pericardial friction rub

[Oh_Gee]

1. what is the cause of these sounds? is it just b/c the fluid rubs against the visceral and parietal pericardium whenever the heart does any movement at all?

2. why is pain worse during inspiration? is it b/c during inspiration, the thoracic cavity pressure decreases and volume increases. lower pressure=less pain?

3. why is pain less when sitting up and why is pain worse when laying down? i have no idea

4. why ST-elevation in all leads except aVR and V1? is it the same concept of what causes ST-depression in subendocardial infarction? except it's depression in pericarditis b/c it's the opposite layer
(CV Physiology | Electrophysiological Changes During Cardiac Ischemia)

5. why PR depression?

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[donovank730]

If you think of the parietal pericardium as being a thick and unstretchable membrane, when you inspire it increase blood flow into the right heart and than it fills the heart to the point where it is touching against the parietal pericardium.

It's the extra volume in the heart during inspiration that stretches it against the fixed pericardium and makes the friction rub worse

 

[Oh_Gee]

If you think of the parietal pericardium as being a thick and unstretchable membrane, when you inspire it increase blood flow into the right heart and than it fills the heart to the point where it is touching against the parietal pericardium.

It's the extra volume in the heart during inspiration that stretches it against the fixed pericardium and makes the friction rub worse

sitting up> decrease preload> decrease volume to heart> decrease pain

laying down> increase preload> increase volume to heart> increase pain.

is that right? not sure if laying down will cause increase in preload