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9.16 Angina and Non-lethal Ischemia
8am by Dr. Vander Heide
17
Pathology
Professional
09/19/2011

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Cards

Term
When does coronary artherosclerosis become symptomatic?
Definition
when 70% of the lumen is occluded
Term
blood flow =
Definition
(perfusion pressure)/ (R due to clot + R due to vessels)
*resistances are in series; heart compensates for resistance from clot by vasodilating i.e. reducing vessel resistance
Term
When does coronary artherosclerosis become symptomatic AT REST?
Definition
with severe obstruction such as more than 90% of the vessel
Term
How long can the heart use creatine phosphate and ATP stores once there is ischemic event?
Definition
first 30 seconds of normal contractile activity. With SEVERE ischemia, creatine phosphate is depleted within a few seconds
Term
In canine myocardial ischemia studies, ATP decreases to _% of control by 15 minutes and _% of control after 40 minutes.
Definition
35%, less than 10%
Term
Does the heart produce or extract lactate from the blood?
Definition
normally extracts but during ischemia heart is net producer of lactate
Term
How many ATP does anaerobic glycolysis produce? oxidative metabolism?
Definition
2 vs. 38
Term
Even under conditions of maximal stimulation, anaerobic glycolysis can produce __% of the HEP necessary for a normal working heart.
Definition
7
Term
What effect on shortening does a decrease in blood flow from 1-70% have?
Definition
parallel decrease in shortening (hypokinesis)
Term
What effect on shortening does a decrease in blood flow of 80% have?
Definition
akinesis (no shortening)
Term
What effect on shortening does a decrease in blood flow of more than 90% have?
Definition
dyskinesis (paradoxical lengthening)
Term
WHat is the mechanism behind the decrease in blood flow effect on shortening of cardiac myocytes?
Definition
not well defined. Definately NOT the result of HEP depletion but might be due to alterations in intracellular calcium handling, developing intracellular acidosis and accumulation of fatty acids (lipid breakdown)
Term
T/F Myocardial ischemia affects the normal function of the heart during diastole.
Definition
true: ischemia impairs relaxation and makes the ventricle stiffer which impairs ventricular filling and further impairs cardiac output
Term
What is myocardial stunning?
Definition
prolonged yet reversible systolic dysfunction of the heart following a period of ischemia
Term
Clinically, myocardial stunning most likely occurs in patients who...
Definition
subsequent to ischemic cardiac arrest (during surgical/bypass procedures), following thrombolysis during an acute myocardial infarction (affects the viable myocardium adjascent to the infarcted tissue), following therapeutic ballooon angioplasty, or in pts with vasospastic angina and/or unstable angina
Term
What is myocardial hibernation?
Definition
chronic mechanical dysfunction (wall motion abnormality) subsequent to chronic,severe ischemia (i.e. high grade coronary stenosis) The wall motion abnormality is restored to normal upon restoration of blood flow
Term
Compare and contrast myocardial stunning versus myocardial hibernation.
Definition
in myocardial stunning there is mismatch between flow and function for a period of days while blood flow and function are matched for myocardial hibernation. However there is no irreversible injury/necrosis associated with EITHER sutnning or hibernation; they are functional deficits
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