Stress And Contrast Echo Flashcards
Define angiography vs angioplasty:
Angiography: Dye injected into the artery to display luminal contour of the artery
Angioplasty: Balloon and stent to treat a blocked artery
What is the stage of sensitivity for stress ECG?
Initial stage of detection of exercise induced ECG changes
What is the statistical sensitivity and specificity for stress ECG?
Se = 51-63% Sp = 62-74%
What is the stage of sensitivity for stress echo?
Able to identify segmental wall motion abnormalities due to exercise-induced ischemia
What is the statistical sensitivity and specificity for stress echo?
Se = 74-97% Sp = 64-100%
What is the stage of sensitivity for nuclear stress?
Detects perfusion changes during exercise using radioactive dye
What is the statistical sensitivity and specificity for nuclear stress?
Se = 61-94% Sp = 81%
What is the stress ECG test also known as?
ETT (Exercise tolerance test)
What is the principle of an ETT?
Physical stress induces ischemia of the myocardium
Target HR is what percent of the max HR with a stress ECG?
85-90%
How is max HR calculated with a stress ECG test?
Max HR = 220-age
How is target HR calculated with a stress ECG test?
Target HR = 220 - age X 0.85
As the duration of ischemia persists, a chain of events then follow. List them:
- Myocardial O2 supply/demand imbalance
- Perfusion abnormalities
- Diastolic Dysfunction
- Systolic Dysfunction
- Increase LV filling pressures
- ECG changes
- Angina
Where can echo detect ischemia in the chain of events leading to angina?
Middle of the chain
Describe stage 1 of the Bruce Protocol:
Speed: 1.5 mph
Grade: 10%
Cumulative time: 3 mins
METs: 5
What does METs stand for?
Metabolic equivalent of task
Describe stage 2 of the Bruce Protocol:
Speed: 2.7 mph
Grade: 12%
Cumulative time: 6 mins
METs: 7
Describe stage 3 of the Bruce Protocol:
Speed: 3.4 mph
Grade: 14%
Cumulative time: 9 mins
METs: 10
Describe stage 4 of the Bruce Protocol:
Speed: 4.2 mph
Grade: 16%
Cumulative time: 12 mins
METs: 13
Describe stage 5 of the Bruce Protocol:
Speed: 5.0 mph
Grade: 18%
Cumulative time: 15 mins
METs: 15
Describe stage 6 of the Bruce Protocol:
Speed: 5.5 mph
Grade: 20%
Cumulative time: 18 mins
METs: 18
Describe stage 7 of the Bruce Protocol:
Speed: 6.0 mph
Grade: 22%
Cumulative time: 21 mins
METs: 20
Assessment of workload is measured by what?
Metabolic equivalents (METs)
Workload is a reflection of what?
Oxygen consumption
1 MET is equivalent to what?
3.5 ml oxygen/kg per minute (oxygen of an average individual at rest)
How many METs are required to carry out the activities of daily living?
5 METs
Describe the normal electrocardiographic changes during exercise:
- P wave increases in height
- R wave decreases in height
- J point becomes depressed
- ST segment becomes sharply upsloping
- QT interval shortens
- T wave decreases in height
What are findings suggesting high probability of CAD?
- Horizontal ST segment depression of >2 mm
- Downsloping ST segment depression
- Early positive responsive within six minutes
- Persistence of ST depression for more than six minutes into recovery
- ST segment depression in five or more leads
- Exertional hypotension
What is the primary use of stress echo?
Assessment of cardiac perfusion
In stress echo, increased cardiac workload is used to unmask what?
Perfusion defects (ischemia) that may be silent at rest
Maximum workload equation:
Maximum workload = max HR X max BP
List the acquisition of a baseline set of images for stress echo:
- PLAX
- PSAX (pap)
- Apical 4
- Apical 2
What are some technical points for stress echo?
- Optimal endocardial definition needed
- Acquire images quickly after exercise (workload declines rapidly)
- Use 3D/4D
How long do you have to obtain all 4 cine clips post treadmill test?
- Long axis: PLAX/A3C
- PSAX (mid)
- A4C
- A2C
What is the equation for wall motion score index?
WMSI = sum of all wall scores / # of segments visualized
What is the score and definition of normal/hyperkinesis wall motion?
Score: 1
Systolic wall thickening: >40%
What is the score and definition of hypokinetic wall motion?
Score: 2
Systolic wall thickening: 10-40%
What is the score and definition of akinetic wall motion?
Score: 3
Systolic wall thickening: <10%
What is the score and definition of dyskinetic wall motion?
Score: 4
Definition: Wall thinning and moving outward in systole
What is dobutamine?
A synthetic catecholamine
Who is dobutamine used for with stress echo?
Patients who cannot exercise or for viability tissue studies
What are the effects of dobutamine?
Increases HR and inotropy. Increases O2 demand which can trigger ischemia
What data is recorded in a dobutamine stress test protocol?
HR, BP, symptoms (CP, SOB, syncope), ECG, echo images
Which does dobutamine affect more, contractility or HR?
Contractility
Why may atropine be given to augment the HR to reach target?
If peripheral vasodilation occurs or if patient was on beta blockers
What are endpoints for stopping a dobutamine stress echo?
- Reaching the maximum protocol dose
- Patient discomfort
- A definite wall motion abnormality involving two or more adjacent segments
- ST segment elevation on ECG
- Reaching 85% of max predicted heart rate for age
- A systolic BP >200 mmHg or a diastolic BP >120 mmHg
- Significant ventricular arrhythmias
Contrast echo improves endocardial border delineation to assess what 4 things:
- Wall motion
- Thrombus
- Aneurysms
- TDS patients
Which contrast is injected for the right heart?
Agitated saline
Which contrast is injected for the left heart?
Difinity contrast
What should you look for with agitated saline?
ASD, PFO, rt to lt shunts
What does a tissue viability study detect?
Stunned or hibernating myocardium
Describe a stunned myocardium at rest, and with low and high doses of dobutamine:
At rest: impaired wall motion
Low dose: increases wall thickening
High dose: further increase in wall thickening
Myocardium may come back to near normal function after what?
Reperfusion intervention
Describe a hibernating myocardium at rest, and with low and high doses of dobutamine:
At rest: impaired wall motion
Low dose: increased wall thickening
High dose: reduction in wall thickening
Describe infarcted myocardium at rest, and with low and high dose of dobutamine:
At rest: impaired wall motion
Low dose: no change in wall thickening
High dose: no change in wall thickening
What does MIBI stand for?
Methoxy IsoButyl Isonitrile
What is a MIBI?
Nuclear scan where radioactive tracers display where they end up in the heart
What can a cardiac MRI reliably image?
Coronary arteries