If you are a smoker the bronchi will be seen prominent in X rays. YOUR AGE IS ALSO NEEDED .Just by one sentence Xray cannot be reported There can be a number of reasons why this may occur. However, the most common reason is taking a deep breath in when the x-ray is taken. A lot of time prominent bronchovascular markings are of no significance.
That being said, if the markings are prominent in someone with a weak heart, it could indicate fluid accumulation in the lung. This can occur because the weak heart fails to pump blood effectively throughout the body.