Need help with cardiac!

[sunnybabe]

Hi, I am in Pediatrics class right now and I love learning about cardiac. In my notes and lecture recording, it says that increased pulmonary blood flow (which in children are usually caused by congenital defects like VSD or ASD) will cause impaired myocardial functioning. As a result of this impairment, the heart has to work harder and the patient will be tachycardic, weak, and tired.

My rationale for all of this is that since the blood keeps going to the lungs, the body is unable to get enough O2 into the lungs since the lungs are filled with blood/fluid. Is this correct?

Also I was thinking that the heart keeps doing the left to right shunting that it can't keep enough blood to send out to the organs so it keeps working hard to get and keep blood from the lungs to send elsewhere.

I was also thinking that the continuous left to right shunt increases pressure in the pulmonary artery and the heart is working hard to overcome this pressure and eventually begins to fail ( backup of blood occurs as a result of this as well--> heart failure).

I also have in my notes that left ventricular hypertrophy occurs as a result of increased pulmonary blood flow. Is it because of that large amount of blood going from the lungs into the left atria and then left ventricle?

I was wondering if anyone could let me know if I am on the right track. If you could put in terms that would apply to both children and adults, that would be helpful. I want to make sure I understand how blood filling up in the lungs makes the heart "work harder". I know it should be common sense but I want to understand the patho part of it.

Thanks!