I think Eisenmenger (shunt reversal) is actually R to L shunt.
It is observed in case of L to R shunt, with time right ventricle get hypertrophied and can overcome left ventricle.
It's due to pulmonary hypertension. Reversal shunt that is. Right ventricular hypertrophy is just a consequence of PH.
And why does Pulmonary hypertension arise in that case?
Too much blood going to the lungs causes edema and hypertrophy of the pulmonary vasculature.
Increased flow of blood through pulmonary vasculature in cases of left to right shunt.
Normally, the pulmonary system is a low pressure system 25 / 8 mm of hg in compared to the normal 120/80 mm hg of systemic vessels
The pressure increases in hope to reduce blood flow through the lungs..through the shunt.
But instead of being a protective response.. It ends up making the whole situation much more severe.
Plethoric lungs, basically.
Or it Is it due to hypoxia which causes pulmonary vasocontriction which leads to pulmonary hypertension?
Yes, that's a contributory factor too
Why too much blood going to lungs.. Is it due to compensatory effort by Increasing HR?
The left ventricle is stronger than the right. So more blood goes to the right ventricle. Hence, more blood to the lungs.
It's the shunt..Left side of heart has a higher pressure compared to the right side of heart..Hence in cases of ASD and VSD.
Due to free communication.. Blood flows from high pressure to low pressure system.
In case of right to left shunts..There is obstruction which doesnt let blood enter the lungs (eg tetralogy of fellot where there is pulmonary trunk stenosis)
So a right to left shunt.
Thanks for explaining it to me, you guys!