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26 Cards in this Set
- Front
- Back
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What is the pathophysiology of ST depression on an EKG?
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With predominant subendocardial ischemia the resultant ST vector is directed toward the inner layer of the affected ventricle and the ventricular cavity. Overlying leads therefore record ST depression.
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What is the pathophysiology of angina?
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Normal coronary arteries can dilate to accommodate the needs of the myocardium during exercise or other stressful states.
Arteries narrowed due to atherosclerosis cannot dilate adequately to meet the demands of the working myocardium. When the myocardium is working with less oxygen and other nutrients the metabolic changes cause myocardial ischemia and leads to the ischemic cascade |
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What is the order of the ischemic cascade?
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cellular alterations
diastolic dysfunction systolic dysfunction decreased filling ST alterations angina |
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What evalution/work up should be done in a patient with angina?
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Estimate the 10 year coronary risk – using the Framingham risk score.
We need to get lab values, all his medicines, and history of smoking. evaluate the extent and severity of ischemia at rest and during stress. |
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What are the symptoms of chronic stable angina?
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pain comes with exertion and is relieved with rest
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Describe how an exercise stress test works
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Treadmill exercise test is the preferred method if patients can exercise to at least 85% of the maximum predicted heart rate; (200-age in yrs).
This allows to evaluate the exercise capacity, BP and HR changes along with symptoms and EKG changes. |
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When would an exercise stress test be contraindicated?
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If the EKG at rest has > 1 mm ST depression, then the changes on stress EKG are not specific for detection of ischemia.
When patients are unable to exercise |
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When exercise stress tests are contraindicated, what tests would you do?
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additional imaging has to be added-either nuclear myocardial perfusion imaging or echocardiogram are used.
pharmacological stress tests |
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Describe how a pharmacological stress test works
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A resting nuclear perfusion imaging study is performed using Thallium.
I.V Adenosine will be given which causes the normal coronaries to dilate; diseased coronaries with stenosis cannot dilate. If diseased, nuclear isotope given is unequally distributed in the myocardium based on the coronary blood flow. The resting images are compared to the post Adenosine images to detect extent and location of decreased perfusion, or myocardial scar (MI) |
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Describe how a dobutamine stress echocardiogram works
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Resting echocardiogram is done.
Then increasing doses of Dobutamine is given as infusion. EKG, BP and echocardiogram will be performed during the infusion. EKG changes, symptoms and wall motion abnormalities on echocardiogram are evaluated to detect stress induced wall motion abnormalities |
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Describe indications and contraindication for a coronary angiogram
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Indications-extent and severity of the defects is suggestive of significant disease and patients exercise is limited due to angina
contraindications-chronic stable angina with limited perfusion defects or limited wall motion abnormality |
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If coronary angiogram is contraindicated, what should the managment of angina be?
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Medical management
Antianginal drugs are recommended as needed. |
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What does troponin elevation suggest?
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myocardial damage; this is Non ST Elevation MI or NSTEMI (damage has already occured)
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What is the hallmark sign of T wave inversion?
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susggest significant ischemia
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What are the causes of unstable angina/non-ST elevated MI?
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Thrombus or thromboembolism, usually arising on disrupted or eroded plaque
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What on an EKG is the biggest risk for death or MI within 30 days?
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ST depression
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If patient presents with ACS symptoms, and EKG shows ST elevation, what is the next step?
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use MI guidelines
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If patient presents with ACS symptoms, and EKG doesn't show ST elevation, but does show ST or T wave changes, what is next step?
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admit and use acute ischemia pathway
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If patient presents with ACS symptoms, but EKG and biomarkers are normal, what is the next step?
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Observe and repeat same tests in 4-8 hours; if tests are positive, admit and use acute ischemia pathway
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If patient presents with ACS symptoms, but EKG and biomarkers are normal initally and in follow up, what is the next step?
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Adminsister a stress test to check left ventricular function; if positive stress test, amit and use acute ischemia pathway; if stress test is negative, schedule outpatient follow up
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When does cardiac catheritization and revascularization have the most benefit?
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reducing ischemic complications in patients with positive troponin T levels and in those with ischemic ST segment abnormalities
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When is invasive strategy recommended in patients with non-STEMI ACS?
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in patients with any high risk indicators
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What long term lifestyle modifications are recommended in patients with non-STEMI ACS?
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smoking cessation
diet/exercise education medications |
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What is the mechanism of ST elevation?
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With ischemia involving the outer ventricular layer (transmural or epicardial injury), the ST vector is directed outward. Overlying leads record ST elevation.
Reciprocal ST depression can appear in contralateral leads. |
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What is the ED evaluation in patients with STEMI?
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1. Airway, breathing, circulation (ABCs)
2. vital signs, general observation 3. check for jugular venous distension 4. pulmonary auscultation for rales 5. cardiac auscultations for murmurs or gallops 6. check for stroke 7. check for pulses 8. check for hypoperfusion (cool, clammy, pale, ashen) |
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What is the most important factor in treatment of STEMI?
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TIME!!
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