Acute Coronary Syndrome Flashcards
accounts for the vast majority of patients with ischemic heart disease
coronary artery disease
predominant symptom of coronary artery disease
chest pain
how many % of patients with acute chest pain will have ACS
15%
of patients with ACS, approximately __% will have unstable angina
2/3
of patients with ACS, ___% will have AMI
1/3
rest angina
angina occuring at rest
prolonged, usually > 20 mins
new-onset angina
new-onset angina limits ordinary physical activity, such as walking 1-2 blocks;clibing 1 flight of stairs of performing lighter activity
increasing angina
previously diagnosed angina that has become distinctly more frequent, has longer duration; lower in threshold, limiting ability to walk 1-2 blocks or climb 1 flight of stairs of perform lighter activity
the left coronary artery divides into
left circumflex and left anterior descending branches
provides the main blood suply to the anterior and septal regions of the heart
left anterior descending branch
the circumflex branch supplies
some of the anterior wall and a lage portion of the lateral wall of the heart
the right coronary artery suplies
right side of the heart and perfusion to the inferior aspect of the left ventricle (through its continuation as the right posterior descending artery)
atrioventricular conduction system receives blood supply from
a. atrioventricular branch of the right coronary artery
b. septal perforating branch of left anterior descending coronary artery
posteromedial papillary muscle receives blood supply from
one coronary artery
usually right coronary artery
ischemia occurs when there is an imbalance between
O2 demand
and O2 supply
O2 supply is influence by
O2 carrying capacity of the blood
coronary artery blood flow
O2 carrying capacity of the blood is determined by the
- amount of hemoglobin present
2. O2 saturation
coronary artery blood flow is determined by
duration of diastolic relaxation of the heart
and peripheral vascular resistance
exercise-induced myocardial ischemia usually occur as a result of
fixed atherosclerotic lesions
ACS may be caused by
- secondary reduction in myocardial blood flow due to coronary arterial vasospasm
- disruption or erosion of atherosclerotic plaques
- platelet aggregation or thrombus formation at the site of an atherosclerotic lesion
secondary causes of myocardial ischemia are
- increased myocardial O2 demand ( fever, tachycardia, thyrotoxicosis)
- reduced blood flow ( hypotension)
- reduced O2 delivery (anemia, hypoxemia)
atherosclerotic plauqe forms through
repetitive injury to the vessel wal
main cellular elements in plaque development
smooth muscle cells
macrophages
predominant extracellular milleu of atherosclerotic plaques
lipids
plaque fissuring and rupture are affected by
composition and shape shear forces coronary arterial tone coronary arterial perfusion pressure movements of the artery in response to myocardial contractions
when plaque rupture occurs
what is released
potent thrombogenic substances that activate circulating platelets
platelet response involves
adhesion
activation
aggregation
platelet interactions with subendothelial adhesion molecular such as collagen, fibronectin, and laminin
binding of the glycoprotein IIb receptor to the subendothelial form of von Willebrand factor
Adhesion
release a tissue factor, which stimulates the conversion of prothrombin to thrombin
lipid-laden macrophages
platelet activators
thrombin
local shear forces
platelet secretin - adenosine diphoshate, thromboxane A2, serotonin - autostimulatory agonists of platelet activation
in the final common pathway of platelet aggregation this occurs
activated platelet glycoprotein IIb/IIIa receptors become cross-linked by
fibrinogen and von Willebrand factor
TIMI score for unstable angina includes
age 65 yr or older
3 or more traditional risk factors for coronary artery disease
prior coronary stenosis of 50% or more
ST segment deviation on presenting electrocardiogram
2 or more anginal events prior to 24 h
aspiin use within the 7 day prior to presentation
elevated cardiac markers
high likelihood of ACS history
- chest or left arm pain or discomfort
2. known history of coronary artery disease including myocardial infarction
examination of ACS
transient mitral regurgitation murmur
hypotension, diaphoresis, pulmonary edema, rales
ECG
new or presumably new, transient ST segment deviation
(>/= 1 mm)
or T wave inversion in multiple precordial leads
cardiac markers
elevated cardiac troponin I, troponin T or MB fraction of creatinine kinase
