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76 Cards in this Set

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occurs when one of the coronary arteries becomes totally occluded
myocardial infarction
(heart attack)
In the presence of underlying atherosclerotic plaque, the sudden total occlusion that precipitates infarction is usually due to superimposed ______ or ______.
thrombosis

coronary artery spasm
three components to the diagnosis of MI
(1) History and Physical Exam
(2) Cardiac Enzymes
(3) EKG
classical physical exam presentation of MI
prolonged, crushing substernal chest pain radiating to the jaw or left arm associated with nausea, diaphoresis, and shortness of breath
What patients are especially prone not to manifest all or any symptoms of AMI?
diabetics and the elderly
infaction that is not associated with any overt clinical manifestations at all
"silent" MI
True or False:
Dying myocardial cells leak their internal contents into the bloodstream.
True.
CK stands for
creatine kinase
What is MB?
It is an isoenzyme of creatine kinase (CK-MB) that is strongly indicative on an infarction when present in the blood.
a critical enzyme in the evaluation of suspected MI because it rises earlier than the CK-MB isoenzyme
Troponin I
How long may Troponin I levels remain elevated in the blood?
several days
How long after an MI do CK levels usually rise?
6 hours
How long does it take CK levels to return to normal?
within 48 hours
True or False:
In most MIs, the EKG alone is insufficient to reveal the correct diagnosis.
False.
In most infarctions, the EKG will reveal the correct diagnosis.
How long after MI onset does it take for characteristic changes to appear on EKG?
almost immediately
True or False:
Initial EKG is virtually always difinitive in diagnosing MI.
False.
Initial EKG may not always be diagnostic, and the evolution of EKG changes varies from person to person; thus, it is necessary to obtain serial cardiograms once the patient is admitted.
Three EKG stages during MI:
(1) T wave peaking and inversion

(2) ST segment elevation

(3) appearance of new Q waves
With the onset of infarction, T waves become tall and narrow, a phenomenon called _____.
peaking
Peaked T waves in MI are often referred to as ______ T waves.
hyperacute
A few hours after T wave peaking, T wave _______ typically ensues.
inversion
How long after T wave peaking does T wave inversion typically occur?
a few hours
The pattern of T wave peaking and inversion in suspected MI reflects this myocardial condition.
ischemia
another term for lack of adequate blood flow
ischemia
True or False:
Ischemia associated with T wave peaking and inversion is reversible.
True.
What will usually happen to peaked/inverted T waves if blood flow to the ischemic tissue is restored?
the T waves will revert to normal
What will happen to T waves if actual myocardial cell death has occurred?
T wave inversion will persist for months to years.
True or False:
T wave inversion indicates true infarction.
False.
T wave inversion is indicative only of ischemia and is not diagnostic of myocardial infarction.
True or False:
T wave inversion is specific to AMI.
False.
T wave inversion is a very non-specific finding.
What is the chief difference between a myocardial ischemia T wave and T waves in other circumstance (such as ventricular hypertrophy).
Myocardial ischemia T waves tend to be more symmetrical.
In patients whose T waves are already inverted, ischemia may cause them to revert to normal, a phenomenon called _____.
pseudonormalization
Following T wave peak and inversion, this is the second change that occurs acutely in the evolution of an infartcion.
ST segment elevation
ST segment elevation signifies myocardial ______.
injury
a degree of cellular damage beyond that of mere ischemia, but potentially reversible
myocardial injury
True or False:
In most cases, ST segment elevation indicates that only injury has occurred, but not yet infarction.
False.
In most cases, ST elevation is a reliable sign that true infarction has occurred and that further EKG changes will evolve.
True or False:
By the time ST segment elevation occurs, therapeutic intervention is largely futile.
False.
Further EKG changes will evolve unless there is immediate and aggressive therapeutic intervention.
Even in the setting of a true infarction, ST segments usually return to baseling within this time frame.
within a few hours
Persistent ST segment elevation (not returning to normal within a few hours of infarction) often indicates this condition.
ventricular aneurysm
(weakening and bulging of the ventricular wall)
True or False:
ST segment elevation can be seen in a number of conditions besides myocardial injury.
True.
Name the type of ST segment elevation that can be seen in normal hearts.
J point elevation
or
"early repolarization"
(misnomer)
place where the ST segment takes off from the QRS complex in J point elevation
J point
or
junction point
True or False:
J point elevation is almost always indicative of a sick heart.
False.
J point elevation is common in young, healthy individuals. It has no pathological implications whatsoever.
In J point elevation, the ST segment usually returns to baseline with ______.
exercise
How can the ST elevation of myocardial injury be distinguished from that of J point elevation?
Myocardial injury ST elevation tends to be bowed upward (convex upstroke), merging imperceptibly with the T wave.

In J point elevation, the T wave maintains its independent waveform (concave upstroke).
After the ST segment has returned to baseline, what is the next EKG development that one would expect to confirm true infarction?
new Q waves
The appearance of new Q waves indicates that what has occurred?
irreversible myocardial cell death
True or False:
The presence of new Q waves can indicate nothing more than ischemia.
False.
The presence of Q waves is diagnostic of myocardial infarction.
How long after infaction does it take for Q waves to appear?
several hours to several days
How long do Q waves tend to persist after the infarction?
for the life of the patient
Why do Q waves form?
All electrical forces are directed sharply AWAY from infarcted tissue, which manifests in a deep negative first-deflection in the affected lead. Under normal conditions, only AVR would show cardiac depolarization moving sharply away from the lead in this way.
True or False:
The depolarization wave still passes through infarcted tissue.
False.
When a region of the myocardium dies, in becomes electrically silent -- it is no longer able to conduct an electrical current.
Opposing changes seen by leads distant to the site of the infarction are called ______.
reciprocal changes
True or False:
Leads located some distance from the site of an infarction will see an apparent increase in the electrical forces moving toward them.
True.
True or False:
Reciprocity in distant leads applies to Q waves as well as ST segment and T wave changes.
True.
True or False:
A lead distant from the site of the infarction may show ST depression.
True.
This would represent a reciprocal change from an infarction in the area of an opposing lead.
Under what conditions is ST depression likely to occur in MI.
(1) reciprocal changes in distant leads

(2) non-Q wave infarctions
True or False:
Small Q waves are a normal finding.
True.
(less than 1 mm)
In which leads do small Q waves typically appear in perfectly normal hearts.
left lateral leads and
occassionally inferior leads
In normal hearts, what are small Q waves caused by?
early left-to-right septal depolarization
term used for Q waves that signify infarction
significant Q waves
How do significant Q waves differ from normal Q waves in appearance?
significant Q waves tend to be wider and deeper
criteria for calling a Q wave significant
(1) greater than 0.04 seconds in duration

(2) depth of at least one third the height of the corresponding R wave
True or False:
AVR normally has a deep Q wave.
True
Which lead should not be considered when assessing an infarction?
AVR
(normally has deep Q waves)
condition characterized by unstable coronary disease or an evolving infarction in which emergent therapy can prevent additional damage and possibly even be life-saving
acute coronary syndrome
What is the most critical factor in dealing with acute coronary syndrome?
early detection of AMI
widely available therapies that can prevent the completion of an infarction and improve survival
thrombolytic therapy
emergency angioplasty
to lyse a clot as an emergency intervention to AMI
thrombolysis
(thrombolytic therapy)
common thrombolytic agents
streptokinase
anisoylated plasminogen activator complex
tissue plasminogen activator (tPA)
emergency angioplasty should take place within how many hours of the onset of infarction
six hours
stents coated with these drugs may prevent reocclusion as a result of cell proliferation
cytotoxic drugs
Cytotoxic drug-coated stents has reduced the rate of restenosis from about one third of angioplasty patients to ______.
virtually none
True or False:
EKG is one of the very few diagnostic skills that can immediately save lives.
True.
In which leads do the characteristic changes of infarction occur?
only in those leads overlying or near the site of the infarction
True of false:
Characteristic changes of infarction occur in all leads.
False.
They occur only in those leads overlying the site of the infarctions.
Under what conditions is ST Segment elevation likely to be seen in ischemic heart disease?
with an evolving transmutal infarction or with Prinzmetal's angina
Under what conditions is ST Segment depression likely to be seen in ischemic heart disease?
with typical angina, with a non-Q wave infarction, or as reciprocal changes in infarction.