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Forward to Regurgitant Flow Ratio

6487 Views 10 Replies 7 Participants Last post by  angermngment
this is one of the questions of uw...but i cudnt understand the plz guys help me wid dis one-:toosad:

A 46 yr old Caucasian female presents to ur office becoz of easy fatiguability n exertional dyspnea. Auscultation of heart reveals a diminished first heart sound and an apical holosystolic murmur radiating to d axilla. Lungs have bibasilar crackles. There is no elevation of JVP or peripheral edema. Which of d following wud most likely increase forward to regurgitant volume ratio in this patient?

A. Decreasing LV preload
B. Increasing LV contractility
C. Decreasing LV afterload
D. Decreasing heart rate
E. Increasing left ventricular volume
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I'm not that great with cardiology, but I'll try this out.

So you're told the patient has a holosystolic murmur loudest at the apex that radiates to the axilla = Mitral Regurgitation.
By the way the decreased S1 is because your mitral and tricuspid valves close to produce S1 and your mitral valve is not closing that well because of the regurgitation.
You're also told the patient doesn't have a raised JVP or peripheral edema = NOT in heart failure
What are you being asked? You want to increase forward to regurgitant volume = you want the blood to move forwards to the LV instead of backwards to the LA like it normally does in MR.

What happens in MR?
The mitral valve (between the LA and LV) doesn't close properly. If it doesn't close properly then blood is leaking back into the LA during ventricular diastole (relaxation/filling). This means your LVEDV (preload) is lower than normal because blood that would've gone to the LV is able to go back to the LA. This also means you can't generate as high of a pressure as you would want to in the LV during ventricular systole (contraction) because blood is continually leaking back. If your LV systolic pressure is lower than normal then you have to use more effort to get the blood from the LV to the aorta and you're not able to send as much blood to the aorta during ventricular systole. (This is because blood always moves from high pressure to low pressure in the heart so blood can only move from the LV to the aorta when the pressure in the LV is higher than the pressure in the aorta.)
You want to increase the forward movement of blood (LA -> LV -> aorta) right? So either you have to increase your preload (LVEDV) because it's lower than normal in this case or you have to decrease your afterload (Aortic Diastolic Pressure or TPR). You want to decrease your afterload so that the pressure difference between the LV and Aorta becomes higher which allows you to move more blood from the LV to the Aorta.

Someone please check and make sure what I said is correct. Hope this helps you. :)
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I would think that decreasing the afterload is better than increasing the preload because if you increase the preload for a long time you may end up with eccentric hypertrophy (dilatation and hypertrophy) and eventually systolic heart failure. I'm not sure how you would just increase the preload without affecting the afterload or any other parameters.
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