NBE Stress Echocardiography 3 — Questions and Answers
Question 1: Which stress echocardiography protocol uses a staged infusion starting at 5 mcg/kg/min and increasing to a maximum of 40 mcg/kg/min?
- Adenosine stress protocol
- Standard dobutamine stress echocardiography (DSE) protocol (Correct answer)
- Dipyridamole stress protocol
- Exercise treadmill stress protocol
Correct answer: Standard dobutamine stress echocardiography (DSE) protocol
The standard DSE protocol begins at 5 mcg/kg/min and increases in 3-minute stages to 10, 20, 30, and 40 mcg/kg/min, with atropine added if needed.
Question 2: During stress echo, a segment that is normokinetic at rest becomes akinetic at peak stress and does NOT recover. This pattern is most consistent with:
- Hibernating myocardium
- Stunned myocardium
- Inducible ischemia without viability concern (Correct answer)
- Normal stress response
Correct answer: Inducible ischemia without viability concern
New akinesis at peak stress without recovery represents inducible ischemia in presumably non-hibernating myocardium, indicating significant coronary artery disease.
Question 3: What is the target heart rate for dobutamine stress echocardiography?
- 50% of age-predicted maximum heart rate
- 70% of age-predicted maximum heart rate
- 85% of age-predicted maximum heart rate (220 minus age) (Correct answer)
- 100% of age-predicted maximum heart rate
Correct answer: 85% of age-predicted maximum heart rate (220 minus age)
The target heart rate for DSE is 85% of the age-predicted maximum heart rate (220 minus age), consistent with standard stress testing endpoints.
Question 4: Which condition is a contraindication to dobutamine stress echocardiography?
- Mild aortic stenosis
- Stable angina
- Severe hypertrophic obstructive cardiomyopathy (HOCM) (Correct answer)
- Left bundle branch block
Correct answer: Severe hypertrophic obstructive cardiomyopathy (HOCM)
Severe HOCM is a contraindication because dobutamine increases contractility and heart rate, which can dramatically worsen outflow tract obstruction and cause hemodynamic compromise.
Question 5: In a patient undergoing pharmacological stress echo with vasodilators (adenosine or dipyridamole), what is the mechanism of detecting ischemia?
- Direct myocardial stunning from the drug
- Coronary steal phenomenon causing relative hypoperfusion in diseased territories (Correct answer)
- Direct negative chronotropic effect reducing myocardial oxygen demand
- Induction of coronary vasospasm
Correct answer: Coronary steal phenomenon causing relative hypoperfusion in diseased territories
Vasodilators cause maximal dilation in normal coronary arteries, creating a 'steal' that diverts blood away from territories supplied by stenotic vessels.
Question 6: A patient develops ST-segment elevation in leads V1-V4 during dobutamine stress echo. The most appropriate immediate action is:
- Continue the infusion and reassess at next dose level
- Administer atropine to increase heart rate
- Terminate the infusion and notify physician for urgent management (Correct answer)
- Reduce dobutamine dose to 10 mcg/kg/min and continue monitoring
Correct answer: Terminate the infusion and notify physician for urgent management
ST-segment elevation during stress testing is a serious sign of transmural ischemia or vasospasm and is an absolute indication to terminate the stress protocol immediately.
Question 7: Which echocardiographic parameter best identifies diastolic dysfunction during exercise stress echocardiography?
- Decrease in E/A ratio at peak exercise
- Increase in E/e' ratio at peak exercise above 14 (Correct answer)
- Decrease in lateral e' velocity during exercise
- Increase in LVOT velocity time integral during exercise
Correct answer: Increase in E/e' ratio at peak exercise above 14
An E/e' ratio greater than 14 at peak exercise indicates elevated left ventricular filling pressures and suggests exercise-induced diastolic dysfunction.
NBE Stress Echocardiography 3
Which stress echocardiography protocol uses a staged infusion starting at 5 mcg/kg/min and increasing to a maximum of 40 mcg/kg/min?