Cardiac Stress Testing Flashcards
Indications for cardiac stress testing include:
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- Establish a diagnosis of CAD
- Assessment of prognosis and functional capacity (stable angina or post MI)
- Assess response to therapy
- Evaluate pre-operative cardiac risk
- Evaluate asymptomatic individuals for CAD (pilots, police, firefighters, middle aged persons wanting to start a vigorous exercise program)
- Evaluate for exercise-induced arrhythmias
What possible CAD patients are indicated for stress testing? 2
- Symptomatic
2. Asymptomatic with abnormal EKG
What kind of therapy would we want to assess? 2
- Medications
2. Revascularization
Contraindications to stress testing
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- Acute MI
- Unstable angina
- Acute pericarditis
- Acute systemic illness
- Severe aortic stenosis
- CHF exacerbation
- Severe hypertension
- Uncontrolled arrhythmias
Exercise EKG:
Instruments to use?
Often combined with what? 3
WHo should this be used in? 2
- Treadmill or bicycle ergometer
- Often combined with imaging studies
- Nuclear,
- echocardiography or
- MRI - In low risk patients without baseline ST segment abnormalities or
- when anatomic localization is not necessary exercise EKG is the recommended initial procedure
What HR do we want to get them at for exercise EKG?
Whats the most common protocol for this?
What is age predicted HR?
a minimum of 85% of the maximum age predicted heart rate
Most common protocol is the Bruce Protocol increasing the speed and incline every 3 minutes
220-age
What is monitored throughout the exercise EKG?
3
- EKG is monitored continuously during exercise
- BP response is noted in each stage of exercise (if blood pressure goes down in exercise it is a measure of severe ischemia)
- Symptoms are noted
Information obtained from EXERCISE:
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- Exercise duration and tolerance
- Reproducibility of symptoms with activity
- Heart rate response to exercise
- Blood pressure response to exercise
- Detection of stress induced arrhythmias
- Assess the effectiveness of antianginal medications
- Prognosis
Exercise EKG interpretation
What is the criteria for a positive test?
2
Using this criteria _____% of pts with significant CAD will have a positive test
But _____% of those without significant disease will also have a positive test
Criteria for a positive test is
- 1mm horizontal or
- downsloping ST segment depression measured 80 ms after the J point
60-80
10-30
Exercise EKG interpretation – High risk for significant ischemia
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- BP drop during exercise
- > 2mm ST depression
- ST depression that is downsloping
- ST depression or symptoms at low work loads less than 6 min or HR less than 70% of maximum age predicted HR
- ST depression that does not resolve quickly in the recovery phase
Risks of exercise testing
3
- 1 MI or death per 1000 patients
- Stress induced arrhythmia
- Adverse reaction to pharmacologic stress agent
The mean sensitivity improves up to about 85% with ______?
imaging.
What are the kinds of stress imaging?
- Cardiac nuclear perfusion imaging (myocardial perfusion scintigraphy)
- Stress echo
What are the kinds of stresses we can do to do the stress imaging tests? 2
Regular exercise stress
Pharmacologic stress
What are the drugs that we use for pharmalogical stress?
2
- Dobutamine (positive inotropic and chronotropic agent) used for both tests.
- Adenosine or persantine (potent vasodilators)- wont dilate because its fibrous. Can only be used for CNP