CARDIAC ENZYME TEST – Definition, Purposes, Client Preparation, Procedure, After Care and Enzyme Study Interpretation (NURSING PROCEDURE)
Enzymes are special proteins that catalyze chemical reactions in living cells. Cardiac enzymes are organ specific enzymes that are present in high concentration in myocardial tissue. Tissue damage causes a reaction of enzymes from their intracellular storage areas. For example, myocardial infarction causes cellular anoxia, which alters membrane permeability and causes spillage of enzymes into the surrounding tissue. This leakage of enzymes can be detected by rising plasma levels.
DEFINITION
Cardiac enzymes are complex compounds that are found in all tissues and that speed up the biochemical reactions of the body. Damage to body tissue causes release of the enzymes from injured cells
PURPOSE
- To detect myocardial infarction
- It is used in clinical evaluation and electrocardiography studies to diagnosis myocardial injury
CLIENT PREPARATION
- Explain the procedure to the client
- Prepare the client for venipuncture
- Reassure the client, who is usually frightened and having chest pain and may also be in denial
- Do not give intramuscular injections or perform repeated venipunctures, if possible, until all the initial enzyme studies are completed
- Instruct the client about the need to repeat blood sampling
- Determine if alcohol or drugs that affect results have been ingested
DIFFERENT TYPES OF CARDIAC ENZYMES
- Myoglobin
- CK-MB (creatine kinase myocardial bound
- Troponin I
- AST (aspartate aminotransferase)
- LDH (lactate dehydrogenase)
PROCEDURE
- Place the client in comfortable position
- Place the tourniquet in a proper, if the tourniquet is in place too long, inaccurate result may occur
- A venipuncture is necessary to obtain 5-10 ml of blood in a red-topped tube
- Results of the enzyme levels will determinate need for admission to the hospital and emergency treatment
- Assay of CK-MB can be done in the emergency room, with results available within 20 minutes
AFTER CARE
- Remove the tourniquet
- Apply gentle pressure over the punctured site
- Place the collected blood in a correct specimen tubes
- Sent the blood to laboratory with proper labeling and request
- Replace the articles to the treatment room
- Record the entire procedure in a nurse’s record
ENZYME STUDY PREPARATION
- The enzyme most commonly used to detect myocardial infarction is creatine kinase (CK) and lactic acid dehydrogenase (LDH). CK is an enzyme found in the heart, brain and skeletal muscles. The CK isoenzymes include CK-MM, CK-MB and CK-MB
- Isoenzymes are the various forms of CK and LDH, identified only by a process known as electrophoresis. There are three isoenzymes of CK: CK-MM (skeletal muscle), CK-MB (myocardial muscle) and CK-BB (brain)
- Elevated CK-MB indicates myocardial damage. Elevation of CK-MB may occur within 4-6 hours and peaks 18-24 hours after the acute ischemic event
- There are five isoenzymes for LDH (numbered 1 to 5), of which only LHD1 and LDH2 are cardiac-specific
- If the serum concentration of LDH1 is higher than the concentration of LDH2, the pattern is said to have flipped, signifying myocardial necrosis. 80% of individuals demonstrate evaluates in LDH within 48 hours after myocardial infarction
