Heart Murmurs Lecture Notes

Introduction

• Presenter: Tom from Zero to Finals.
• Topic: Heart Murmurs.
• Additional resources available at Zero to Finals website and in the cardiology section of Zero to Finals Medicine book.

Normal Heart Sounds

• S1 and S2
  • S1: Closing of the atrioventricular valves (tricuspid and mitral valves) at the start of systolic contraction.
  • S2: Closing of the semilunar valves (pulmonary and aortic valves) post-systolic contraction.
  • Auscultation: Heard as "lub dub" sound.
  • S3: Occurs 0.1 seconds after S2, linked to rapid ventricular filling and the chordae tendineae twanging. Normal in ages 15-40, may indicate heart failure in older patients.
  • S4: Heard before S1, always abnormal, indicates stiff or hypertrophic ventricle due to turbulent atrial flow.

Heart Murmurs

• Auscultation Techniques

  • Use bell for low-pitched, diaphragm for high-pitched sounds.
  • Valve auscultation points:
    • Pulmonary: 2nd intercostal space, left sternal border.
    • Aortic: 2nd intercostal space, right sternal border.
    • Tricuspid: 5th intercostal space, left sternal border.
    • Mitral: 5th intercostal space, midclavicular line.
    • Erb's Point: 3rd intercostal space, left sternal border.

• Special Maneuvers

  • Left lateral position for mitral stenosis.
  • Sit up, lean forward, breath out for aortic regurgitation.

Characteristics of Murmurs (SCRIPT Mnemonic)

• S: Site - where is murmur loudest?
• C: Character - soft, blowing, crescendo, decrescendo, crescendo-decrescendo.
• R: Radiation - carotids (aortic stenosis) or left axilla (mitral regurgitation).
• I: Intensity - grade of murmur.
• P: Pitch - high or low.
• T: Timing - systolic or diastolic.

Grades 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: Audible with stethoscope barely touching.
• Grade 6: Audible with stethoscope off the chest.

Hypertrophy and Dilatation

• Hypertrophy: Thickening of heart muscle due to pushing against stenotic valves.
  • Example: Left ventricular hypertrophy with aortic stenosis.
• Dilatation: Thinning and expansion due to leaky valves.
  • Example: Left atrial dilatation with mitral regurgitation.

Specific Murmurs

Mitral Stenosis

• Cause: Rheumatic heart disease, infective endocarditis.
• Sound: Mid-diastolic low-pitched rumbling, loud S1.
• Symptoms: Tapping apex beat, malar flush, atrial fibrillation.

Mitral Regurgitation

• Cause: Idiopathic age-related weakening, ischemic heart disease, infective endocarditis.
• Sound: Pansystolic, high-pitched whistling.
• Symptoms: Radiates to left axilla, congestive heart failure.

Aortic Stenosis

• Cause: Age-related calcification, rheumatic heart disease.
• Sound: Ejection systolic murmur, crescendo-decrescendo.
• Symptoms: Radiates to carotids, slow-rising pulse, exertional syncope.

Aortic Regurgitation

• Cause: Idiopathic weakening, connective tissue disorders.
• Sound: Early diastolic, soft.
• Symptoms: Corrigan's pulse, Austin Flint murmur, potential heart failure.

Conclusion

• Resources available on the Zero to Finals website including notes, illustrations, and exam questions.
• Encouragement to engage with content through likes, comments, and subscriptions.