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Overview

This note walks through how to identify common murmurs the way the exam tests them: timing (systolic vs diastolic) + location (base vs apex) + character (opening snap, holosystolic, crescendo–decrescendo, decrescendo) + response to maneuvers (squat/leg raise vs Valsalva). Diagnosis is confirmed with echocardiogram, and treatment patterns largely split into valve intervention (most lesions) versus beta blockade + avoid dehydration (hypertrophic cardiomyopathy and mitral valve prolapse), with balloon valvotomy/valvuloplasty emphasized for mitral stenosis.

Key takeaways

• Work up: any diastolic murmur or systolic grade ≥ 3 → echocardiogram.
• Mitral murmurs are heard best at the apex; aortic murmurs at the base (right sternal border).
• Mitral stenosis: diastolic + opening snap + rumbling at apex; classically rheumatic; treat with balloon valvotomy/valvuloplasty (then possible replacement).
• Aortic regurgitation (insufficiency): diastolic murmur at the base; acute causes can present with cardiogenic shock + flash pulmonary edema → emergent replacement.
• Aortic stenosis: systolic crescendo–decrescendo at base; typically elderly with calcification/atherosclerosis; treat with replacement (balloon not effective for calcified valve).
• Mitral regurgitation (insufficiency): holosystolic, blowing at apex (often radiates to axilla per PDF); acute = shock/flash edema → emergent replacement.
• Maneuvers:
  • For MS / MR / AS / AR: more preload → louder murmur (squat/leg raise worsen; Valsalva improves).
  • For hypertrophic cardiomyopathy and mitral valve prolapse: more preload → softer murmur (squat/leg raise improve; Valsalva worsens).
• Exam trap: hypertrophic cardiomyopathy can sound like aortic stenosis; distinguish via age/history and maneuver response.

Common traps / misunderstandings

• Confusing mitral stenosis (diastolic + opening snap) with aortic regurgitation (diastolic at base, no opening snap).
• Calling every harsh systolic murmur “aortic stenosis” without checking maneuver response (hypertrophic cardiomyopathy is the classic distractor).
• Forgetting that acute regurgitation (aortic or mitral) can present as cardiogenic shock + flash pulmonary edema and needs immediate valve intervention.
• “Not stated”: additional pitfalls beyond the above are not explicitly listed.

Murmurs: Basics, Grading, and When to Work Up

What murmurs represent

• Murmurs occur from turbulent flow across a stenotic or regurgitant valve.

Grading (1–6)

• Grade 1: S1/S2 louder than murmur.
• Grade 2: S1/S2 equal to murmur.
• Grade 3: murmur louder than S1/S2.
• Grade 4: palpable thrill.
• Grade 5: very loud; can hear with stethoscope partially off chest.
• Grade 6: heard without a stethoscope.

When to investigate

• Investigate:
  • Any diastolic murmur, OR
  • Systolic murmur grade ≥ 3, OR
  • Symptomatic murmur.
• Confirmatory diagnosis: echocardiogram.

Maneuvers: The Exam Pattern

Principle sets

Group A — “More blood in the heart → more murmur”

• Mitral stenosis
• Mitral regurgitation
• Aortic stenosis
• Aortic regurgitation
  Effect of maneuvers
• Squat / leg raise (↑ venous return / preload): worsens
• Valsalva (↓ venous return / preload): improves

Group B — “More blood in the heart → less murmur”

• Hypertrophic cardiomyopathy (with left ventricular outflow tract obstruction physiology)
• Mitral valve prolapse
  Effect of maneuvers
• Squat / leg raise: improves
• Valsalva: worsens

Lesions One-by-One (how the exam wants it)

Mitral stenosis

Core idea

• Obstruction to flow across the mitral valve during diastole → blood backs up into left atrium and lungs.

Mechanism / reasoning chain

1. Mitral valve becomes thickened/stenotic (classically rheumatic).
2. ↓ forward flow into left ventricle during diastole.
3. ↑ left atrial pressure → left atrial dilation.
4. Back pressure into lungs → pulmonary congestion / heart failure symptoms.
5. Atrial stretch → risk of atrial fibrillation.

Clinical implications

• Typical patient: younger (often 20s–30s).
• Symptoms: dyspnea on exertion, paroxysmal nocturnal dyspnea, crackles, possible atrial fibrillation.

Auscultation

• Diastolic murmur, heard best at apex (5th intercostal space, midclavicular line).
• Described as rumbling diastolic murmur with an opening snap.
  • Opening snap is the “giveaway.”

Treatment

• Emphasized therapy: balloon valvotomy / valvuloplasty (rheumatic, not calcified).
• Valve replacement exists but delayed when possible (young patients; sternotomy concern).

Aortic regurgitation (aortic insufficiency)

Core idea

• Floppy aortic valve allows blood to flow back into left ventricle during diastole → volume overload → heart failure; can be acute and catastrophic.

Mechanism / reasoning chain

1. Aortic valve fails to close → regurgitation in diastole.
2. Left ventricle fills normally via mitral valve plus regurgitant aortic flow.
3. Volume overload → dilated heart → heart failure.
4. Acute loss of valve function → poor forward flow → cardiogenic shock and flash pulmonary edema.

Clinical implications

• Causes described: infection (endocarditis), infarction, and proximal aortic dissection (tearing chest pain may appear with dissection).
• Presentation:
  • Acute: cardiogenic shock + flash pulmonary edema (± tearing pain if dissection).
  • Chronic: heart failure symptoms (dyspnea on exertion, paroxysmal nocturnal dyspnea, crackles).
• Chest pain can occur because coronary filling is in diastole; vignette “chest pain” alone is not decisive—acuity matters.

Auscultation

• Diastolic murmur.
• Heard best at the base: 2nd intercostal space, right sternal border.
• Described as decrescendo in the PDF; transcript emphasizes “rumbling” without opening snap. If phrasing differs, prioritize timing + location.

Treatment

• Valve replacement:
  • Emergent if acute.
  • Urgent to elective if chronic, generally before angina or heart failure symptoms.

Aortic stenosis

Core idea

• Obstruction to flow out of the left ventricle during systole due to calcification/atherosclerosis (accelerated by bicuspid valve) → pressure overload → hypertrophy and failure.

Mechanism / reasoning chain

1. Valve becomes stiff/calcified → does not open well.
2. Left ventricle pushes against high resistance (↑ afterload).
3. Compensatory changes occur and eventual heart failure.

Clinical implications

• Typical patient: elderly men with atherosclerotic disease.
• Presentations emphasized: angina, syncope, and heart failure symptoms.

Auscultation

• Systolic murmur.
• Heard best at base (right sternal border); PDF notes radiation to carotids.
• Character: crescendo–decrescendo.

Treatment

• Valve replacement (balloon valvotomy not effective for calcified stenosis).
• CABG consideration is raised because of coronary ostia relationship during aortic valve surgery.

Memory hook (from transcript)

• “AS = atherosclerosis = aortic stenosis (AS)”.

Mitral regurgitation (mitral insufficiency)

Core idea

• Mitral leaflets do not coapt → blood regurgitates from left ventricle to left atrium during systole → atrial stretch + pulmonary congestion; acute forms can cause shock.

Mechanism / reasoning chain

1. In systole, blood exits left ventricle into aorta and leaks back into left atrium.
2. ↑ left atrial pressure → atrial dilation/stretch.
3. Back pressure into lungs → pulmonary congestion / heart failure.
4. Acute destructive causes → sudden severe regurgitation → cardiogenic shock + flash pulmonary edema.

Clinical implications

• Causes described: infection or infarction (PDF expands with papillary muscle/chordae issues; include as supportive detail).
• Presentation:
  • Acute: cardiogenic shock + flash pulmonary edema → emergent intervention.
  • Chronic: dyspnea/fatigue; may develop atrial fibrillation from atrial stretch.

Auscultation

• Heard best at apex.
• Systolic; described as high-pitched, blowing.
• Key descriptor: holosystolic (murmur spans all of systole; S1/S2 may be obscured).
• PDF adds typical radiation to axilla.

Treatment

• Ultimately valve replacement:
  • Emerent if acute and devastating.
  • Delayed if chronic, but replace before CHF / atrial fibrillation “set in.”

Hypertrophic cardiomyopathy

Core idea

• Septal hypertrophy narrows the left ventricular outflow tract → systolic murmur that can mimic aortic stenosis, but maneuver response is opposite.

Mechanism / reasoning chain

1. Septum hypertrophies and obstructs outflow tract.
2. Smaller ventricular cavity (especially with dehydration) → worse obstruction.
3. Worse obstruction → symptoms and risk of sudden death.
4. Increasing preload expands the ventricle → less obstruction → softer murmur.

Clinical implications

• Typical scenario: young athlete with exertional symptoms (shortness of breath or syncope).
• Family history of sudden cardiac death can be a clue.

Auscultation

• Systolic murmur that can sound like aortic stenosis.
• Key differentiator: squat/leg raise improves, Valsalva worsens.

Treatment (as stated)

• Avoid dehydration (maintain preload).
• Beta blockade (slow heart rate to increase diastolic filling time).
• Strong caution is stated about dehydration and activities that increase heart rate.

Mitral valve prolapse

Core idea

• Congenital leaflet abnormality: leaflets “too big” → prolapse and regurgitation-like murmur, but gets better with more preload (opposite of typical regurgitation lesions).

Mechanism / reasoning chain

1. Leaflets do not close optimally; they “pooch” into atrium.
2. During systole, can resemble mitral regurgitation.
3. Increasing ventricular volume stretches the annulus and improves leaflet coaptation.
4. Therefore, increased preload → less regurgitation/murmur.

Clinical implications

• Described as usually congenital, often in young women.
• Diagnosed definitively by echocardiogram.

Auscultation + maneuvers

• Sounds like mitral regurgitation, but:
  • Improves with squat/leg raise
  • Worsens with Valsalva

Treatment

• Avoid dehydration
• Beta blockade
• Does not require valve replacement.

Visuals / Tables / Algorithms

Murmur identification map (timing + location)

Summary table (location + maneuvers + path + treatment)

Decision flow (exam style)

1) Is it systolic or diastolic?
   - Diastolic → workup + echo → identify location:
       • Apex + opening snap → Mitral stenosis → balloon valvotomy/valvuloplasty
       • Base (right sternal border), no opening snap → Aortic regurgitation → replace (emergent if acute)
   - Systolic → identify location + quality:
       • Base + crescendo–decrescendo + elderly/atherosclerosis → Aortic stenosis → replace
       • Apex + holosystolic blowing → Mitral regurgitation → replace (emergent if acute)
       • Sounds like AS but young/athlete or family history → try maneuvers:
            - Squat/leg raise improves → Hypertrophic cardiomyopathy
            - Squat/leg raise improves + young woman + MR-like → Mitral valve prolapse
2) Maneuver cross-check:
   - Typical valve lesions (MS/MR/AS/AR): squat/leg raise worse; Valsalva better
   - HCM/MVP: squat/leg raise better; Valsalva worse

Memory Hooks

• AS = atherosclerosis = aortic stenosis (AS) (transcript).

Exam / UWorld triggers

• “Diastolic murmur” → always needs workup/echo.
• “Opening snap + diastolic rumble at apex” → mitral stenosis (rheumatic, younger).
• “Holosystolic blowing at apex (± to axilla)” → mitral regurgitation.
• “Crescendo–decrescendo at base” in an older patient → aortic stenosis.
• “Murmur like AS but young athlete, exertional syncope/shortness of breath, family sudden death” → hypertrophic cardiomyopathy.
• Maneuver trap:
  • “Leg raise/squat improves murmur” → think hypertrophic cardiomyopathy or mitral valve prolapse, not the typical four.

End-of-note recap

Ultra-short summary (≤8 lines)

• Identify murmur by timing + location + character, then use maneuvers as the tie-breaker.
• Work up any diastolic or systolic grade ≥ 3 murmur with echocardiogram.
• MS: diastolic + opening snap at apex → balloon valvotomy/valvuloplasty.
• AR: diastolic at base → replacement (emergent if acute).
• AS: systolic crescendo–decrescendo at base → replacement.
• MR: holosystolic blowing at apex → replacement (emergent if acute).
• HCM/MVP: improve with squat/leg raise; treat with beta blockade + avoid dehydration.

Checklist (what to remember)

• Apex = mitral; base (right sternal border) = aortic
• Diastolic always matters (workup)
• Opening snap → mitral stenosis
• Holosystolic blowing → mitral regurgitation
• Crescendo–decrescendo at base → aortic stenosis
• Squat/leg raise improves → hypertrophic cardiomyopathy or mitral valve prolapse