Which of the following treatments is most appropriate for hypotension in a patient with aortic stenosis?

In managing hypotension in a patient with aortic stenosis, using phenylephrine is appropriate due to its characteristics as a selective alpha-1 adrenoceptor agonist. This medication primarily causes vasoconstriction, which helps to increase systemic vascular resistance and, consequently, blood pressure. In patients with aortic stenosis, where the left ventricle is already under significant strain due to the outflow obstruction, maintaining adequate afterload is crucial. Phenylephrine supports this by increasing vascular resistance without significantly increasing heart rate, which is beneficial because tachycardia can lead to further compromised cardiac output in these patients.

In contrast, other treatments are less suitable for this scenario. Vasodilator therapy would decrease systemic vascular resistance and could further worsen hypotension, making it inappropriate for a patient experiencing low blood pressure due to aortic stenosis. Spinal or epidural anesthesia may also lead to hypotension by causing vasodilation and reducing venous return, which is not advisable in such patients. Increased fluid administration, while sometimes beneficial in general hypotensive scenarios, may not be effective in the presence of aortic stenosis, where the heart's ability to handle increased preload is compromised. Therefore, phenylephrine stands out as the most appropriate