Acute Coronary Syndromes Flashcards
Acute Coronary Syndromes (ACS) in the US
How many Americans a year have an MI? How many will die from a MI?
- 750,000 americans
- 116,000 will die (about 15%)
Acute Coronary Syndromes (ACS) in the US
Heart disease accounts for 1 in ?? deaths in U.S., killing over 370,000 per year.
7 deaths
ACS
Describe the continuum of ACS.
- unstable angina
- Non-ST-elevation MI (NSTEMI)
- ST-elevation MI (STEMI)
- 1 and 2 and due to partially occlusive intracoronary thrombus.
- 3 is due to totally occlusive intracoronary thrombus
ACS
What are both Unstable Angina (UA) and Non-ST elevation myocardial infarction (NSTEMI) caused by?
partially occlusive intracoronary thrombus from plaque rupture
ACS
What is it called when a partially occluded intracoronary thrombus causes some necrosis?
NSTEMI
ACS
What is it called when a partially occluded intracoronary thrombus causes no necrosis?
UA
Acute Myocardial Infarction: STEMI
Coronary thrombosis results from plaque rupture with superimposed:
- rapid platelet aggregation (clumping at site of rupture)
- vasoconstriction: stimulated by the release of thromboxane A2 from platelets
- formation of intracoronary fibrin clot
Acute Myocardial Infarction: STEMI
What percentage of acute STEMI are due to acute vasospasm?
10%
Normal Hemostasis
What are the 3 primary steps in normal hemostasis?
- vasoconstriction of the blood vessel
- platelet plug
- blood coagulation
Normal Hemostasis
What is the purpose of vasoconstriction?
to reduce blood flow and prevent blood loss
Normal Hemostasis
What are the main secreting cells that stimulate vasoconstriction?
endothelial cells and platelets
Normal Hemostasis
What triggers the vasoconstriction in blood vessels?
reduced nitric oxide bioavailability
Normal Hemostasis
What is a platelet plug?
temporary blockage of bleeding
Normal Hemostasis
What portion of hemostasis is the platelet plug considered?
primary hemostasis
Normal Hemostasis
What is blood coagulation?
formation of a clot that seals the hole until tissues are repaired
Normal Hemostasis
What portion of hemostasis is blood coagulation considered?
secondary hemostasis
Normal Hemostasis: Primary
Define Primary hemostasis.
1st line of defense against bleeding which occurs within seconds
Normal Hemostasis: Primary
Describe the general first 4 steps of primary hemostasis.
a. endothelial surface of blood vessel damaged
b. platelets become activated
c. formation of platelet plug
d. Thromboxane (TXA2) causes vasoconstriction
Normal Hemostasis: Primary
What does the exposure of the subendothelium collagen attract? Why?
- platelet attraction and adhesion
- collagen is very thrombogenic
Normal Hemostasis: Primary
After adhesion to subendothelium collagen, what do platelets begin to release? What does this cause?
- release ADP and fibrinogen
- causes aggregation of platelets
Normal Hemostasis: Primary
What do the aggregated platelets become at the site of the vessel injury?
the platelet plug
Normal Hemostasis: Primary
How does thromboxane (TXA2) prevent blood loss?
inducing vasoconstriction
Normal Hemostasis: Secondary
How long does it take for secondary hemostasis to occur?
within hours
Normal Hemostasis: Secondary
What are the 3 general steps of secondary hemostasis?
a. subendothelial tissue factor
b. formation of a fibrin clot
c. tissue plasminogen activator (tPA)
Normal Hemostasis: Secondary
What activates plasma coagulation pathways when exposed?
subendothelial tissue factor
Normal Hemostasis: Secondary
What is the purpose of a fibrin clot formation?
stabilization and strengthening of platelet plug
Normal Hemostasis: Secondary
What cell type produces tPA?
endothelium
Normal Hemostasis: Secondary
What is the purpose of tPA?
dissolving the fibrin clot via the enzyme plasmin after injury becomes healed
Tissue Factor (Extrinsic) pathway
Step 1: Trauma (plaque rupture) causes ?? to become exposed.
tissue factor
Tissue Factor (Extrinsic) pathway
Step 2: Tissue factor converts ?? into ??.
- factor X
- factor Xa
Tissue Factor (Extrinsic) pathway
Step 3: Factor Xa activates enzyme ?? to form ??.
- prothrombin
- thrombin
Tissue Factor (Extrinsic) pathway
Step 4: Thrombin converts ?? to ??.
- fibrinogen
- fibrin
Tissue Factor (Extrinsic) pathway
Step 5: Fibrin is crucial for the formation of ??.
cross-linked clot
Tissue Factor (Extrinsic) pathway
During normal hemostasis, the process concludes with lyses by which enzyme? What activates this enzyme?
- plasmin
- tissue plasminogen activator (tPA)
Tissue Factor (Extrinsic) pathway
Why is normal lyses ineffective during a plaque rupture?
tPA is overwhelmed and cannot keep up with the clot formation
Possible Symptoms of Acute MI
List any symptoms that can be solo or in combination with any other:
- angina
- dyspnea
- diaphoresis
- pallr
- hypotension
- syncope or pre-syncope
Two important points of acute MI
Up to 25% of patients have ?? during MI.
no symptoms
Two important points of acute MI
?? are more common to have atypical symptoms that go unrecognized.
Women
What are the 3 Goals of Acute MI Therapy?
- restore balance of myocardial oxygen supply/demand
- pain relief
- prevent complications that may arise post-MI
Goals of Acute MI Therapy
How can the balance of mycardial demand/balance be restored?
reduction of ischemia by increasing supply of demand of MVO2
Goals of Acute MI Therapy
What type of pain relief is the main focus?
reduction of angina symptoms
Goals of Acute MI Therapy
What type of complications can be prevented post MI?
- re-infarction
- dangerous arrhythmias
- congestive heart failure
- death
