cardiac Flashcards
non modifiable risk fx heart disease
age, male, family history
modifiable risk fx heart disease
smoking, htn, diet, hyperlipidemia, physical inactivity, obesity DM, pvd, l ventricular wall motion dysfunction
majority mis caused by
atherosclerosis
patho MI
emoli–>ischemia–>acidosis–>inflammatory/cellular response–>preservation measures (collateral circ)–?zones of necrosis—>signs of MI
ami caused by
ruptured plaque emboli lodging in a coronary vessel
cessation of perfusion causes
aerobic production (38 ATP) to anaerobic (2ATP)
ischemia occurs when
ATP deman is greater than atp production
myocardial acidosis
first 6 hours of onset mi symptoms:
- H+accumulate
- ca++ displace from SR
- K= shift outside cell and NA+ inside, altered cell membrane action potential causing edema and arrhythmias
- myocardial acidosis
anerobic waste leads to
lactic acide, increased intracellular ph and inhibition of anaerobic atp production
continued hpoxia leads to
cell death and necrosis
necrotic myocardial cells release
cytokines that mediate acute inflamm process
what accumulates at infarct site- proteolytic enzymes that spills proteins into smaller peptides
this exacerbates injury
myocardial o2 reserve is gone within
8 seconds
immediaely after total occlusion how many normal heartbeats can be completed
sufficient o2 and atp in tissue to sustain 27
ecg changes in
30 seconds
pain with mi
60 seconds after ischemia
myocardial cells are irreversibly injured after
30-40 minutes of ischemia
zone of necrosis
center, contains dead tissue
zone of injury
inner ring- tissue cannot contract but not necrotic
zone of ischemia
inner and outer ring, superimposed upon the zone of injury, separates the other two zones from undamaged tissue
effects of MI
decrease ventricular stroke volume—> decreased CO
- increased LV filling pressure
- decreased cardiac output—> decreased compliance left ventricle= resultant stiff muyocardiam increases BP
- decreased CO and arterial pressure–> baroreceptor mediated
- pain stimulates vasoconstriction and HTN
- SNS increases o2 demand, enlarging the infarcted region and preciptating arrhythmias and impairing cardiac function
s/s AMI
substernal chest pain
progressing hypoxia
dizziness, nausea
itachycardia, increased resp and dyspnea
class i nyh assoc
no limit physical activity
class II (mild)
slight limitation activity, physical activity leads to fatigue, dyspnea, palpitation