Cardiac enzymes are released from the heart into the blood when the heart muscle is damaged. This can occur due to various conditions, including: 

• Myocardial infarction (heart attack): When blood flow to the heart muscle is blocked.
• Myocarditis: Inflammation of the heart muscle.
• Cardiac stress: During strenuous exercise or other intense physical activity.
• Heart failure: When the heart cannot pump blood effectively.

The specific cardiac enzymes released include: Creatine kinase (CK), Troponin T and I, and Myoglobin. 

When these enzymes are detected in the blood, it indicates that the heart muscle is damaged. The levels of these enzymes can help healthcare professionals diagnose the severity of the damage and monitor the patient's progress.