Myocardial Infarction

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Myocardial Infarction

Statistics of Myocardial Infarction in the United States

Affects 1/2 million people per year in the US

50% die before reaching the hospital

7-15% die during hospitalization

7-15% die during the following year

Table 1

Gender Specific Symptoms of MI
Male	A feeling of mid-sternal pressure and/or squeezing sensation with accompanying pain Pain radiating from midchest to shoulders, neck or arms Lightheadedness, fainting, sweating or dyspnea Suddent onset of rapid heartbeats
Female	Angina that manifested by chest tightness that radiates down the left arm or into the jaw Breathlessness (chronic) Chronic fatigue (severe) Dizziness Edema of lower ankles/lower legs Fluttering or rapid heartbeats Gastric upset or nausea

General Signs of MI

Pale and anxious. May be diaphoretic

Mild to moderate increase in heart rate. People with MI's involving the inferior wall may have bradycardia

Increased blood pressure unless shock is present

New systolic murmur may appear

Friction rub common in patients who have involvement of the entire myocardial wall

Table 2

DIAGNOSIS OF MYOCARDIAL INFARCTION
Q-wave MI	Non Q-wave MI
History - Signs - Symptoms
ECG Acute inferior, anterior, lateral transmural MI ST segment elevation T wave upright As pathologic Q wave develops, T wave inverts Acute posterior transmural MI (mirror image of anterior wall) ST segment depression T wave inverted As pathologic Q wave develops, T wave becomes upright	ECG T wave becomes symmetrically inverted indefinitely ST segment depression for several days R wave normal No Q wave develops
Cardiac Enzymes CK-MB (gold standard) Troponin - cTnT & cTnI high specificity for heart muscle Myoglobin AST & LDH (low specificity)
Laboratory Testing (reserved for dx or tx problems) Echocardiography Radionuclide Scanning Technetium pyrophosphate Thallium-201

Objectives

Case Study

Clinical Course

ABGs

CBC

Blood Chemistry

Quiz