1. ACUTE CORONARY SYNDROMES
Patricia Zdan, RN, CCRN
November 25, 2002

2. Major Syndromes Unstable Angina Non-Q Wave MI Q Wave MI
Patients presenting with ischemic chest pain represents a continuum of a similar disease processclassified as acute coronary syndromes.

3. Pathophysiology Obstruction by atherosclerotic plaque
Hemorrhage into a plaque
Embolism caused by thrombi or atheromatous material
Coronary spasm
This is a coronary artery with atherosclerotic plaques. There is a hemorrhage into the plaque.
Plaque disruption activates platelet adhesion, fibrin clot formation, and coronary thrombus.
Thrombus is the primary determinant in the acute blockage of coronary artery.
Coronary spasm as a primary cause is rare, except in cocaine abusers.

4. Ischemic Changes in Myocardial Tissue
Zone of ischemia
Zone of injury
Zone of infarction
Zone of ischemia composed of viable cells;
EKG evidence seen as inverted T
waves;
impaired repolarization of cells is
cause of many dysrhythmias
associated with MI
Zone of injury surrounds infarcted zone;
potentially viable tissue;
EKG evidence seen as ST segment
elevation
Zone of infarction is area of cellular death and
muscle necrosis in myocardium;
EKG evidence seen as pathologic
Q or QS wave

5. Collateral Circulation
When a patient has a blockage in a major coronary artery, small arterial anastomoses grow over time to help compensated for the loss of circulation.

6. Diagnosis Ischemic-type chest discomfort EKG changes
Rise and fall in serum cardiac markers
World Health Organization definition ---
Diagnosis of MI is based on presence of at least two of the following three criteria
Clinical history of ischemic-type chest pain
Changes on serially obtained EKG tracings
Rise and fall in serum cardiac markers

7. Clinical Presentation
Classic symptoms
Chest discomfort
Radiation
Associated symptoms
Atypical symptoms
Elderly
Diabetics
Women
Classic symptoms:
Dull, substernal discomfort described as pressure or tightness
Radiation to left arm, neck or jaw
Shortness of breath, palpitations, diaphoresis, nausea, vomiting
Atypical symptoms:
SOB, syncope, lightheadedness, indigestion, atypical chest pain

8. Pain Angina or infarction Focused pain history
Stable angina – symptoms exacerbated by activity; relieved by rest and NTG
Unstable angina – symptoms occur unpredictably, are more intense, last longer, or radiate to a different location than usual; occur at rest or during sleep; not always relieved by rest or NTG
MI – worst pain ever experienced; sense of impending doom; unrelieved by rest or NTG
“OLDCART”
Onset, location, duration (how long, intermitttant or consistant), characteristics (pressure, tightness, heaviness), accompanying symptoms, radiation, treatment

9. EKG Criteria
ST-segment depression of 1 mm or more in two or more contiguous leads or T-wave depression indicates myocardial ischemia
Ischemia occurs when coronary artery vasospasms decrease oxygen supply to the myocardium
Usually a transient, reversible event that's corrected when the blood and oxygen supply is restored to the myocardium
Prolonged ischemia can lead to injury

10. EKG Criteria
ST-segment elevation of 1 mm or more above the isoelectric line in two or more contiguous leads indicates myocardial injury
Indicates impaired blood flow through the coronary artery from vasospasm or thrombus development
Reflects an acute injury to the heart muscle and requires immediate treatment to reestablish blood flow to the myocardium before infarction occurs
With rapid treatment, injury may be reversible

11. EKG Criteria
A pathologic Q wave indicates myocardial infarction has already occurred
A pathologic or significant Q-wave is greater than 0.04 sec in width and 25% the height of R wave
Will always be present on 12-lead EKG
A Q-wave MI, or transmural infarction, affects all 3 layers of heart wall – epicardium, myocardium, endocardium

12. Serum Biomarkers Myoglobin Creatine kinase (CK) and CK- MB
Troponin complex
Serum cardiac markers useful for cofirming diagnosis when patients present without ST-segment elevation; diagnosis is unclear; need to distinguish between USA and non-Q wave MI
Myoglobin found in cardiac and skeletal muscle
appears in serum in 1-3 hours
useful initial screening tool within 6 hrs
of pain onset if EKG not diagnostic
CK and CK-MB rise with MI after 6-8 hrs, peaks in
18-24 hrs
lacks specificity for cardiac muscle
Troponin T & I are cardiac specifc; elevation indicates myocardial injury or infarction;
rises within 4-6 hrs, peaks in hrs, returns to normal in 6-7 days

13. Immediate Management Oxygen Nitroglycerin Analgesia Aspirin
Beta-blockers
O2 indicated if sat < 90%; limits ischemic myocardial injury; in uncomplicated cases, little justification for continuing beyond 2-3 hrs
NTG recommended 1st hrs in patients with acute MI and CHF, persistant ischemia, HTN; continued use with recurrent angina or persistant pulmonary congestion
Reduces preload and afterload, dilates coronary arteries improving collateral flow to ischemic areas
MSO4 is drug of choice; 2-4mg q 5 min
ASA produces rapid clinical antithrombotic effect
Beta-blocker decreases myocardial O2 demand by antagonizing excess catecholamine state

14. Thrombolytic Therapy
Early reperfusion is gold standard for reducing mortality associated with MI
Mortality rate from MI has declined 24.5% since thrombolytic intervention began more than a decade ago.
Thrombolytics work to dissolve the clot by converting plasminogen to plasmin. Plasminogen is a substance the body secretes in response to injury to the heart wall, contributing to clot formation. Plasmin breaks down the fibrin mesh that holds the clot together.

15. Thrombolytic Process
Coagulation cascade is made up of a series of enzymatic reactions which promote build-up of insoluble fibrin. Almost immediately after initiation of the clotting process, the fibrinolysis pathway is activated. Central to this pathway is plasminogen. The various forms of t-PA (Activase, Retavase, TNKase) convert plasminogen to plasmin, which in turn degrades fibrin, the main component of the clot.

16. Healthy Heart Keep your heart healthy: Exercise Low cholesterol diet
Weight control
Smoking cessation
Blood pressure control
Blood glucose control in diabetics