Myocardial Infarction - Weber State University

[Pages:21]Myocardial Infarction

Symbree Minniear

Myocardial Infarction

? A myocardial infarction refers to the death of myocardial muscle cells that occurs when a substantial decrease or complete disruption of blood flow through a coronary artery deprives the downstream tissue of oxygen for an extended period.

? In an MI, an area of the myocardium is permanently destroyed and cannot be .



Epidemiology

? Approximately every 25 seconds, an American will have a coronary event, and approximately every minute, someone will die of one.

? Coronary heart disease caused 1 of every 6 deaths in the United States in 2008.

? About every 34 seconds, someone in the United States has a myocardial infarction.

Symptoms

? Pain is the most common symptom in patients' experience a MI.

? Pain can be experienced in your arms, shoulder, neck, teeth, jaw, abdomen, or back.

? It may feel like a tight band around the chest, bad indigestion, like something is sitting on your chest, or squeezing.

? Undue fatigue ? Palpitations ? Dyspnea ? Anxiety ? Cough ? Fainting ? Light-headedness,

dizziness ? Nausea or vomiting ? Profuse sweating ? Confusion

Laboratory Diagnosis

? Blood analysis can be performed to determine whether tissue damage has occurred to the myocardium. Polymorphonuclear leukocytes and erythrocyte sedimentation rates are both indicative of myocardial damage.

? Myocardial injury can also be recognized by the appearance of various cardiac biomarkers that are released when the myocardial walls lose their integrity.

Biochemical markers such as troponin (I and T), creatinine kinase (CK) and its isoenzyme CK-MD, and lactate dehydrogenase (LDH).

Tests and Evaluation

? Electrocardiography (ECG):

Patients presenting with an acute transmural MI have ECG changes that include hyperpolarization of the T waves and ST-segment elevation.

Patients experiencing a subendocardial MI typically demonstrate ST-segment depression.

? Echocardiography:

Provides information regarding wall motion and blood perfusion.

Two-dimensional echocardiography is used to visualize the left ventricular walls and assess the amount of movement.

Tests and Evaluation

? Multiple-gated analysis (MUGA): Uses technetium-99m stannous pyrophosphate, which tags to red blood cells. By imaging tagged red blood cells wall motion and ejection fraction can be assessed.

? Computed tomography (CT) and magnetic resonance imaging (MRI): May also be used to assess ventricular wall motion.

? Radionuclide imaging: Are used to assess either blood flow defects or wall motion abnormalities.

Complications

? Arrhythmias can occur if the myocardium is damaged due to an MI.

? Depending on the amount of damaged tissue the heart may not be able to adequately pump blood to the body, which may lead to heart failure.

? Areas of heart muscle weakened by a heart attack can rupture, leaving a hole in part of the heart.

? Heart valves damaged during a heart attack may develop severe, life-threatening leakage problems.

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