Heart enzymes are proteins found within the heart muscle cells, according to Everyday Health. The major heart enzymes are troponin and creatine phosphokinase. While the former controls the contraction of the heart muscles, the latter controls the energy management of the heart.
Although heart enzymes are meant to work within the heart, they are also found in the blood, as stated by Everyday Health. However, the level of heart enzymes in the bloodstream rises when the cardiac muscles are damaged as a result of conditions such as heart surgery and heart attack.
Doctors can determine how recently heart damage has occurred by measuring the amount of heart enzymes in the blood, says About.com. For instance, in myocardial infarction damage, the heart releases creatine phosphokinase into the bloodstream four to six hours after the damage has occurred, and its blood level peaks after 24 hours. On the other hand, the heart releases troponin into the bloodstream two to six hours following a heart attack, and its level peaks after 12 to 26 hours.
Other organs and tissues such as the brain and skeletal muscles also contain heart enzymes, claims Everyday Health. Damage to these tissues may also lead to the rise in the level of heart enzymes in the bloodstream.