Local and regional anaesthesia: spinal in severe aortic stenosis: practice question

A Anaesthesia question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Anaesthesia · Local and regional anaesthesia: spinal in severe aortic stenosis

Sample item

A frail patient with severe aortic stenosis needs hip fracture repair. Why is a conventional single-shot spinal generally avoided?

AReflex vasoconstriction after the block increases afterloadBThe local anaesthetic is directly cardiotoxic to the stenosed valveCA sudden fall in vascular resistance cannot be offset by a higher cardiac outputDThe block raises intracranial pressure through the narrowed valve

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

C. A sudden fall in vascular resistance cannot be offset by a higher cardiac output

In severe aortic stenosis the output is fixed, so the abrupt vasodilatation and fall in preload and afterload from a spinal cannot be compensated and coronary perfusion drops. Slowly titrated epidural or low-dose combined techniques are preferred when regional anaesthesia is chosen.

Option by option

A. Reflex vasoconstriction after the block increases afterload
The sympathetic block lowers, not raises, resistance and afterload.
B. The local anaesthetic is directly cardiotoxic to the stenosed valve
Intrathecal doses are small and are not toxic to the valve.
C. A sudden fall in vascular resistance cannot be offset by a higher cardiac output (correct)
Correct. Output is fixed, so the sympathetic block causes profound hypotension and ischaemia.
D. The block raises intracranial pressure through the narrowed valve
Spinal block has no effect on intracranial pressure through a cardiac valve.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is C, A sudden fall in vascular resistance cannot be offset by a higher cardiac output. In severe aortic stenosis the output is fixed, so the abrupt vasodilatation and fall in preload and afterload from a spinal cannot be compensated and coronary perfusion drops.

Why is "Reflex vasoconstriction after the block increases afterload" not the answer?

The sympathetic block lowers, not raises, resistance and afterload.

Why is "The local anaesthetic is directly cardiotoxic to the stenosed valve" not the answer?

Intrathecal doses are small and are not toxic to the valve.

Why is "The block raises intracranial pressure through the narrowed valve" not the answer?

Spinal block has no effect on intracranial pressure through a cardiac valve.

What concept does this question test?

It tests Local and regional anaesthesia: spinal in severe aortic stenosis in Anaesthesia. Slowly titrated epidural or low-dose combined techniques are preferred when regional anaesthesia is chosen.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Local and regional anaesthesia: spinal in severe aortic stenosis?

Make a table of each agent, its key advantage and its main side effect. Then use the flashcards and the other Anaesthesia questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.