Nursing care
Heart murmurs for nurses: how murmurs are graded, timed and remembered
Written and reviewed by Kevin Patel, MSN, RN, CCRN · 5 min read · Updated November 2026
Short answer
Heart murmurs are graded by loudness from 1 to 6: grade 1 is barely audible, grade 4 adds a palpable thrill, and grade 6 is heard with the stethoscope just off the chest. Nurses also note timing (systolic or diastolic), location and radiation. Diastolic murmurs are always abnormal, and any new murmur is reported to the provider.
Murmur grades 1 to 6 and what each grade tells the nurse
A murmur is a blowing, whooshing or rasping sound made by turbulent flow through the heart. MSD Manuals grades systolic murmurs on six levels by intensity; diastolic murmurs use a shorter 1 to 4 scale.
| Grade | What the listener notices | Bedside meaning |
|---|---|---|
| 1 | Barely audible, may come and go | Easy to miss; a quiet room and careful listening needed |
| 2 | Soft but easy to hear | Audible to most examiners once they know it is there |
| 3 | Loud, no thrill | Obvious on routine auscultation |
| 4 | Loud, with a palpable thrill | A buzzing vibration can be felt with the palm |
| 5 | Heard with the stethoscope barely touching the chest | Very loud; thrill present |
| 6 | Heard with the stethoscope just off the chest | Loudest grade; thrill present |
The grade measures loudness, not how damaged the valve is. MSD Manuals notes regurgitant murmurs are louder with high-velocity flow and softer with high-volume flow, so a soft murmur can still come from a significant leak. Compare against the client's documented baseline rather than the number alone.
Systolic vs diastolic: the murmur types worth knowing
Timing is the first sort. Systolic murmurs happen between S1 and S2 while the ventricles empty. Diastolic murmurs happen between S2 and the next S1 while they fill. MSD Manuals is blunt that diastolic murmurs are always abnormal, while some systolic ejection murmurs are innocent.
| Lesion | Timing | Heard best | Clue |
|---|---|---|---|
| Aortic stenosis | Midsystolic, crescendo then decrescendo, harsh | Upper sternal borders, client leaning forward | Radiates to the carotids |
| Mitral regurgitation | Holosystolic, S1 to S2 | Apex, client on left side | Radiates to the left axilla |
| Mitral valve prolapse | Late systolic | Apex | Louder on standing or with Valsalva |
| Ventricular septal defect | Holosystolic | Lower left sternal border | Common congenital cause in children |
| Aortic regurgitation | Early diastolic | Base of the heart, client sitting up and leaning forward | Always pathologic |
| Mitral stenosis | Mid-diastolic, low-pitched | Apex with the bell | Always pathologic |
Positioning matters as much as location. Leaning forward brings aortic murmurs closer to the chest wall, and lying on the left side brings the apex closer for mitral sounds.
How to remember heart murmurs without memorizing a list
Start from what the valves should be doing. During systole the aortic valve is open and the mitral valve is shut. So an aortic valve that will not open fully (stenosis) or a mitral valve that will not seal (regurgitation) makes noise in systole. During diastole the roles swap: aortic regurgitation and mitral stenosis are diastolic.
Students often compress this into the mnemonic MR ASS and MS ARD. It works for the four classic left-sided lesions, but it is incomplete. It leaves out mitral valve prolapse, ventricular septal defect, right-sided valve lesions and innocent murmurs, and it says nothing about where each murmur is loudest or how it radiates. Use the valve logic to rebuild it under pressure.
Worked example: a new murmur in a hypothetical client
Hypothetical scenario, not a real exam item: a 71-year-old client reports nearly fainting while climbing stairs and chest tightness on exertion. The nurse hears a harsh grade 3 systolic murmur at the second right intercostal space that carries up into the neck.
Worked example
- Timing: between S1 and S2, so systolic.
- Location: second right intercostal space, the aortic area.
- Radiation: toward the carotids.
- Symptoms: exertional near-syncope and chest tightness, two of the syncope, angina and dyspnea triad for aortic stenosis.
- Grade: 3, loud without a thrill.
The wrong move is reassuring the client that murmurs are common in older adults. That is true for some innocent murmurs, but a harsh murmur with exertional symptoms needs reporting. Encouraging a brisk walk to test tolerance is also wrong, since exertion is what triggers the syncope.
Innocent murmurs and nursing interventions
MedlinePlus lists pregnancy, exercise, fever and anemia as settings where harmless murmurs appear, and many children have normal developmental murmurs. A murmur that comes with chest pain, fainting, shortness of breath or bluish skin is the one to escalate, and diastolic timing always moves it out of the innocent group.
Nursing interventions are assessment and communication. Describe grade, timing, location, radiation and the position used; compare with prior notes; check vital signs, lung sounds and edema for heart failure cues; and report any murmur that is new or louder. Teaching focuses on symptoms that should prompt a call.
Sources and further reading
MSD Manual Professional Version: Cardiac Auscultation. Grades 1 to 6 and diastolic 1 to 4, ejection vs holosystolic vs late systolic murmurs, diastolic murmurs always abnormal, flow velocity vs volume effect, maneuvers, positioning.
MSD Manual Professional Version: Aortic Stenosis. Harsh crescendo-decrescendo murmur at the upper sternal borders, leaning forward, radiation to the carotids, syncope, angina and dyspnea.
MSD Manual Professional Version: Mitral Regurgitation. Holosystolic murmur at the apex in left lateral position radiating to the left axilla.
MedlinePlus: Heart murmurs. Definition, innocent murmurs in pregnancy, exercise, fever and anemia, pediatric causes, thrill at grade 4, symptoms that need care.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our cardiovascular practice questions are the closest set to what this page covers.
Common questions
How do you remember heart murmurs?
Think about valve position. In systole the aortic valve is open and the mitral is closed, so aortic stenosis and mitral regurgitation are systolic. In diastole it reverses, so aortic regurgitation and mitral stenosis are diastolic. The MR ASS and MS ARD mnemonic encodes the same idea.
How are murmurs graded?
Systolic murmurs use a 1 to 6 loudness scale. Grade 1 is barely audible, grade 3 is loud without a thrill, grade 4 is loud with a palpable thrill, and grade 6 is heard with the stethoscope off the chest. Diastolic murmurs use a 1 to 4 scale.
What is the nursing intervention for a heart murmur?
Assess and document grade, timing, location and radiation, compare with the baseline, check for heart failure cues such as crackles and edema, and report any new or changed murmur. Teach the client to report chest pain, fainting or breathlessness.
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