Summary of "Heart Murmurs and Heart Sounds: Visual Explanation for Students"
Summary of "Heart Murmurs and Heart Sounds: Visual Explanation for Students"
This educational video by Tom from Zero to Finals provides a comprehensive overview of Heart Sounds and murmurs, aimed at medical students preparing for exams. It explains the physiology behind normal and abnormal Heart Sounds, describes common Heart Murmurs, and offers practical tips for auscultation and clinical assessment.
Main Ideas and Concepts
1. Normal Heart Sounds (S1 and S2)
- S1 ("lub"): Caused by closing of atrioventricular valves (mitral and tricuspid) at the start of ventricular systole to prevent backflow into atria.
- S2 ("dub"): Caused by closing of semilunar valves (aortic and pulmonary) at the end of systole to prevent backflow into ventricles.
- The typical heart sound heard during auscultation is the "lub-dub" of S1 followed by S2.
2. Additional Heart Sounds (S3 and S4)
- S3: Heard shortly after S2, associated with rapid ventricular filling causing tension on chordae tendineae ("twang" sound). Normal in young people, but in older adults may indicate heart failure due to stiff ventricles.
- S4: Heard just before S1, always abnormal, caused by atrial contraction against a stiff, non-compliant ventricle (e.g., hypertrophy). Sounds like "lub-lub-dub."
3. Auscultation Techniques
- Use bell of stethoscope for low-pitched sounds; diaphragm for high-pitched sounds.
- Listen over four valve areas:
- Pulmonary: 2nd intercostal space, left sternal border
- Aortic: 2nd intercostal space, right sternal border
- Tricuspid: 5th intercostal space, left sternal border
- Mitral (apex): 5th intercostal space, midclavicular line
- Herb’s point (3rd intercostal space, left sternal border) is optimal for Heart Sounds.
- Special maneuvers:
- Left lateral decubitus position to better hear Mitral Stenosis.
- Sitting up, leaning forward, and exhaling to better hear Aortic Regurgitation.
4. Mnemonic for Murmur Assessment: SCRIPT
- Site: Where is the murmur loudest?
- Character: Soft, blowing, crescendo (getting louder), decrescendo (getting quieter), or crescendo-decrescendo.
- Radiation: Does the murmur radiate (e.g., carotids in Aortic Stenosis, left axilla in Mitral Regurgitation)?
- Intensity: Graded 1 to 6 (subjective scale of loudness and palpability).
- Pitch: High or low (indicates velocity).
- Timing: Systolic or diastolic.
5. Grading Murmurs
- Grade 1: Barely audible.
- Grade 2: Quiet but audible.
- Grade 3: Easily heard.
- Grade 4: Easily heard with palpable thrill.
- Grade 5: Heard with stethoscope barely touching chest.
- Grade 6: Heard with stethoscope off the chest.
6. Heart Muscle Changes: Hypertrophy vs. Dilatation
- Hypertrophy: Thickening of heart muscle due to increased workload (e.g., stenotic valve).
- Dilatation: Stretching and thinning of heart muscle due to volume overload (e.g., regurgitant valve).
- Examples:
- Mitral Stenosis → left atrial hypertrophy.
- Aortic Stenosis → left ventricular hypertrophy.
- Mitral Regurgitation → left atrial dilatation.
- Aortic Regurgitation → left ventricular dilatation.
Detailed Descriptions of Common Murmurs
1. Mitral Stenosis
- Narrowing of mitral valve, often due to rheumatic heart disease or infective endocarditis.
- Mid-diastolic low-pitched rumbling murmur due to slow blood flow.
- Loud S1 due to thickened valve snapping shut.
- Associated signs: tapping apex beat, malar flush (red cheeks), atrial fibrillation.
- Sound: "lub-dub-rumble."
2. Mitral Regurgitation
- Incompetent mitral valve allows backflow during systole.
- Pansystolic (holosystolic) high-pitched blowing murmur ("burrr burrr").
- Radiates to left axilla.
- Associated with congestive heart failure and sometimes an S3.
Category
Educational
