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IMAGE INTERPRETATION · CARDIAC IMAGING

Dobutamine Stress for Myocardial Perfusion Imaging

Myocardial perfusion scan — dobutamine stress protocol
Myocardial perfusion scan — dobutamine stress protocol

CC BY-SA 4.0 · Sincefalastrum / Wikimedia Commons · source file

Question

A patient with severe COPD requiring home oxygen cannot exercise on a treadmill. The nuclear medicine physician orders pharmacologic stress MPI. The PREFERRED stress agent in this patient with severe reactive airway disease is:

  1. ADobutamine — a positive inotrope/chronotrope that increases heart rate and MVO2 without the bronchospasm risk of adenosine-based agents
  2. BDipyridamole — same mechanism as adenosine, safe in all COPD patients
  3. CAdenosine — preferred in all patients who cannot exercise
  4. DRegadenoson — no bronchospasm risk in severe COPD
Show the answer and explanation

A. Dobutamine — a positive inotrope/chronotrope that increases heart rate and MVO2 without the bronchospasm risk of adenosine-based agents

Dobutamine is the preferred pharmacologic stress agent when vasodilators (adenosine, dipyridamole, regadenoson) are contraindicated due to severe reactive airway disease (asthma exacerbation, COPD with severe bronchospasm). Dobutamine acts as a positive inotrope and chronotrope via beta-1 stimulation, increasing heart rate and myocardial oxygen demand (like exercise), thereby revealing flow-limiting coronary stenoses. Adenosine and dipyridamole carry the risk of bronchoconstriction via A2B adenosine receptors in reactive airway disease. Regadenoson has a more selective A2A profile but still carries some bronchospasm risk in severe COPD and is relatively (not absolutely) contraindicated.

More cardiac imaging images

Myocardial perfusion imaging — comparison of SPECT and PETPET vs SPECT MPI: Absolute Myocardial Blood Flow Tc-99m PYP scan: anterior and posterior chest views with ROI circles and heart-to-lung ratio of 1.6Tc-99m PYP Heart-to-Lung Ratio for Cardiac Amyloidosis Tc-99m PYP scan: anterior and posterior chest views with ROI measurements and H/CL ratio of 1.63Tc-99m PYP Amyloid Scan Protocol Myocardial perfusion SPECT — stress (top) and rest (bottom) imagesNormal Myocardial Perfusion SPECT, Stress and Rest Nuclear medicine myocardial perfusion scan — normal studyMyocardial Perfusion Tracers: Sestamibi and Tetrofosmin Cardiac SPECT without attenuation correction (top row) vs. with attenuation correction (bottom row)Diaphragmatic Attenuation Artifact on Cardiac SPECT
← Prominent Right Ventricle on MPI: RV HypertrophyPET vs SPECT MPI: Absolute Myocardial Blood Flow →

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