What Are Cardiac Enzymes And What Do They Do In The Body?

Understand cardiac enzymes, the role they play in proper functioning of the heart, and their usefulness.

What are cardiac enzymes?

Enzymes are biochemical catalysts. In other words, enzymes are proteins""large molecules made of amino acids that are necessary to the body's structure, function, and regulation""that help chemical reactions take place. Cardiac enzymes are found in heart tissue, and they serve as catalysts for the heart's various biochemical reactions. Key cardiac enzymes are Troponin and Creatine Phosphokinase (CPK).

What are the names of some cardiac enzymes and what do they do?

Troponin is a particularly important cardiac enzyme, because it plays a central role in how heart muscles contract. Troponin controls how the heart muscle responds to the signal received for contraction, and it regulates the force with which the muscle contracts. Creatine phosophokinase is also important, for it gives needed energy for movement by the heart.

So, why are cardiac enzymes important and what can they tell us?

In the case of a blocked artery (i.e., heart attack), heart surgery, or any type of heart injury, the flow of oxygen-rich blood to the heart is interrupted""damaging the heart and its muscles. Using a heart attack as an example, a coronary artery, which is an artery that supplies blood to the heart, is completely blocked by a blood clot, and the heart is deprived of oxygenated blood. When heart muscle is damaged in the case of a heart attack, high concentrations of cardiac enzymes are released into the blood stream.



Death or damage to heart muscle cells leads to disintegration of heart cell membranes, which are the outer coats of muscles cells. Loss of cell membranes results in a "leaking" of cardiac muscle enzymes into the blood""leading to high levels of cardiac enzymes in the blood after a heart attack or other heart damage.

For heart attacks, measuring the levels of cardiac enzymes in the blood is a common test for the diagnosis of a heart attack and the amount the damage done to the heart; the medical field considers the measurement of cardiac enzyme levels in the blood to be a reliable test for a heart attack.

About measuring cardiac enzyme levels

However, one should note that cardiac enzymes leak slowly into the blood, and unusually high levels of cardiac enzymes in the blood may not appear until six or more hours after the onset of a heart attack. Thus, if a person has chest pain but has normal levels of cardiac enzymes in the blood, a heart attack cannot be ruled out. In that instance, repeated cardiac enzymes tests are normally conducted to confirm diagnosis of a heart attack.

There are separate cardiac enzyme tests for Troponin and CPK. The CPK is considered the least accurate test because the CPK enzyme is found in the heart muscles, skeletal muscles, and the brain; as such, unusually elevated CPK enzyme levels in the blood stream can be attributed to a muscle injury. The Troponin test is considered the most accurate cardiac enzyme test in the diagnosis of a heart attack.

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