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[Skill Modules
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Heart Sounds & Murmurs
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Pathophysiology
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Pathophysiology: Heart Sounds & Murmurs
Splitting of the Second Heart Sound
Normal
- During expiration, A2 and P2 are separated by less than 30 msec and are
heard as a single sound
- During inspiration, P2 is delayed and A2 is slightly earlier due to changes
in systemic and pulmonary venous return causing prolonged right and shortened
left ventricular ejection
- In younger people, maximal splitting during inspiration is 40 to 50 msec
and decreases with age. In people 40 years and older, a single S2 during inspiration
and expiration may be normal.
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Causes of audible expiratory splitting
- Wide physiological splitting primarily due to delayed P2
- Reverse splitting primarily due to delayed A2
- Narrow physiological splitting
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Wide physiological splitting of the 2nd Heart Sound
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Delayed pulmonic closure
- RBBB (right bundle Branch block (delayed electrical activation of right
ventricle)
- Pulmonary stenosis (prolonged right ventricular mechanical systole)
- Atrial septal defect (decreased impedance in pulmonary vascular bed)
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Early aortic closure
- Ventricular septal defect (shortened left ventricular mechanical systole)
- Mitral insufficiency (shortened left ventricular mechanical systole)
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Reverse splitting of the Second Heart Sound
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Delayed aortic closure
- LBBB (left bundle Branch block (delayed electrical activation of left
ventricle or prolonged left ventricular mechanical systole)
- Hypertensive cardiovascular disease (prolonged left ventricular mechanical
systole)
- Atherosclerotic heart disease (prolonged left ventricular mechanical
systole)
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Early pulmonic closure
- Wolff-Parkinson White (early activation of right ventricle)
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Narrow physiological splitting
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Increased intensity and high frequency of P2
- Severe pulmonary hypertension {can have normal interval (<30 msec)
but both components are audible throughout respiratory cycle.
Murmurs: pathophysiology is discussed with the heart cycle description in each individual murmur category. |
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