Lecture Notes on Heart Sounds and Heart Murmurs

Introduction

• High-yield topic for medical exams (USMLE, COMLEX).
• Importance of understanding both visual and acoustic aspects of heart sounds.
• Video aims to equip with comprehensive knowledge on heart sounds.

Normal Heart Sounds

• S1 and S2 Sounds: "Lub-dub" sound pattern.
  • S1 (Lub): Closure of mitral and tricuspid valves, marking the beginning of systole.
  • S2 (Dub): Closure of aortic and pulmonary valves, marking the beginning of diastole.
• Cardiac Cycle Phases:
  • Systole: Between S1 and S2 (ventricular contraction).
  • Diastole: Between S2 and next S1 (ventricular relaxation).

Splitting of Heart Sounds

• Wide Splitting: Delayed right ventricle emptying (e.g., pulmonic stenosis, right bundle branch block).
  • Inspiration causes increased separation between A2 and P2.
• Fixed Splitting: No change in split during inspiration or expiration.
  • Associated with atrial septal defect (left to right shunt).
• Paradoxical Splitting: Delayed closure of the aortic valve (e.g., aortic stenosis, left bundle branch block).
  • Inspiration normalizes the split that is otherwise reversed.
• Mnemonics:
  • Wiper: Wide-Pulmonic-Right
  • First Aid: Fixed-Atrial
  • Pal: Paradoxical-Aortic-Left

High-Yield Pathological Murmurs

Aortic Stenosis

• Sound: Systolic crescendo-decrescendo ejection murmur.
• Associations:
  • Pulsus parvus et tardus: weak, delayed carotid upstroke.
  • SAD symptoms: Syncope, Angina, Dyspnea.
  • Causes: Age-related calcification (elderly), bicuspid aortic valve (young patients), Turner syndrome, rheumatic fever.

Mitral and Tricuspid Regurgitation

• Sound: Holosystolic, high-pitched, blowing murmur.
• Associations:
  • Mitral: Post-MI, left ventricular dilatation, infective endocarditis.
  • Tricuspid: Intravenous drug use, Marfan syndrome, pulmonary hypertension.

Mitral Valve Prolapse

• Sound: Late systolic crescendo with a mid-systolic click.
• Associations: Connective tissue disorders (e.g., Marfan syndrome, Ehlers-Danlos).
  • Progression to mitral regurgitation over time.

Ventricular Septal Defect (VSD)

• Sound: Holosystolic, harsh murmur (similar to mitral/tricuspid regurgitation but harsher).
• Associations: Genetic syndromes (Down syndrome, Edward syndrome, Patau syndrome).

Aortic Regurgitation

• Sound: Diastolic, decrescendo high-pitched blowing murmur.
• Associations:
  • Chronic: Bicuspid aortic valve, connective tissue disorders.
  • Acute: Infective endocarditis.
  • Water hammer pulse, De Musset's sign (head bobbing).

Mitral Stenosis

• Sound: Diastolic opening snap followed by delayed diastolic rumbling.
• Associations:
  • Rheumatic fever, lupus, rheumatoid arthritis.
  • Mimickers: Left atrial myxoma, bacterial endocarditis.
  • Mnemonic: MS OS (operating system = Microsoft).

Patent Ductus Arteriosus (PDA)

• Sound: Continuous machine-like murmur.
• Associations: Congenital rubella, premature infants (fetal alcohol syndrome).
• Treatment: Closure with indomethacin or kept open with prostaglandins.

Conclusion

• Heart sounds and murmurs are vital for diagnosing cardiac conditions in exams and clinical practice.
• Understanding the physiological and pathological processes enhances comprehension and retention.