Heart Sounds and Murmurs Overview

Apr 10, 2025

Lecture on Heart Sounds and Murmurs

Importance

  • High-yield topic, especially for USMLE and COMLEX exams.
  • Questions may include visual amplitude depictions or audio files of heart sounds.
  • Understanding both visually and acoustically is crucial.

Structure of the Lecture

  1. Normal Heart Sounds
  2. Splitting of Heart Sounds
  3. High-Yield Murmurs

Normal Heart Sounds

  • S1: "Lub" - Mitral and Tricuspid valves closing, marking the start of systole.
  • S2: "Dub" - Aortic and Pulmonary valves closing, marking the start of diastole.
  • Cardiac Cycle: S1 to S2 marks systole, S2 to S1 marks diastole.
  • Audio: Familiarize with normal heart sounds to identify abnormalities.

Splitting of Heart Sounds

Types of Splitting

  1. Wide Splitting

    • Occurs when right ventricle emptying is delayed (e.g., Pulmonic stenosis, Right Bundle Branch Block).
    • Normal inspiration widens the gap between A2 and P2.

  2. Fixed Splitting

    • A2 and P2 split remains constant during inhalation and exhalation.
    • Caused by left to right shunt (e.g., Atrial Septal Defect).

  3. Paradoxical Splitting

    • A2 is delayed; P2 occurs first during expiration.
    • Caused by delayed aortic valve closure (e.g., Aortic stenosis, Left Bundle Branch Block).
    • Inspiration renormalizes the reversed split.

High-Yield Murmurs

Aortic Stenosis

  • Description: Systolic crescendo-decrescendo ejection murmur.
  • Associations: Pulsus parvus et tardus, SAD symptoms (Syncope, Angina, Dyspnea).
  • Etiology: Age-related calcification or bicuspid aortic valve (Turner syndrome).
  • Audio: Harsh, loud at first, then softer.

Mitral and Tricuspid Regurgitation

  • Description: Holosystolic, high-pitched blowing murmur.
  • Associations
    • Mitral: Ischemic heart disease, infective endocarditis.
    • Tricuspid: Intravenous drug use, Marfan's, pulmonary hypertension.
  • Audio: Continuous between S1 and S2.

Mitral Valve Prolapse

  • Description: Late systolic crescendo with mid-systolic click.
  • Associations: Connective tissue disorders (e.g., Ehlers-Danlos, Marfan's).
  • Audio: Unique mid-systolic click.

Ventricular Septal Defect (VSD)

  • Description: Holosystolic harsh murmur.
  • Associations: Genetic syndromes (e.g., Down syndrome).
  • Audio: Harsh, throughout systole.

Aortic Regurgitation

  • Description: High-pitched blowing early diastolic decrescendo murmur.
  • Associations: Infective endocarditis (acute), bicuspid aortic valve (chronic).
  • Unique Sign: Water hammer pulse, De Musset's sign (head bobbing).
  • Audio: Louder after S2, then tapers.

Mitral Stenosis

  • Description: Diastolic opening snap followed by delayed diastolic rumbling.
  • Associations: Rheumatic fever, mimickers like left atrial myxoma.
  • Audio: Unique opening snap after S2.

Patent Ductus Arteriosus (PDA)

  • Description: Continuous machine-like murmur.
  • Associations: Congenital rubella, prematurity.
  • Treatment: Prostaglandins to keep open, Indomethacin to close.

Conclusion

  • Understanding of heart murmur physiology and audio characteristics is crucial.
  • Use mnemonics to aid memory (e.g., "Wiper First Aid PAL").
  • Mastery of heart sounds and murmurs is key for medical exams and clinical practice.

Full transcript