Heart: arterial supply of the conducting system: practice question

A Anatomy 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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Anatomy · Heart: arterial supply of the conducting system

Sample item

A 65-year-old man has an acute inferior wall myocardial infarction with ST elevation in leads II, III and aVF, and then develops complete heart block. Angiography shows occlusion of the mid right coronary artery in a right-dominant circulation. Which statement best explains the conduction block?

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

The answer and the reasoning

B. In most people the artery to the atrioventricular node arises from the right coronary artery at the crux of the heart

In right-dominant hearts, which are the majority, the right coronary artery gives the posterior interventricular artery and the AV nodal artery at the crux. Occlusion proximal to this point causes ischaemia of the AV node and block, usually transient in inferior infarcts. The left anterior descending artery supplies the upper septum and bundle branches.

Option by option

  • A. The atrioventricular node is supplied by the left circumflex artery in most people, so a second lesion is present

    The circumflex supplies the AV node only in left-dominant hearts, which are the minority.

  • B. In most people the artery to the atrioventricular node arises from the right coronary artery at the crux of the heart (correct)

    Correct. The AV nodal artery arises from the right coronary artery at the crux in right-dominant hearts.

  • C. The atrioventricular node is supplied by the left anterior descending artery, which is usually occluded with the right coronary artery

    The anterior descending artery supplies the anterior septum and bundle branches, not the AV node itself.

  • D. The sinoatrial nodal artery, which always arises from the left circumflex artery, also supplies the atrioventricular node

    The sinoatrial nodal artery arises from the right coronary artery in about 60% of people and the circumflex in the rest, and the AV node has its own artery.

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 Anatomy questions

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is B, In most people the artery to the atrioventricular node arises from the right coronary artery at the crux of the heart. In right-dominant hearts, which are the majority, the right coronary artery gives the posterior interventricular artery and the AV nodal artery at the crux.

Why is "The atrioventricular node is supplied by the left circumflex artery i…" not the answer?

The circumflex supplies the AV node only in left-dominant hearts, which are the minority.

Why is "The atrioventricular node is supplied by the left anterior descending…" not the answer?

The anterior descending artery supplies the anterior septum and bundle branches, not the AV node itself.

Why is "The sinoatrial nodal artery, which always arises from the left circum…" not the answer?

The sinoatrial nodal artery arises from the right coronary artery in about 60% of people and the circumflex in the rest, and the AV node has its own artery.

What concept does this question test?

It tests Heart: arterial supply of the conducting system in Anatomy. Occlusion proximal to this point causes ischaemia of the AV node and block, usually transient in inferior infarcts. The left anterior descending artery supplies the upper septum and bundle branches.

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 Heart: arterial supply of the conducting system?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.