Cardiovascular physiology, fluids, and blood management: curriculum recognition: 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 · Cardiovascular physiology, fluids, and blood management: curriculum recognition

Sample item

An anaesthetised patient with severe aortic stenosis becomes tachycardic and hypotensive, and then develops ST depression. Which pressure difference determines the driving pressure for blood flow through the left ventricular coronary vessels?

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

The answer and the reasoning

A. Aortic diastolic pressure minus left ventricular end-diastolic pressure

The left ventricle is perfused mainly in diastole, when the muscle is relaxed. Coronary perfusion pressure is therefore the aortic diastolic pressure minus the left ventricular end-diastolic pressure. Tachycardia shortens diastole and hypotension lowers the aortic diastolic pressure, so ischaemia follows.

Option by option

  • A. Aortic diastolic pressure minus left ventricular end-diastolic pressure (correct)

    Correct. Perfusion occurs in diastole against the end-diastolic pressure in the ventricle.

  • B. Aortic systolic pressure minus left ventricular end-systolic pressure

    Intramyocardial pressure in systole compresses the vessels, so little flow occurs then.

  • C. Pulmonary artery wedge pressure minus aortic diastolic pressure

    The wedge pressure reflects left atrial filling, and subtracting the aortic pressure from it is meaningless.

  • D. Mean arterial pressure minus central venous pressure

    Central venous pressure reflects the right heart and is not the downstream pressure for the left ventricle.

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.

More Anaesthesia questions

Questions about this Anaesthesia question

What is the answer to this Anaesthesia question?

The best answer is A, Aortic diastolic pressure minus left ventricular end-diastolic pressure. The left ventricle is perfused mainly in diastole, when the muscle is relaxed.

Why is "Aortic systolic pressure minus left ventricular end-systolic pressure" not the answer?

Intramyocardial pressure in systole compresses the vessels, so little flow occurs then.

Why is "Pulmonary artery wedge pressure minus aortic diastolic pressure" not the answer?

The wedge pressure reflects left atrial filling, and subtracting the aortic pressure from it is meaningless.

Why is "Mean arterial pressure minus central venous pressure" not the answer?

Central venous pressure reflects the right heart and is not the downstream pressure for the left ventricle.

What concept does this question test?

It tests Cardiovascular physiology, fluids, and blood management: curriculum recognition in Anaesthesia. Coronary perfusion pressure is therefore the aortic diastolic pressure minus the left ventricular end-diastolic pressure. Tachycardia shortens diastole and hypotension lowers the aortic diastolic pressure, so ischaemia follows.

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 Cardiovascular physiology, fluids, and blood management: curriculum recognition?

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.