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Which coronary artery is most often involved in myocardial infarction due to its supply to a large portion of the heart muscle?

A.

Circumflex artery

B.

Right coronary artery

C.

Posterior descending artery

D.

Left anterior descending artery

Answer and Explanation

The Correct Answer is D

A. Circumflex artery:
 The circumflex artery primarily supplies the lateral and posterior walls of the left ventricle and the left atrium. While occlusion can cause MI, it is less commonly involved than the LAD because it supplies a smaller portion of the myocardium in most individuals.

B. Right coronary artery:
 The RCA supplies the right atrium, right ventricle, inferior left ventricle, and parts of the conduction system. While it can cause inferior MI when occluded, it is not the artery most frequently associated with large anterior infarctions.

C. Posterior descending artery:
 The posterior descending artery (PDA) is a branch of either the RCA or circumflex depending on dominance. It supplies the inferior septum, but infarctions here are usually smaller than those caused by LAD occlusion.

D. Left anterior descending artery:
 The LAD artery supplies the anterior wall of the left ventricle and the interventricular septum, which are critical for left ventricular contraction. Occlusion of the LAD is often called a “widowmaker MI” because it affects a large portion of the myocardium and is associated with high mortality.

 


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Related Questions

Correct Answer is A

Explanation

A. Ventricular systole:
Semilunar valves (aortic and pulmonic) open when ventricular pressure exceeds arterial pressure during systole, allowing blood to be ejected into the aorta and pulmonary artery.

B. Isovolumetric relaxation:
During this phase, the ventricles relax and pressure falls, causing the semilunar valves to close to prevent backflow.

C. Atrial systole:
During atrial contraction, the AV valves are open to fill the ventricles; semilunar valves remain closed.

D. Ventricular diastole:
During diastole, the ventricles fill with blood, and the semilunar valves remain closed until the next systole.

Correct Answer is A

Explanation

A. Left anterior descending artery:
The LAD artery is the main supplier of the anterior wall of the left ventricle and the interventricular septum, which is crucial for coordinated ventricular contraction. Occlusion can cause a large anterior myocardial infarction and severe left ventricular dysfunction.

B. Right coronary artery:
The RCA primarily supplies the right atrium, right ventricle, and inferior wall of the left ventricle. It has a lesser role in anterior left ventricular perfusion.

C. Posterior descending artery:
The PDA supplies the inferior septum and posterior left ventricle, not the anterior wall or majority of the left ventricle.

D. Circumflex artery:
The circumflex artery supplies the lateral and posterior walls of the left ventricle. It does not supply the anterior wall or the main interventricular septum.

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