In STEMI, a complete occlusion of an epicardial artery results in what for blood flow beyond the blockage?

In STEMI, a complete occlusion of an epicardial artery results in what for blood flow beyond the blockage?

• A. Normal flow past the occlusion
• B. No blood flow beyond the occlusion
• C. Increased flow beyond the occlusion
• D. Flow only during systole

Answer: (B)

When a coronary artery is completely blocked, the blood cannot move past the blockage to the downstream tissue. The myocardium fed by that artery loses its perfusion, so there is essentially no forward flow beyond the occlusion. Some collateral vessels from other arteries may provide limited alternate blood supply, but this flow does not come from the blocked artery itself. The other ideas—normal flow past the blockage, increased flow beyond the blockage, or flow only during systole—don’t fit because a complete occlusion stops forward perfusion to the downstream myocardium, leading to ischemia and potential infarction if not reperfused.

When a coronary artery is completely blocked, the blood cannot move past the blockage to the downstream tissue. The myocardium fed by that artery loses its perfusion, so there is essentially no forward flow beyond the occlusion. Some collateral vessels from other arteries may provide limited alternate blood supply, but this flow does not come from the blocked artery itself. The other ideas—normal flow past the blockage, increased flow beyond the blockage, or flow only during systole—don’t fit because a complete occlusion stops forward perfusion to the downstream myocardium, leading to ischemia and potential infarction if not reperfused.