Heart murmurs feel like chaos until you force them into a repeatable decision tree. On exams (and in real life), you’re not being tested on poetry—you’re being tested on whether you can hear timing + location + radiation + maneuvers and snap to the correct valve lesion.
The Step-by-Step Murmur Flowchart (USMLE-style)
Step 1: When does it happen?
Use timing to cut your options in half.
- Systolic (between S1 → S2): think AS, MR, TR, VSD, HCM
- Diastolic (between S2 → S1): think AR, MS, TS
- Continuous: think PDA (machine-like)
Rule of thumb: Diastolic murmurs are always pathologic.
Step 2: What does it sound like (shape + quality)?
- Crescendo–decrescendo (ejection): outflow obstruction (AS, HCM)
- Holosystolic (pan-systolic, plateau): regurg/shunt (MR, TR, VSD)
- Early diastolic decrescendo: AR
- Mid-diastolic rumble + opening snap: MS
Step 3: Where is it loudest? (Listen at the “home base”)
Know these cold:
| Valve/Lesion | Best heard at | Classic radiation |
|---|---|---|
| Aortic stenosis (AS) | RUSB (2nd ICS, right) | To carotids |
| Aortic regurg (AR) | LSB (3rd ICS) | Toward apex; can be along LSB |
| Mitral regurg (MR) | Apex | To axilla |
| Mitral stenosis (MS) | Apex (bell) | Localized; little radiation |
| Tricuspid regurg (TR) | LLSB | To right sternal border |
| Pulmonic stenosis | LUSB | To left neck/shoulder |
| VSD | LLSB | Often thrill |
| PDA | Left infraclavicular | “Machine-like” to back |
RUSB = right upper sternal border; LUSB = left upper; LLSB = left lower; ICS = intercostal space.
Step 4: What do maneuvers do? (The test-writer’s favorite)
Maneuvers change preload, afterload, or venous return, changing murmur intensity.
Quick maneuver table (high-yield)
| Maneuver | Hemodynamic change | Murmurs that get louder | Murmurs that get softer |
|---|---|---|---|
| Inspiration | ↑ venous return to right heart | TR, TS, pulmonic murmurs | Most left-sided |
| Expiration | ↑ return to left heart | MR, AR, AS | Right-sided |
| Handgrip | ↑ afterload | MR, AR, VSD | AS, HCM |
| Squat / leg raise | ↑ preload, ↑ afterload | AS (usually ↑), MR (often ↑) | HCM (↓), MVP click moves later |
| Valsalva / standing | ↓ preload | HCM (↑), MVP click moves earlier | AS (↓), most others |
Board classic: HCM gets louder with Valsalva/standing (less preload → smaller LV cavity → worse obstruction).
MVP: decreased preload makes the click happen earlier and murmur longer.
The Visual/Mnemonic Device: “TIMING → PLACE → PUSH/PULL”
Think of it like a 3-box flow:
1) TIMING
- Systolic: AS, MR, TR, VSD, HCM
- Diastolic: AR, MS, TS
- Continuous: PDA
2) PLACE (home base)
- RUSB: AS
- LSB: AR (and HCM often along LSB)
- Apex: MR/MS
- LLSB: TR/VSD
3) PUSH/PULL (maneuvers)
- Handgrip pushes afterload up → MR/AR/VSD louder; AS/HCM softer
- Valsalva pulls preload down → HCM/MVP louder (or earlier click)
You can literally sketch this on scrap paper in 10 seconds.
Quick-Hit One-Liners (Shareable + exam-ready)
Aortic Stenosis (AS)
- Murmur: systolic crescendo–decrescendo at RUSB, radiates to carotids
- One-liner: “Tight aortic valve = harsh ejection murmur to the neck + pulsus parvus et tardus.”
- Associations: elderly calcific disease; younger with bicuspid aortic valve
- Extra high-yield: can cause syncope, angina, dyspnea (SAD)
Aortic Regurgitation (AR)
- Murmur: early diastolic blowing decrescendo at LSB
- One-liner: “Leaky aorta = wide pulse pressure + blowing diastolic murmur.”
- Associations: endocarditis, aortic root dilation (Marfan), rheumatic disease
- Extra high-yield: bounding pulses; may hear Austin Flint murmur (functional MS-like rumble)
Mitral Regurgitation (MR)
- Murmur: holosystolic at apex, radiates to axilla
- One-liner: “Leaky mitral valve = pan-systolic at apex to axilla, louder with handgrip.”
- Associations: ischemic papillary muscle dysfunction/rupture (post-MI), MVP, dilated cardiomyopathy
Mitral Stenosis (MS)
- Murmur: opening snap + mid-diastolic rumble at apex (use bell)
- One-liner: “Rheumatic MS = opening snap + diastolic rumble and left atrial enlargement.”
- Associations: classically rheumatic fever
- Extra high-yield: can cause atrial fibrillation and hoarseness (Ortner syndrome from LA enlargement)
Tricuspid Regurgitation (TR)
- Murmur: holosystolic at LLSB, louder with inspiration (Carvallo sign)
- One-liner: “Right-sided regurg gets louder when you breathe in.”
- Associations: endocarditis in IV drug use, pulmonary HTN/right dilation
- Extra high-yield: prominent v waves in JVP
Hypertrophic Cardiomyopathy (HCM)
- Murmur: systolic crescendo–decrescendo (often LSB), louder with Valsalva/standing, softer with squat
- One-liner: “HCM = obstruction worse when LV is underfilled.”
- Associations: AD sarcomere mutations; young athlete syncope/sudden death
- Extra high-yield: harsh systolic murmur + possible S4 (stiff ventricle)
Mitral Valve Prolapse (MVP)
- Murmur: mid-systolic click ± late systolic murmur
- One-liner: “MVP click comes earlier when preload drops (standing/Valsalva).”
- Associations: myxomatous degeneration; can be seen with Marfan/Ehlers-Danlos
- Extra high-yield: often benign, but can lead to MR; palpitations/anxiety-type presentation
Ventricular Septal Defect (VSD)
- Murmur: harsh holosystolic at LLSB with thrill
- One-liner: “VSD = loud LLSB holosystolic murmur; small defects can be louder.”
- Extra high-yield: large VSD → pulmonary HTN → Eisenmenger (late)
Patent Ductus Arteriosus (PDA)
- Murmur: continuous machine-like murmur (left infraclavicular)
- One-liner: “PDA = continuous flow across the duct → continuous murmur.”
- Associations: prematurity, congenital rubella
- Extra high-yield: treat with indomethacin (closes); keep open with PGE1 in ductal-dependent lesions
Mini Drill: If you only memorize 6 maneuver effects
- Inspiration ↑ right murmurs (TR)
- Handgrip ↑ MR/AR/VSD
- Handgrip ↓ HCM/AS
- Valsalva/standing ↑ HCM
- Squat ↓ HCM, delays MVP click
- Diastolic = pathologic (always investigate)
Lightning “Spot Diagnosis” Prompts (How questions are written)
- “Harsh systolic murmur radiating to carotids + slow-rising pulse” → AS
- “Holosystolic at apex to axilla, louder with handgrip” → MR
- “Opening snap + diastolic rumble, history of rheumatic fever” → MS
- “Blowing early diastolic + wide pulse pressure” → AR
- “Systolic murmur louder with Valsalva” → HCM
- “Holosystolic at LLSB louder with inspiration” → TR
- “Continuous machine-like murmur” → PDA