Lipp Vis Nursing ChaptLWBK1630_C02_p013-068

Chapter 2 • Cardiovascular Care  33

Effects of Ischemia, Injury and Infarction on an EKG Recording

Ischemia causes inversion of the T wave because of altered repolarization. Cardiac muscle injury causes elevation of the ST segment. Later Q waves develop because of the absence of the depolarization current from the necrotic tissue and opposing currents from other parts of the heart. (Reprinted with permission from Hinkle JL, Cheever KH. Brunner & Suddarth’s Textbook of Medical-Surgical Nursing . 13th ed. Philadelphia: Wolters Kluwer; 2013.)

T

PICTURING PATHO

Zone of ischemia

R

T

ST

Q

Zone of injury

Q

Zone of infarction

Endocardium

Myocardium

Epicardium

Comparing Signs and Symptoms of Angina and MI

Angina

Myocardial Infarction

• Pressure, heaviness, squeezing, constriction, choking, burning, tightness (knot in throat or chest), rather than pain (sharp, stabbing, pins and needles-like).

• Severe, diffuse, steady substernal pain; described as pressure-like, squeezing, or dull.

Char ac ter, Location, and Radiation

• 2–5 min

• More than 15 min

Duration of Pain

• Elicited by activities and situations that increase myocardial oxygen demand. • Gradual in onset and offset. • Physical activity, cold, emotional stress, sexual intercourse, meals, or lying down (which results in an increase in venous return and increase in wall stress). • Once present, it may be constant and does not change with position or respiration.

• Occurs spontaneously • May be sequela to unstable angina

Precipitating Events

• Rest, nitroglycerin, oxygen may be effective.

• Not relieved by rest or nitroglycerin but requires opioids (i.e., Morphine)

Relieving Measures

• Shortness of breath • Nausea • Diaphoresis • Belching • Nausea • Indigestion • Dizziness, • Lightheadedness, • Clamminess, • Fatigue

• Feeling of impending doom • Fatigue • Bradycardia • Tachycardia • Nausea, vomiting, hiccups • Shortness of breath • Dizziness

Associated Symptoms

• Palpitations • Anxiety, fear • Hypotension or hypertension • Palpable precordial pulse • Arrhythmias • Diaphoresis; cool, clammy skin; facial pallor

• Usually within normal range

• Elevated

Cardiac Biomarkers