MI & Angina Flashcards
What is the definition of a myocardial infarction?
Occurs when one of the coronary arteries becomes totally occluded, so the region of the heart supplied by that artery loses its blood supply and dies due to lack of oxygen and other nutrients
What generally causes the progression to infarction?
Progressive narrowing of the coronary arteries by atherosclerosis with superimposed thrombosis or spasm of the coronary artery
What kind of patients commonly present atypically?
Elderly, diabetics, and females may be atypical and up to 1/3 are silent
Name the changes in an EKG during an acute MI. Which need to be present together?
http://click.email.thinkgeek.com/?qs=ba1d7a3825e7e48aff7a0979c0dd29ee2e1e7691e2cc16882cad0a1c598cfa0b 1) T wave peaking followed by T wave inversion
2) ST segment elevation
3) Appearance of new Q waves
In 2 or more leads, any can be present without another!
1) T wave peaking followed by T wave inversion
2) ST segment elevation
3) Appearance of new Q waves
In 2 or more leads, any can be present without another!
At the onset of the MI how do T waves generally appear?
hyperacute T waves, a few hours later they invert
What do T wave changes reflect? Are they reversible?
Reflect ischemia, Reversible if flow restored or oxygen demands decreased
If actual cell death (infarction) has occured how long will T wave inversion persist for?
Months to years
What is psedunormalization?
Patients who already have inverted T waves, ischemia may cause them to become normal
Are ischemic T wave inverted symmetricly or asymmetricly?
symmetrically
What does ST segment elevation signify? Is this reversible?
Injury. Still reversible but requires immediate and aggressive intervention
How long does it take for ST segments to return to normal?
A few hours
Persistent ST segment elevation indicates?
formation of a ventricular aneurysm
What is ST segment elevation called in normal healthy hearts?
Early repolarization of J point elevation
How does the elevated ST segment of MI look different for the J point elevation?
In J point elevation, the T wave maintains its independent waveform. In MI, ST segment is bowed upward and tends to merge with the T wave.
What do Q waves indicate?
Irreversible cell death, are diagnostic of MI
When do Q waves form during MI and how long do they stay?
Usually appear several hours after onset of infarction but may take days to evolve. ST segment has usually already returned to baseline. Q waves usually stay for the lifetime of the patient.
An electrode overlying the infarct will record a _________ Q wave
Deep negative deflection
Electrodes in distant leads to the infarct will record ______ R waves and possible________ ST segments
tall positive R waves and depressed ST segements
What lead can not be used to diagnose MI with a Q wave?
aVR, normally has a deep Q wave
In normal hearts, small q waves can be seen in what leads?
Left lateral ( I, aVL, V5, V6) and sometimes inferior leads (especially II and III)
Significant Q waves must be:
Greater than 0.04 seconds (1 small block) duration and depth of q wave must be atleast 1/3rd height of the R wave
Inferior infarcts usually caused by occlusion of the
right coronary artery or its descending branch
An 85 year old women presents to the ED with chest pain. Her EKG shows T wave inversion and ST segment elevation. Her troponins are elevated. You quickly send her to cath lab but it is determined she has no coronary artery disease. What is your diagnoses?
Apical Ballooning Sydrome
What is typical angina described as?
Dull, burning, or boring substernal pressure or heaviness, typically worse with exertion or stress, relieved by rest and nitroglycerin
