Nitroglycerin Use in Cardiac CT Scans

Indications and Contraindications

• The American College of Cardiology recommends administering sublingual nitroglycerin immediately before coronary CT angiography to achieve coronary vasodilation and improve image quality 1
• Nitroglycerin is not routinely administered for cardiac CT performed to evaluate endocarditis or device-related infections, as these patients may be hemodynamically unstable and the medication could be hazardous 2
• Beta-blockers and nitroglycerin may be contraindicated in patients with conditions such as aortic stenosis and should be used with caution depending on clinical status and in consultation with the referring cardiologist 3

Safety Considerations

• Nitroglycerin can cause inadvertent systemic hypotension, resulting in reflex tachycardia and worsening myocardial ischemia 4
• All transdermal medication patches, including nitroglycerin, should be removed from the chest before defibrillation to prevent arcing and potential small explosions from the aluminum backing 5

Practical Algorithm

• For coronary CTA, administer sublingual nitroglycerin (0.3-0.4 mg) immediately before scanning for coronary vasodilation, and ensure the patient can tolerate nitroglycerin (no recent phosphodiesterase inhibitor use, adequate blood pressure) 1, 6, 7
• For non-coronary cardiac CT (endocarditis, device evaluation), do not routinely administer nitroglycerin, and existing patches may remain unless the patient is hemodynamically unstable 2