Stress Testing Flashcards
What is a stress test?
A provocative measure to disclose or provoke disease.
During a stress test, what is being stressed?
The cardiovascular system. Usually cardiac perfusion, via exercise or drugs.
Name five methods for stressing: (7 examples given)
1) Harvard step test 2) treadmill 3) bicycle ergometer 4) arm ergometer 5) toe raises 6) walk in hall 7) drugs
Name several indications for stress testing: (6 examples given)
*Suspected CAD *detect arrhythmias *evaluate cardiac function *evaluate therapy *LE arterial disease *sports medicine
Which is the most common method of stress testing?
Treadmill, using Bruce protocol
What is MVO2?
Myocardial oxygen demand
Define ischemia:
Insufficient supply of oxygen to tissue.
Lack of blood flow to tissue.
In the cardiac cycle, O2 demand is created during _____, and satisfied during ______.
Systole
Diastole
What does CAD stand for?
Coronary Artery Disease
What causes CAD?
Obstruction of coronary arteries, usually by plaque or clot.
What is the usual mechanism of M.I.?
Rupture of plaque, thrombosis, and sudden occlusion of artery.
How severe must plaque be to cause M.I.?
Not necessarily hemodynamically significant.
What implication does that have for the utility of stress testing?
It will miss some lesions that can still cause M.I.
May not show up on stress test.
How is cardiac ischemia detected during stress testing?
Changes in ECG, specifically in the ST segment.
What are the ST criteria for stress-induced ischemia?
ST depression 2 mm, ST elevation 1 mm, ST slope (maybe), T wave inversion
What is the J point?
End point of QRS complex; marks beginning of ST segment.
What are three forms of ST sloping?
Downslope. Upslope. Horizontal.
Which form of ST sloping is a poor indicator of ischemia?
Upslope
What is angina?
Chest pain (and/or neck-jaw, and/or left arm), usually with exertion.
What is stable vs unstable angina?
Stable is predictable with given activity level.
Unstable can occur with rest. Bad sign.
Is chest pain the only symptom of CAD?
No; other symptoms (pressure, SOB, fatigue, etc.) possible, especially in female patients.
What test might be combined with treadmill to disclose ischemia?
Thallium (nuclear med) perfusion test.
Define sensitivity:
Ability to call positive when it’s truly positive
Define specificity:
Ability to call negative when it’s truly negative.
What is the overall accuracy (positive and negative) of treadmill testing?
Roughly 75%
True or false: Since treadmill testing is only about 75% accurate, it isn’t very useful.
False, it is still useful. Especially when positive.
Name a couple of causes of false positive or false negative with treadmill testing:
BBB, MV prolapse, diuretics, previous MI
What is the maximum heart rate?
How is it calculated?
Predicted max rate heart can achieve.
220-age.
What is the target heart rate?
How is it calculated?
Rate to shoot for in a test.
Usually 85% of max rate.
What test data are/might be collected during a stress test?
Duration, heart rate, BP, ST changes, any arrhythmias, possibly oxygen consumption, any anginal pain or claudication, any dyspnea
Why is electrode prep important (more than for resting ECG)?
All that moving creates ECG noise.
What should you monitor carefully during the test?
Patient condition
What visual cues might be important to note?
Breathing, sweating, skin color, ability to talk and interact, facial expression
What two aspects of the exercise are changed during the Bruce protocol?
Speed and grade
How long are the stages of the Bruce protocol?
3 minutes
How much increase in speed and grade with each stage?
About 0.8 mph per stage, 2% grade per stage.
What are good reasons to stop the stress test?
Positive ECG changes; Reached target HR; Pain, angina or otherwise (like claudication); SOB; Finished all stages! Arrhythmia; Drop in BP; Drop in O2 sat; Patient desires to quit
What arrhythmias call for stopping the stress test?
V tach; PVC’s (frequent); Paired PVC’s; Heart block develops (2nd or 3rd degree)
What is significant about the recovery period?
Must watch patient carefully; can be a dangerous period if there’s disease.
What condition usually calls for stress testing in the vascular lab?
Claudication; LE PAD
What forms can the stress for stress testing take?
Treadmill; toe-raises; walk hallway
What causes a drop in ankle pressure compared to resting?
Exercise causes vasodilatation, increased flow through stenosis (and through collaterals), increased loss of energy (ex: pressure)
How much drop is mild?
How much drop is severe?
20% is mild
50% is severe
What ABI suggests the stress test is unlikely to be useful?
Less than around 0.40
Arterioles are likely already maximally dilated.
How do you calculate the Mean Arterial Pressure (MAP)?
MAP = 1/3 pulse pressure + diastolic pressure
