widening of pulse pressure

[trgf]

Which would be the most likely cause of a repetitive, widened pulse pressure together w/ unusually large lv stroke volumes and a heart murmur? I couldn't understand the explanation given by Uworld at all.. it talks about
Ao regurg. restriction of left ventricular filing resulting in a reduced lv end diastolic volume, and that at a given level of contractility this would cause rduction in sv.; lower stroke volume result in lower pulse pressures.
My question is: why shouldn't the edv be increased as a result of the regurgitation? I thought that the increase in edv leads to progressively less efficient contraction and hence lower pulse?
Or is Uworld talking about an event that happens very early on?

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[greatnt249]

Which would be the most likely cause of a repetitive, widened pulse pressure together w/ unusually large lv stroke volumes and a heart murmur? I couldn't understand the explanation given by Uworld at all.. it talks about
Ao regurg. restriction of left ventricular filing resulting in a reduced lv end diastolic volume, and that at a given level of contractility this would cause rduction in sv.; lower stroke volume result in lower pulse pressures.
My question is: why shouldn't the edv be increased as a result of the regurgitation? I thought that the increase in edv leads to progressively less efficient contraction and hence lower pulse?
Or is Uworld talking about an event that happens very early on?

Aortic regurgitation is usually caused by blood leaking back through a defective aortic valve. This leak occurs during diastole, and since this leak results in a lower volume of blood being in the aorta (as compared to the volume that would be there with no leak), the pressure in the aorta is lower as well. Systolic pressure does not usually change because the body can compensate for the regurgitation with a sympathetic response. Since the diastolic pressure drops and the systolic pressure doesn't (or at least not as much as the diastolic pressure), the pulse pressure (SP-DP) widens.

Since the blood flows back through the damaged valve during diastole, the body is effectively sensing a reduced cardiac output compared to that of a normal functioning cardiovascular system. The sympathetic compensation attempts to correct for this by increasing the heart rate/contractility and peripheral resistance, since the heart must pump out more blood per ventricular contraction to get the same amount of blood out to the periphery as in a normal state (since a percentage of blood is "lost" per contraction to regurgitation). This is where your "unusually large stroke volume" comes from.

As for the heart murmur, well, that's just the sound of blood flowing turbulently through the damaged valve. Since the regurgitation occurs early in diastole, that's when the murmur should be heard.

Feel free to point out any mistakes in my reasoning; I'm here to learn as well.