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Old 07-19-2011
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Stethoscope The mechanism of splitted second heart sound during inspiration!

A 24-year-old woman undergoes an annual physical examination for participation on the varsity track team at her college. While auscultating her heart sounds, the sports medicine physician instructs the woman to take in a deep inspiration. During this maneuver, he detects splitting of the second heart sound. Which of the following is the mechanism underlying this finding?
A. A decrease in heart rate
B. An increased left ventricular stroke volume
C. Delayed closing of the aortic valve
D. Delayed opening of the mitral valve
E. Delayed closing of the pulmonic valve
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E. Delayed closing of the pulmonic valve
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Originally Posted by bebix View Post
E. Delayed closing of the pulmonic valve
Hey bebix can you explain your answer? I thought it was delayed closure of aortic valve? Doesn't the sound of aortic valve closure overcome the sound of pulmonic valve closure ?
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Old 07-19-2011
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Default Ans.

E.Delayed closing of the pulmonic valve.
During inspiration the intra thoracic pressure drops, allowing more blood pumped into the right auricle, right ventricle volume stroke increases, simultaneously increasing pulmonary vessel capacity, therefore, more blood goes through the pulmonic valve into the pulmonic circulation, so there is a delay in the pulmonic valve closing to allow this extra blood flow to occur.

Last edited by NGaleas; 07-20-2011 at 02:01 PM.
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Tx. @NGaleas!

The mechanism of splitted second heart sound during inspiration!-sounds.jpeg
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Old 07-20-2011
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ok so i think that closure of aortic valve is before pulmonic valve... so is this 2nd heart sound splitting normal during inspiration.. I don't think so???
I think my ans was delayed closure of aortic valve but bebix has proved it that its cuz of delayed pulmonic valve closure!
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Old 07-20-2011
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E. Delayed closing of the pulmonic valve
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Correct Answer answer

The correct answer E
The second heart sound (S2) is associated with the closing of the aortic and pulmonic valves. The aortic valve normally closes slightly before the pulmonic valve, resulting in a splitting of the second heart sound into two components. During inspiration, the closing of the pulmonic valve is delayed, resulting in a prolongation of the interval between the two components of the second heart sound. During inspiration, the preload on the right heart is increased, resulting in a larger stroke volume, which causes the delay in the closing of the pulmonic valve. Closure of the mitral valve and tricuspid valves are associated with the first heart sound (S1). Heart rate is higher during inspiration than during expiration.
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Old 07-21-2011
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Default E E

the answer is E
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Old 07-30-2011
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Help Explanation please !!!

Dear all

1) I am having some troubles understanding the pathophysiology of pulsus paradoxus in asthma, sleep apnea, and constrictive pericarditis. How does the mechanism of pulsus paradoxus differ in each.
I know its mechanism in tamponade (IV bulging towards LV causing further LV compliance reduction of the already reduced during normal inspiration).

2) Kussmal's sign, what diseases it appears in and how does its mechanism differ in cardiac tamponade than pericarditis.

I would really appreciate your help, thanks.
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Cardiovascular-, Clinical-Signs, Figures-, Physiology-, Respiratory-, Step-1-Questions

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