IF the blood vessel will not work :
You can have this three serious health problems.

1. Chest pain (Angina). 
When you have this symptom, you feel pain in your chest, arms, shoulders, or back. 

2. Heart attack.
 A heart attack appears when the blood vessel blocked near in your heart, then causing damage to the heart muscle.

3. Stroke. A stroke happen when the blood supply to your brain is blocked, causing your brain damaged. 

Hope this answer will help you :)