Physiological Adaptation Q 122

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Which of the following complications is indicated by a third heart sound (S3)?

  

     A. Ventricular dilation

     B. Systemic hypertension

     C. Aortic valve malfunction

     D. Increased atrial contractions

    

    

Correct Answer: A. Ventricular dilation

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Rapid filling of the ventricles causes vasodilation that is auscultated as S3. The third heart sound (S3) is a low-frequency, brief vibration occurring in early diastole at the end of the rapid diastolic filling period of the right or left ventricle

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Option B: Systemic hypertension can result in a fourth heart sound. The fourth heart sound is a low-pitched sound coincident with late diastolic filling of the ventricle due to atrial contraction. It thus occurs shortly before the first heart sound. Although it is also called the atrial sound, and its production requires an effective atrial contraction, the fourth heart sound is the result of vibrations generated within the ventricle.

Option C: Aortic valve malfunction is heard as a murmur. One in three elderly people have a heart murmur because of the scarring, thickening, or stiffening of their aortic valve. That’s aortic sclerosis. It’s usually not dangerous, since the valve can work for years after the murmur starts.

Option D: Increased atrial contractions can cause a fourth heart sound. Common theoretic mechanisms for this condition are based around abnormal automaticity of the cardiac myocytes, increased eliciting events from chemical or physical instigators, and reentry of a retrograde impulse. For these causes, structural heart damage or chemical use may be found during the history and physical examination.

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