Question

what will happen if pulmonary veins are tied with a thread

Answer 1

Hii..
If pulmonary veins are tied with a thread then heart will not receive oxygenated blood from the lungs and hence it will not be able to transport oxygenated blood to the body parts
so the oxygen levels in a person can decrease and this can also be fatal..

hope this helps!

Answer 2

The main function of pulmonary veins is to bring oxygenated blood from the lungs to the blood. This oxygenated blood is then carried away by the aorta to the various parts of the body for cellular respiration and various other functions. Coronary arteries also give oxygenated blood to the heart which helps in its beating.
So, if the pulmonary veins are tied, the heart will not receive oxygen nor will the whole body and finally it will lead to death.

Hope it helps!!!