Hi guys,
I've put a lot of thought in finding out how the physics of shunts in the human body (esp. the heart) works, but I just can't figure it out. I thought maybe one of you guys could help me out? Because I really want to understand this.
Example 1- PDA: The pulmonary arteries usually receive blood only from the right ventricle (~ 25 mmHg). Now with the shunt open, they also receive blood from the aorta (~120 mmHg in systole). And since the left ventricle has to increase the output volume, there is hypertrophy of the left ventricle. BUT:
1. What about the right ventricle? I mean the pressure of the aorta is so much higher, shouldn't the blood coming from the aorta just be pushing back the blood from the right ventricle ? I know this doesn't happen, but why? Why isn't there an acute dilation of the right ventricle?
2. Because of the PDA, the pulmonary arteries receive the blood from 2 sources (aorta + RV). Now how much blood from each source is exactly getting inside the pulmonary arteries? Assuming (!) the cross sections of the pulmonary trunk and the Ductus arteriosus are the same: Would the blood flow from the DA to the pulmonary arteries be 5 times more than from the right ventricle? (120mmHg / 25 mmHg ~ 5) If this was the case, then there should be a backlog in the right ventricle which should lead to hypertrophy?
So what I'm basically asking is: What are the physical rules when there is a shunt between 2 blood vessels?
Example 2 - VSD: When there is a connection between the RV and the LV, how can the LV build up pressure? After 25mmHg, the pulmonary valves open and blood can rush to the lungs. How come the there isn't even a drop in systemic pressure ??
Thanks for helping me out guys, appreciate it!
I've put a lot of thought in finding out how the physics of shunts in the human body (esp. the heart) works, but I just can't figure it out. I thought maybe one of you guys could help me out? Because I really want to understand this.
Example 1- PDA: The pulmonary arteries usually receive blood only from the right ventricle (~ 25 mmHg). Now with the shunt open, they also receive blood from the aorta (~120 mmHg in systole). And since the left ventricle has to increase the output volume, there is hypertrophy of the left ventricle. BUT:
1. What about the right ventricle? I mean the pressure of the aorta is so much higher, shouldn't the blood coming from the aorta just be pushing back the blood from the right ventricle ? I know this doesn't happen, but why? Why isn't there an acute dilation of the right ventricle?
2. Because of the PDA, the pulmonary arteries receive the blood from 2 sources (aorta + RV). Now how much blood from each source is exactly getting inside the pulmonary arteries? Assuming (!) the cross sections of the pulmonary trunk and the Ductus arteriosus are the same: Would the blood flow from the DA to the pulmonary arteries be 5 times more than from the right ventricle? (120mmHg / 25 mmHg ~ 5) If this was the case, then there should be a backlog in the right ventricle which should lead to hypertrophy?
So what I'm basically asking is: What are the physical rules when there is a shunt between 2 blood vessels?
Example 2 - VSD: When there is a connection between the RV and the LV, how can the LV build up pressure? After 25mmHg, the pulmonary valves open and blood can rush to the lungs. How come the there isn't even a drop in systemic pressure ??
Thanks for helping me out guys, appreciate it!
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