A 59-year-old with severe persistent asthma is referred for myocardial perfusion imaging after exertional chest tightness. He cannot reach the target heart rate on the treadmill, and the study will be a gated rest and stress SPECT. Which stress agent paired with Tc-99m sestamibi best fits this patient?
Select an answer to reveal the explanation.
Short Explanation
Dobutamine fits because it boosts your heart rate and heart muscle contraction through beta receptors, rather than activating adenosine receptors that can trigger bronchoconstriction in severe asthma. It’s like taking a different route to raise your heart rate, but you’ll still need appropriate monitoring.
Full Explanation
Dobutamine is a beta-adrenergic agonist that raises heart rate and contractility, increasing myocardial oxygen demand and perfusion. It is a pharmacologic stress alternative when exercise is inadequate and adenosine-pathway agents are unsuitable because of severe asthma. Adenosine can cause bronchospasm, and regadenoson should be used cautiously in patients with asthma or other bronchoconstrictive lung disease. Treadmill exercise is not the best choice here because the patient cannot reach the target heart rate, which can reduce the sensitivity of the study. Dobutamine stress requires close rhythm and blood-pressure monitoring because arrhythmias and blood-pressure changes can occur. Review relevant medication history and monitor the patient throughout the test.