Mitral regurge

[chillaxbro]

Uworld 943 talks about mitral regurgitation that is "volume dependent" vs "left ventricular size dependent".

Can someone explain the difference in pathophysiology and the relationship to how increasing/decreasing preload will affect the ratio of backward/forward flow?

---

Members don't see this ad.

 

[worldbeater]

Can someone explain the difference in pathophysiology and the relationship to how increasing/decreasing preload will affect the ratio of backward/forward flow

I don't know if this is exact right physiology, but the logic makes sense in my head and I am able to get a point on this question.

To understand preload, lets talk about the afterload first, which this question is hitting at. Afterload is the amount of blood present in the ventricle after ejection. In a case of mitral regurgitation (the differential you come to with the description in the stem), your having a problem during systole (during ejection), where blood is squirting back from left ventricle to the left atrium. The normal physiology in systole is the mitral valve is closed and the aortic valve is open to squeeze blood into the aorta and deliver it to the arterial system. But that's not the case here, it's going in the wrong direction. So to minimize the amount of blood that squirts backwards, we would want to decrease the afterload.

When they are asking the question, "which of the following would increase the ratio of forward flow volume to regurgitation flow volume in this patient?", they are asking what would make this value higher, which is increasing the numerator (forward flow) or decreasing the dominator (regurgitant flow). So, we could either decrease the regurgitant flow (afterload) -or- we could increase the numerator, which is forward flow. Forward flow is just your preload, or amount of blood present in the ventricle before ejection.

 

[chillaxbro]

I don't know if this is exact right physiology, but the logic makes sense in my head and I am able to get a point on this question.

To understand preload, lets talk about the afterload first, which this question is hitting at. Afterload is the amount of blood present in the ventricle after ejection. In a case of mitral regurgitation (the differential you come to with the description in the stem), your having a problem during systole (during ejection), where blood is squirting back from left ventricle to the left atrium. The normal physiology in systole is the mitral valve is closed and the aortic valve is open to squeeze blood into the aorta and deliver it to the arterial system. But that's not the case here, it's going in the wrong direction. So to minimize the amount of blood that squirts backwards, we would want to decrease the afterload.

When they are asking the question, "which of the following would increase the ratio of forward flow volume to regurgitation flow volume in this patient?", they are asking what would make this value higher, which is just increasing the numerator (forward flow) or decreasing the dominator (regurgitant flow). So, we could either decrease the regurgitant flow (afterload) -or- we could increase the numerator, which is forward flow. Forward flow is just your preload, or amount of blood present in the ventricle before ejection.

Yeah I got the answer right and I understand decreasing afterload will make MR better.

But reading the explanation talks about "volume dependent MR" vs "ventricular size dependent MR" and my question really is what those are

 

[worldbeater]

Yeah I got the answer right and I understand decreasing afterload will make MR better.

Nice.

But reading the explanation talks about "volume dependent MR" vs "ventricular size dependent MR" and my question really is what those are

Hmmm..not sure exactly. I would think both are the same thing, volume dependent meaning amount of blood regurgitation backwards and ventricular size determining the amount of blood that can move backwards. But if they are comparing them against each other, I guess not. Anybody else know?

 

[jqueb29]

Yeah I got the answer right and I understand decreasing afterload will make MR better.

But reading the explanation talks about "volume dependent MR" vs "ventricular size dependent MR" and my question really is what those are

Yeah this is kind of confusing. My best guess is that, when they say "ventricular size dependent MR", they're talking specifically about MR secondary to left heart failure. As the chamber dilates, this essentially stretches out the valve and displaces the papillary muscles (basically the dilation of the ventricle also dilates the valve). Since this is all due to systolic failure, I would assume that you have less back flow with this variety of MR than you would with the "volume dependent MR".

Not sure if that's right at all but it at least made sense to me as I typed it.