CARDIAC STRESS TESTS-STRESS

SUMMARY

1. Exercise: must achieve/exceed 85% of age-predicted maximum HR. Not used in patients with LBBB or pacemakers as it can cause false-positive ventricular perfusion defects.

2. Dobutamine: inotrope & chronotrope. Can be used in patients with contraindications to exercise, vasodilators (such as bronchospasm), LBBB (not dobutamine MPI).

3. Vasodilatiors: adenosine, dypridamol. Work by dilating and increasing blood flow in normal cardiac vessels while doing little to change the flow in stenotic vessels.

4. The dilated normal vessels steal flow from the stenotic vessels, causing perfusion defects in scans (and ST segment changes in ECGs).

5. Vasodilators are not used in patients with history of bronchospasm.

Reference(s)

Wilkinson, I., Furmedge, D. and Sinharay, R. (2017). Oxford handbook of clinical medicine. Oxford: Oxford University Press. Get it on Amazon.
Feather, A., Randall, D. and Waterhouse, M. (2020). Kumar And Clark’s Clinical Medicine. 10th ed. S.L.: Elsevier Health Sciences. Get it on Amazon.
Hannaman, R. A., Bullock, L., Hatchell, C. A., & Yoffe, M. (2016). Internal medicine review core curriculum, 2017-2018. CO Springs, CO: MedStudy.
Therapeutic Guidelines. Melbourne: Therapeutic Guidelines Limited. https://www.tg.org.au [Accessed 2021].