Lecture Notes on Heart Murmurs

Introduction

• Presenter: Tom from Zero to Finals
• Topic: Heart Murmurs
• Additional Resources: Available at Zero to Finals website and the cardiology section of the Zero to Finals Medicine book

Normal Heart Sounds

• S1 (First Heart Sound):
  • Caused by closing of atrioventricular valves (tricuspid and mitral)
  • Occurs at the start of systolic contraction
  • Prevents backflow into atria
• S2 (Second Heart Sound):
  • Caused by closing of semilunar valves (pulmonary and aortic)
  • Occurs at the end of systolic contraction
  • Prevents backflow into ventricles
• Auscultation: Heard as a "lub-dub" sound

Abnormal Heart Sounds

Third Heart Sound (S3)

• Timing: 0.1 seconds after S2
• Cause: Rapid ventricular filling causing chordae tendineae to "twang"
• Normal in Young Patients: Indicating good ventricular filling
• Abnormal in Older Patients: May indicate heart failure
• Sound: "Lub-dub-dub"

Fourth Heart Sound (S4)

• Timing: Just before S1
• Cause: Atria contracting against a stiff ventricle
• Always Abnormal: Indicates hypertrophic or stiff ventricle
• Sound: "Le-lub-dub"

Heart Murmurs

• Technique: Use the bell for low-pitched, 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
• Special Maneuvers:
  • Roll patient on left side (mitral stenosis)
  • Sit up, lean forward, breath out (aortic regurgitation)

Features of Murmurs (SCRIPT Mnemonic)

• S: Site (where murmur is loudest)
• C: Character (soft, blowing, crescendo, etc.)
• R: Radiation (carotids or axilla)
• I: Intensity (grade)
• P: Pitch (high 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 palpable thrill
• Grade 5: Heard with stethoscope barely touching chest
• Grade 6: Heard with stethoscope off chest

Heart Conditions

Hypertrophy and Dilatation

• Hypertrophy: Thickening of heart muscle due to stenotic valve (e.g., mitral stenosis)
• Dilatation: Thinning and expansion due to regurgitant valve (e.g., mitral regurgitation)

Common Heart Murmurs

Mitral Stenosis

• Causes: Rheumatic heart disease, infective endocarditis
• Sound: Mid-diastolic, low-pitched rumbling
• Auscultation: Loud S1, "lub-dub-dur"
• Clinical Features: Tapping apex, malar flush, atrial fibrillation

Mitral Regurgitation

• Cause: Incompetent mitral valve
• Sound: Pan-systolic, high-pitched
• Radiation: To left axilla
• Associations: Congestive heart failure, third heart sound
• Causes: Age-related, ischemic heart disease, connective tissue disorders

Aortic Stenosis

• Prevalence: Most common
• Sound: Ejection systolic, crescendo-decrescendo
• Radiation: To carotids
• Clinical Signs: Slow rising pulse, narrow pulse pressure
• Symptoms: Exertional syncope
• Causes: Age-related calcification, rheumatic disease

Aortic Regurgitation

• Cause: Incompetent aortic valve
• Sound: Early diastolic, soft
• Clinical Features: Corrigan’s pulse, heart failure
• Associations: Austin Flint murmur
• Causes: Age-related, connective tissue disorders

Conclusion

• Resources: More notes and illustrations on Zero to Finals website
• Exam Preparation: Test section with practice questions
• Career Advice: Blog on medical career tips
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