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Guys I am a little confused on this topic. I understand squatting increases systemic vascular resistance and hence its helpful in R->L shunts.
But I've read conflicting things on what it does to venous return...does it decrease because of increased TPR or does it increase because its squeezing blood back up to the RA?
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if i am not wrong its becoz of compression of inf vena cava ??
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Squating-- inc.systemic vascular resistance ,so dec. right to left shunt and --->inc. pulmonary
blood flow and---> improves arterial oxygenation...
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yes sodium thank you, but I understand up to that point...I don't understand what it does to venous return?
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1. Squatting position
increases peripheral vascular resistance -> increases afterload
application : tetralogy of fallot is a cyanotic congenital heart disease because of the right to left shunt. So if the patient squats then the increased peripheral vascular resistance impedes emptying of the left ventricle. This increased afterload limits or slows down the right to left shunting.
2. Valsalva:
Results in positive intrathoracic pressure which leads to decreased venous return to heart/decreased preload
3. Standing
Increases peripheral vascular resistance -> deceases venous return
4. Supine
Decreased peripheral vascular resistance. Increased venous return to heart
application: in hypertrophic cardiomyopathy, the murmur intensity is determined by the proximity of the anterior leaflet of the mitral valve with the asymmetrically hypertrophied septum as the blood exits the left ventricle during systole.
Normally when the septum is not hypertrophied, there is no problem with the anterior leaflet causing obstruction. However, when the septum is hypertrophied, then the anterior leaflet is in closer proximity to the septum and thus the chances of causing obstruction increases.
In hypertrophic cardiomyopathy, to reduce the amount of obstruction and thus increase the distance between the anterior leaflet and septum, we need to increase the amount of blood. Thus, if we increase the preload, the presence of more blood will separate the anterior leaflet from the septum, resulting in less obstruction and decreasing the intensity of the murmur.
In contrast, standing up results in decreased venous return and thus decreased preload. With less preload there is less blood to separate the anterior leaflet from the hypertrophied septum, resulting in more obstruction and hence increased intensity of the murmur
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@simran: squatting increases both afterload (increased TPR) and preload (increased venous return)
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when u suddenly squat u are SQUEEZING THE VEINS OF THE LEGS...which r rather large.this essentially squeezes blood up into the heart like SQUUEZING ON A TUBE OF TOOTHPASTE(colgate of course)...drains da bllood from lowerextremities to chest..so inc in venous return..
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when we were in school we used to stand for about an hour in assembly.
as we stood for longer hours we would have venous pooling in the legs.
thus decreased preload leading to decreased supply to brain consequently followed by loss of consciousness.
so we were advised bunny our teachers to flex our legs so that our calf muscles would be contracts leading to rise in venous return and thus normal or increased heart work.
so i think squatting also should increase venous return
sorry if i am wrong
