Cardiac Murmurs: Characteristics, Classification

Cardiac murmurs are prolonged series of audible vibrations of varying intensity (loudness), frequency (pitch), configuration, and duration. Heart murmurs can be preliminarily identified by a stethoscope.

Characteristics of Cardiac Murmur

1. Timing.
2. Dynamic auscultation.
3. Location.
4. Duration.
5. Configuration.
6. Intensity.
7. transmission
8. Frequency.

Classification of murmur Based on the Timing

Systolic Murmur

Systolic murmurs are heard between S1 and S2

Diastolic Murmurs

Diastolic murmurs are heard between S2 and S1. In the early part, an Early diastolic Murmur is heard. In the middle part, a mid-diastolic Murmur is heard, and in the later part, it is unusual to hear a murmur.

Continuous Murmurs

A continuous murmur is heard between S1 and S2, S2 and S1. It is seen in conditions that have Increased blood flow. They are

• Venous hum
• Mammary Souffle
• Hemangioma
• Acute alcoholic hepatitis: increased flow across the liver
• Hepatoma and Renal cell Carcinoma 

The continuous flow of blood from a high-pressure area to a low-pressure area is a reason for the development of continuous murmurs. From the Aorta, blood enters either the Right atrium or the right ventricle. 

If the Blood enters through the ruptured sinus. It is called the Ruptured sinus of Valsalva. It is present during both the systole and diastole. This is known as continuous murmurs. This is Seen in

• Coarctation of Aorta
• Branched pulmonary stenosis.
• Carotid occlusion
• Renal artery occlusion
• Femoral artery occlusion
• Mesenteric artery occlusion

Also Read: QRS Interval Abnormalities

Grading of Murmurs

Systolic murmurs are graded with the help of Levine Grading. As the name suggests this grsdig system was Classified by Levine. Levine Grading has 6 grades: grade 1/6, 2/6, 3/6, 4/6, 5/6, 6/6

• Grade ⅙: it is the lowest intensity, faintest murmur. It is heard only with close concentration in a quiet room. Both the Patient and clinician must be relaxed in order to listen this murmur.
• Grade 2/6: this murmur is soft, faint murmur. It can be detected easily.
• Grade 3/6: moderately loud murmur. There is No thrill in this murmur.(palpable murmur)
• Grade 4/6: very loud murmur and is associated with thrill.
• Grade ⅚: extremely loud murmur. Heard even with  the Edge of the stethoscope placed over the chest wall. It is also accompanied by thrill.
• Grade 6/6: exceptionally loud and is Heard even the stethoscope is placed near the chest wall.

Configuration/ Shape of the murmur 

• Decrescendo murmur: intensity is high in the beginning, and then intensity decreases
  • Seen in AR- early Diastolic Murmur
  • Regurgitation is maximum in the early part of diastole
• Crescendo- Decrescendo murmur:(diamond shaped)
  • Increases intensity, reaches the peak, and then the intensity decreases
  • Seen in Aortic stenosis
• Plateau Shaped Murmur:
  • The same intensity is maintained
  • E.g.: Pansystolic Murmur- Mitral regurgitation 

Named Murmurs

Following are some named cardiac and non cardiac murmurs. These are explained in great detail on the prepladder application under the SS Medicine section. These give a clear diffrential diagnosis of the disease. The topic of dynamic auscultation also is explained in detail on the app.

Cardiac murmurs

1. Carey Coombs Murmur
2. Austin Flint murmur: 
3. Graham steell murmur
4. Rytand's murmur: 
5. Mill wheel murmur
6. Dock's murmur
7. Gallaverdin phenomenon
8. Cole Cecil murmur
9. Gibsons murmur
10. Still's murmur

Non-Cardiac:

1. Men's Lerman scratch: Thyrotoxicosis 
2. Cruveilhier baumgarten murmur: portal HTN.

Frequently Asked Questions:

Q: What is the term for a murmur with high intensity in the beginning and then a decrease in intensity, often seen in aortic regurgitation?

Answer: Decrescendo

Q: What causes an increase in the intensity of a diastolic murmur in pulmonary regurgitation (PR)?

Answer: Inspiration

Q: What is the grading scale used for systolic murmurs?

Answer: Levine

Q: Which maneuver decreases venous return and causes a decrease in the intensity of heart sounds and murmurs?

Answer: Valsalva

Also Read: High-Yield Image Based Question on ECG

Hope you found this blog helpful for your NEET SS Medicine Cardiovascular Preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.