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Old 07-06-2013
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Stethoscope Increase preload decrease murmur

How increase preload (reclining, beta blocker, squatting) decrease murmur intensity??
Source; goljan 3rd ed. pg 188 (C/F of HCM)
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Old 07-06-2013
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The intensity of certain murmurs decreases with an increase with preload. E.g murmurs of HOCM and mitral valve prolapse.
In HOCM, increasing the preload increases the ventricular volume. This reduces the obstruction that was causing the murmur, hence resulting in a decrease in intensity. Dehydration, and decreasing preload leads to a reduction in ventricular volume. This results in a smaller ventricular size and a worsening of obstruction, hence a worsening of murmur.

This is why b-blockers are used for patients with this disorder. B-blockers prolong diastole, thereby allowing for the filling of the ventricle and blah blah blah.
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medicalbiology (07-07-2013), Thrax_usmle (07-16-2013)


Audio-, Cardiovascular-, Clinical-Signs, Pathology-

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