murmurs do not increase 1

Population-Specific Considerations

Pregnancy

Normal cardiovascular findings in pregnancy include:

• Louder S1 with prominent splitting due to 50% increase in blood volume 2
• Physiologically split S2 (may appear fixed in later pregnancy) 2
• S3 present in most pregnant patients 2
• Soft grade 1-2 midsystolic murmur at mid to upper left sternal border 2
• Continuous murmurs (venous hum or mammary souffle) 2
• Hyperkinetic precordial impulse 2

Concerning findings requiring evaluation:

• Any diastolic murmur (unusual in normal pregnancy) 2
• Grade 3 or greater systolic murmur 1, 2

Children and Young Adults

Grade 1-2 midsystolic murmurs in asymptomatic children and young adults with otherwise normal cardiac examination typically represent innocent murmurs and do not require extensive workup. 1

Characteristics of innocent murmurs:

• Grade 1-2 intensity at left sternal border 1, 3
• Systolic ejection pattern 1, 3
• Normal S2 intensity and physiologic splitting 1, 3
• No other abnormal cardiac sounds 1, 3
• No increase with Valsalva or standing from squatting 1
• Common in high-output states (anemia, pregnancy, thyrotoxicosis, arteriovenous fistula) 1, 3

Indications for Echocardiography

Echocardiography is mandatory for:

• All diastolic murmurs (except cervical venous hum or mammary souffle in pregnancy) 1, 3
• Grade 3 or greater midsystolic murmurs 1, 3
• All holosystolic or late systolic murmurs (apical or left sternal edge) 1, 3
• Systolic murmurs with abnormal dynamic auscultation suggesting hypertrophic cardiomyopathy or mitral valve prolapse 1
• Any murmur with symptoms (heart failure, syncope, myocardial ischemia, chest pain, dyspnea, thromboembolism, or signs of endocarditis) 1, 3
• Grade 1-2 systolic murmurs with other abnormal findings (widely split S2, systolic ejection sounds, abnormal S3/S4 in non-pregnant adults) 1

Echocardiography is NOT indicated for:

• Typically innocent murmurs (grade 1-2 midsystolic) in asymptomatic patients without other cardiac findings 1

Critical Pitfalls to Avoid

Do not rely solely on stethoscope examination to exclude significant valvular disease - optimal auscultation by well-trained examiners reduces unnecessary testing, but echocardiography remains the definitive diagnostic tool when clinical suspicion exists 1

Recognize that trivial valvular regurgitation detected by echocardiography is common in normal patients - do not over-interpret minimal regurgitation found incidentally, especially when evaluating isolated murmurs in asymptomatic patients 1

Always assess S2 splitting pattern - fixed splitting suggests atrial septal defect, reversed splitting suggests left bundle branch block or severe aortic stenosis, and absent A2 suggests severe aortic stenosis 3

Document specific murmur characteristics systematically - timing, location, radiation, intensity, quality, and response to maneuvers are essential for accurate diagnosis and determining need for further evaluation 1