What clinical finding is a contraindication to the administration of nitroglycerin?

The administration of nitroglycerin is contraindicated in the presence of confirmed right ventricular infarction due to the hemodynamic effects of the drug. When nitroglycerin is given, it causes vasodilation which can lead to decreased preload and subsequently reduce the amount of blood returning to the heart. In cases of right ventricular infarction, the right side of the heart is already compromised in its ability to pump blood effectively. Therefore, reducing preload with nitroglycerin could exacerbate hypotension and lead to further cardiac dysfunction or shock.

In contrast, while left ventricular infarction and unstable angina are serious conditions, nitroglycerin can still be used in these situations, albeit with caution. Severe hypotension could also represent a contraindication depending on the prevailing clinical scenario; thus, careful monitoring is required. However, the critical aspect with right ventricular infarction lies in the risk of worsening cardiac output, making it a specific contraindication to nitroglycerin administration.