Enzymes are special molecules made up of amino acids that help to moderate the body's chemical reactions and responses in regards to specific function and structure. Enzymes that are found in heart muscle are called cardiac enzymes. Cardiac enzymes are released when the heart muscle is damaged, such as during a heart attack (myocardial infarction)and results in an elevated enzyme leve.l Troponin and Creatine Phosphokinase (CPK) are the chief cardiac enzymes and are important for diagnosing and treating many types of cardiac disorders.
When oxygen rich blood flow to the heart is disturbed or decreased by any degree due to narrowing of the arteries that lead to the heart, damage to the actual heart muscle occurs and cardiac enzymes are released into the blood. Damage or death of heart muscle causes the cell membranes to disintegrate, leading to enzyme leakage into blood which results in elevation in the levels of cardiac enzymes.
Cardiac enzymes do not leak into the bloodstream on a rapid basis, and in many cases may not even be considered elevated until six hours after the damage or death of the heart muscle occurs. In the early stages of a heart attack, cardiac enzymes may not be elevated. Repeated enzyme testing is normally done to confirm any cardiac diagnosis, and this is usually done in three eight-hour intervals.
One of the most common and reliably tested cardiac specific enzyme is creatinine phosphokinase (CPK). CPK is found in all types of muscle tissue (cardiac, skeletal and smooth muscle). When the heart muscle is damaged, the CPK-MB fraction is found in the blood. Elevated troponin enzymes are also considered an accurate indication that a heart attack with muscle damage has occurred.
There are a number of other cardiac related causes for elevated cardiac enzymes such as cardiac contusion, pericarditis and cardiac surgery. In these conditions, cardiac muscle is injured by a variety of causes including trauma and surgery which then cause a release of enzymes.
There are other conditions that can also cause elevated cardiac enzymes including chronic renal disease, hypothyroidism, diabetes, and brain infarcton. These all involve different types of muscle injury and may result in an elevated amount of cardiac enzymes to appear in the blood.