Evans Flashcards
preconditioning definition
short period of ischemia improves the hearts ability to tolerate longer periods of ischemic insult
do VAA produce preconditioning effect?
yes, protects the myocardium from ischemia and reperfusion injury and reducing infarct size
should VAA be used in hemodynamically stable cardiac surgery patients?
yes, means of reducing myocardial damage and death
hibernation
self-preservation mechanism whereby left ventricular contractile function is reduced to match the amount of O2 available
less BF less contraction
left ventricular perfusion-contraction matching results from:
stable coronary plaques cause chronic reduction in coronary perfusion, and steady-state ischemia occurs
this is part of hibernation
how does CABG relate to hibernation?
significantly improved HF after CABG
ischemic myocardium considered viable
20-40% pts have significant improvement
cardiac stunning
brief periods of ischemia lasting less than 20 minutes
reversible contractile dysfunction
in cardiac stunning, does necrosis occur?
no
how long can reversible contractile dysfunction (stunning) last?
several hours
after CPBP & cardiac stunning, how long is inotropic support needed?
12-24 hours
supply ischemia causes increase in _____ and a decrease in _______
increase in ventricular compliance (dilation)
decrease in contractility
demand ischemia reduces _____ and effects contractility _______
reduces compliance (stiffening), without impacting contractility
primary characteristics of remodeling are: (3)
hypertrophy or dilation
myocyte death
increased interstitial fibrosis
clinical impact of ventricular hypertrophy:
change in systolic and diastolic function
concentric ventricular remodeling: (pressure or volume)
pressure overload
eccentric ventricular remodeling: (pressure or volume)
volume overload
supply ischemia (from MI or chronic volume overload) causes what type of hypertrophy?
eccentric, dilation
in eccentric hypertrophy, what happens to chamber size?
chamber size increases in attempt to preserve stroke volume (wall is thinner)
what shape does heart become in dilated state?
spherical
how does the body compensate for reduced SV?
SNS stimulation to increase HR
Systolic heart failure is caused by:
CAD
dilated cardiomyopathy
chronic volume overload
chronic hypertension
can pulmonary congestion develop with a normal EF?
yes
can symptoms of heart failure develop with normal EF?
yes
diastolic HF is often called:
HF with preserved EF (greater than 40%)
