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76 Cards in this Set
- Front
- Back
occurs when one of the coronary arteries becomes totally occluded
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myocardial infarction
(heart attack) |
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In the presence of underlying atherosclerotic plaque, the sudden total occlusion that precipitates infarction is usually due to superimposed ______ or ______.
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thrombosis
coronary artery spasm |
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three components to the diagnosis of MI
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(1) History and Physical Exam
(2) Cardiac Enzymes (3) EKG |
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classical physical exam presentation of MI
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prolonged, crushing substernal chest pain radiating to the jaw or left arm associated with nausea, diaphoresis, and shortness of breath
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What patients are especially prone not to manifest all or any symptoms of AMI?
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diabetics and the elderly
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infaction that is not associated with any overt clinical manifestations at all
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"silent" MI
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True or False:
Dying myocardial cells leak their internal contents into the bloodstream. |
True.
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CK stands for
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creatine kinase
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What is MB?
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It is an isoenzyme of creatine kinase (CK-MB) that is strongly indicative on an infarction when present in the blood.
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a critical enzyme in the evaluation of suspected MI because it rises earlier than the CK-MB isoenzyme
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Troponin I
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How long may Troponin I levels remain elevated in the blood?
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several days
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How long after an MI do CK levels usually rise?
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6 hours
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How long does it take CK levels to return to normal?
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within 48 hours
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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. |
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How long after MI onset does it take for characteristic changes to appear on EKG?
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almost immediately
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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. |
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Three EKG stages during MI:
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(1) T wave peaking and inversion
(2) ST segment elevation (3) appearance of new Q waves |
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With the onset of infarction, T waves become tall and narrow, a phenomenon called _____.
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peaking
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Peaked T waves in MI are often referred to as ______ T waves.
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hyperacute
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A few hours after T wave peaking, T wave _______ typically ensues.
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inversion
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How long after T wave peaking does T wave inversion typically occur?
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a few hours
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The pattern of T wave peaking and inversion in suspected MI reflects this myocardial condition.
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ischemia
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another term for lack of adequate blood flow
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ischemia
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True or False:
Ischemia associated with T wave peaking and inversion is reversible. |
True.
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What will usually happen to peaked/inverted T waves if blood flow to the ischemic tissue is restored?
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the T waves will revert to normal
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What will happen to T waves if actual myocardial cell death has occurred?
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T wave inversion will persist for months to years.
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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. |
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True or False:
T wave inversion is specific to AMI. |
False.
T wave inversion is a very non-specific finding. |
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What is the chief difference between a myocardial ischemia T wave and T waves in other circumstance (such as ventricular hypertrophy).
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Myocardial ischemia T waves tend to be more symmetrical.
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In patients whose T waves are already inverted, ischemia may cause them to revert to normal, a phenomenon called _____.
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pseudonormalization
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Following T wave peak and inversion, this is the second change that occurs acutely in the evolution of an infartcion.
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ST segment elevation
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ST segment elevation signifies myocardial ______.
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injury
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a degree of cellular damage beyond that of mere ischemia, but potentially reversible
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myocardial injury
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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. |
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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. |
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Even in the setting of a true infarction, ST segments usually return to baseling within this time frame.
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within a few hours
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Persistent ST segment elevation (not returning to normal within a few hours of infarction) often indicates this condition.
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ventricular aneurysm
(weakening and bulging of the ventricular wall) |
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True or False:
ST segment elevation can be seen in a number of conditions besides myocardial injury. |
True.
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Name the type of ST segment elevation that can be seen in normal hearts.
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J point elevation
or "early repolarization" (misnomer) |
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place where the ST segment takes off from the QRS complex in J point elevation
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J point
or junction point |
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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. |
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In J point elevation, the ST segment usually returns to baseline with ______.
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exercise
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How can the ST elevation of myocardial injury be distinguished from that of J point elevation?
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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). |
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After the ST segment has returned to baseline, what is the next EKG development that one would expect to confirm true infarction?
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new Q waves
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The appearance of new Q waves indicates that what has occurred?
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irreversible myocardial cell death
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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. |
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How long after infaction does it take for Q waves to appear?
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several hours to several days
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How long do Q waves tend to persist after the infarction?
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for the life of the patient
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Why do Q waves form?
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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.
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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. |
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Opposing changes seen by leads distant to the site of the infarction are called ______.
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reciprocal changes
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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.
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True or False:
Reciprocity in distant leads applies to Q waves as well as ST segment and T wave changes. |
True.
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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. |
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Under what conditions is ST depression likely to occur in MI.
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(1) reciprocal changes in distant leads
(2) non-Q wave infarctions |
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True or False:
Small Q waves are a normal finding. |
True.
(less than 1 mm) |
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In which leads do small Q waves typically appear in perfectly normal hearts.
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left lateral leads and
occassionally inferior leads |
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In normal hearts, what are small Q waves caused by?
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early left-to-right septal depolarization
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term used for Q waves that signify infarction
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significant Q waves
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How do significant Q waves differ from normal Q waves in appearance?
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significant Q waves tend to be wider and deeper
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criteria for calling a Q wave significant
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(1) greater than 0.04 seconds in duration
(2) depth of at least one third the height of the corresponding R wave |
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True or False:
AVR normally has a deep Q wave. |
True
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Which lead should not be considered when assessing an infarction?
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AVR
(normally has deep Q waves) |
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condition characterized by unstable coronary disease or an evolving infarction in which emergent therapy can prevent additional damage and possibly even be life-saving
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acute coronary syndrome
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What is the most critical factor in dealing with acute coronary syndrome?
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early detection of AMI
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widely available therapies that can prevent the completion of an infarction and improve survival
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thrombolytic therapy
emergency angioplasty |
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to lyse a clot as an emergency intervention to AMI
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thrombolysis
(thrombolytic therapy) |
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common thrombolytic agents
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streptokinase
anisoylated plasminogen activator complex tissue plasminogen activator (tPA) |
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emergency angioplasty should take place within how many hours of the onset of infarction
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six hours
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stents coated with these drugs may prevent reocclusion as a result of cell proliferation
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cytotoxic drugs
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Cytotoxic drug-coated stents has reduced the rate of restenosis from about one third of angioplasty patients to ______.
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virtually none
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True or False:
EKG is one of the very few diagnostic skills that can immediately save lives. |
True.
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In which leads do the characteristic changes of infarction occur?
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only in those leads overlying or near the site of the infarction
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True of false:
Characteristic changes of infarction occur in all leads. |
False.
They occur only in those leads overlying the site of the infarctions. |
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Under what conditions is ST Segment elevation likely to be seen in ischemic heart disease?
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with an evolving transmutal infarction or with Prinzmetal's angina
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Under what conditions is ST Segment depression likely to be seen in ischemic heart disease?
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with typical angina, with a non-Q wave infarction, or as reciprocal changes in infarction.
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