Here's a quick-fire memory system for cardiac murmurs - built around how NBME/Step actually tests them.
The Master Cheat Sheet: Cardiac Murmurs
1. LOCATION LANDMARKS (memorize these 4 anchor points)
| Area | Location | Mnemonic |
|---|
| Aortic | Right 2nd ICS | "Aorta = Right 2" → AR2 |
| Pulmonic | Left 2nd ICS | "Pulmonic = Left 2" → PL2 |
| Tricuspid | Left 4th/5th ICS (sternal border) | "Tri = 4" (4 letters in "Tri") |
| Mitral | Left 5th ICS midclavicular line | "Mitral = Apex" → MA (Mitral Apex) |
Memory trick: "All Patients Take Medicine" = Aortic, Pulmonic, Tricuspid, Mitral (going counterclockwise on the chest)
2. SYSTOLIC vs DIASTOLIC - THE GOLDEN RULE
"PASS" = Pulmonic/Aortic Stenosis are Systolic
"MR T" = Mitral Regurg + Tricuspid Regurg are Systolic
So in systole (heart contracts, blood goes OUT):
- Outflow valves (Aortic, Pulmonic) STENOSIS = obstructed ejection → systolic murmur
- Inlet valves (Mitral, Tricuspid) REGURGITATION = blood leaks back → systolic murmur
Flip everything for diastole:
- AR/PR (aortic/pulmonic regurg) = diastolic
- MS/TS (mitral/tricuspid stenosis) = diastolic
3. THE BIG 8 - HIGH YIELD TABLE
| Murmur | Timing | Location | Radiation | Quality | Key Trick |
|---|
| Aortic Stenosis (AS) | Systolic (crescendo-decrescendo) | Right 2nd ICS | To carotids | Harsh | "Old man, carotids, syncope/angina/HF" |
| Aortic Regurg (AR) | Early diastolic (decrescendo) | Left sternal border | - | Blowing | Lean forward + hold breath = louder |
| Mitral Stenosis (MS) | Mid-diastolic | Apex | - | Rumbling + opening snap | Rheumatic fever, afib, loud S1 |
| Mitral Regurg (MR) | Holosystolic | Apex | To axilla | Blowing | "Axilla" = MR. Radiation = axilla |
| MVP | Late systolic (after click) | Apex | - | - | Click then murmur. Valsalva = earlier click |
| Tricuspid Regurg (TR) | Holosystolic | Left 4th ICS | - | Blowing | Increases with inspiration (Carvallo's sign) |
| Pulmonic Stenosis (PS) | Systolic (crescendo-decrescendo) | Left 2nd ICS | - | Harsh | Loud P2 is absent |
| HCM | Systolic (mid) | Left sternal border | - | Harsh | Valsalva/standing LOUDER, squatting SOFTER |
4. THE TWO MANEUVERS NBME LOVES - MASTER THESE
NBME absolutely hammers maneuvers. Learn this table cold:
| Maneuver | Preload | What happens |
|---|
| Valsalva / Standing | ↓ preload | Most murmurs ↓ EXCEPT HCM and MVP (both get louder) |
| Squatting / Leg raise | ↑ preload | Most murmurs ↑ EXCEPT HCM and MVP (both get softer) |
| Inspiration | ↑ right heart filling | Right-sided murmurs louder (TR, PS, TS) = Carvallo's sign |
| Expiration | ↑ left heart filling | Left-sided murmurs louder (AS, MR, MS, AR) |
| Handgrip | ↑ afterload | AR, MR, VSD louder. AS softer |
Memory trick for HCM/MVP:
"HCM and MVP are divas - they get LOUDER when the heart is EMPTIER (less preload = more obstruction/prolapse)"
5. HOW NBME ASKS - COMMON QUESTION STEMS
Pattern 1 - "The murmur changes with..."
→ They describe a maneuver and ask what murmur. Use the table above.
Pattern 2 - "Where is this best heard?"
→ They describe quality + timing. Map to the Big 8 table.
Pattern 3 - "Young athlete collapses"
→ Answer = HCM (not AS in young people). Murmur louder with Valsalva.
Pattern 4 - "Elderly with syncope/chest pain on exertion"
→ Answer = AS. Crescendo-decrescendo at right 2nd ICS, radiates to carotids. Pulsus parvus et tardus.
Pattern 5 - "Rheumatic fever history + atrial fibrillation"
→ Answer = MS. Opening snap + mid-diastolic rumble at apex.
Pattern 6 - "IV drug user or right heart involvement"
→ Answer = TR. Increases with inspiration.
Pattern 7 - "Holosystolic murmur radiating to axilla"
→ Answer = MR. Always.
6. THE 60-SECOND DECISION TREE (exam strategy)
Step 1: TIMING?
Systolic → AS, PS, MR, TR, HCM, MVP, VSD
Diastolic → AR, PR, MS, TS
Step 2: LOCATION?
Right 2nd ICS → AS
Left 2nd ICS → PS or AR (if diastolic)
Apex → MR or MS
Left sternal border → HCM, TR, AR, VSD
Step 3: RADIATION / SPECIAL FEATURE?
Carotids → AS
Axilla → MR
Opening snap → MS
Click preceding → MVP
Inspiration increases → right-sided (TR, TS, PS)
Step 4: MANEUVER given?
Valsalva louder → HCM or MVP (only exceptions!)
Handgrip louder → MR, AR, VSD
7. BONUS MEMORY HOOKS
- "MS = Midlife Stenosis" - always rheumatic, always mitral, always rumble
- "AR = Aortic Runs away" - decrescendo, blows right after S2, marfan/syphilis/endocarditis
- "MR = Mitral Runs to axilla" - radiation to axilla, holosystolic
- "HCM hates squatting" - squatting fills the heart, HCM disappears
- "AS = old, slow, sadistic" - pulsus parvus et tardus, syncope, angina, dyspnea (SAD triad)
These 7 components cover ~95% of how Step 1/2 and NBME shelf exams test murmurs. The maneuver table is the single most tested concept - if you nail that, you'll never miss a murmur question again.