Heart Murmurs Lecture Notes

Introduction

• Presented by Tom from Zero2Finals.com
• Additional resources available on website and in the Zero2Finals Medicine book.

Normal Heart Sounds

S1 and S2

• S1: Caused by the closing of atrioventricular valves (tricuspid and mitral) at the beginning of ventricular systole.
• S2: Caused by the closing of semilunar valves (pulmonary and aortic) at the end of ventricular systole.
• Heard as a "lub-dub" sound during auscultation.

Additional Heart Sounds

• S3:
  • Heard 0.1 seconds after S2.
  • Indicates rapid ventricular filling; can be normal in young patients (15-40 years) but abnormal in older patients (may indicate heart failure).
  • Sounds like "lub-du-dub".
• S4:
  • Heard before S1.
  • Indicates stiff ventricles; always abnormal.
  • Sounds like "lulubdub".

Heart Murmurs

Listening Techniques

• Use the bell for low-pitched sounds and the diaphragm for high-pitched sounds.

Valve Areas for Auscultation:

• Pulmonary Area: 2nd intercostal space, left sternal border.
• Aortic Area: 2nd intercostal space, right sternal border.
• Tricuspid Area: 5th intercostal space, left sternal border.
• Mitral Area: 5th intercostal space, midclavicular line (apex).
• Erb's Point: 3rd intercostal space, left sternal border (best for listening to heart sounds).

Special Maneuvers

• Patient on left side to listen for mitral stenosis.
• Patient sits up, leans forward, and exhales for aortic regurgitation.

Features of a Murmur (Mnemonic: SCRIPT)

• S: Sight - where is it loudest?
• C: Character - soft, blowing, crescendo, decrescendo, or crescendo-decrescendo?
• R: Radiation - where does it radiate (e.g., carotids or axilla)?
• I: Intensity - grading the murmur.
• P: Pitch - high-pitched or low?
• T: Timing - systolic or diastolic?

Grading of Murmurs

• Grade 1: Difficult to hear.
• Grade 2: Quiet.
• Grade 3: Easy to hear.
• Grade 4: Easy to hear with a palpable thrill.
• Grade 5: Heard with stethoscope barely touching.
• Grade 6: Heard with stethoscope off the chest.

Hypertrophy and Dilatation of the Heart

• Hypertrophy: Thickening of heart muscle.
• Dilatation: Thinning and expansion of heart muscle.
• Caused by increased workload due to stenosis or backflow of blood due to regurgitation.

Specific Murmurs

Mitral Stenosis

• Narrowed mitral valve; causes difficulty in blood flow from left atrium to ventricle.
• Caused by rheumatic heart disease or infective endocarditis.
• Sound: Mid-diastolic low-pitched rumbling murmur; loud S1.
• Associated with tapping apex beat, malar flush, and atrial fibrillation.

Mitral Regurgitation

• Incompetent mitral valve allows backflow during systole.
• Sound: Pan-systolic murmur (high-pitched whistling).
• Radiates to the left axilla; associated with congestive cardiac failure.
• Causes include idiopathic weakening, ischemic heart disease, and connective tissue disorders.

Aortic Stenosis

• Narrow aortic valve; common valve disease.
• Sound: Ejection systolic murmur (crescendo-decrescendo).
• Radiates to carotids; associated with slow rising pulse and exertional syncope.
• Most common cause: idiopathic age-related calcification.

Aortic Regurgitation

• Incompetent aortic valve allows backflow into the left ventricle during diastole.
• Sound: Early diastolic soft murmur.
• Associated with Corrigan's pulse and Austin-Flint murmur.
• Causes include idiopathic age-related weakness and connective tissue disorders.

Conclusion

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