MP NHM CHO-2024 (Shif…: Which of the following is a cause of obstructive coronary artery disease?

MP NHM CHO-2024 (Shift-2)

Medical & Surgical Nursing

Easy

Appeared in: MP NHM CHO-2024 (Shift-2)

Explanation

Plaque buildup, the process of atherosclerosis, is the primary cause of obstructive coronary artery disease (CAD).
This process involves the accumulation of cholesterol, fats, and other substances on the artery walls, forming hard structures called plaques.
These plaques physically narrow the artery's lumen, creating a fixed stenosis (obstruction) that limits blood flow to the heart muscle.
According to pathology textbooks, an obstruction is typically considered significant or 'fixed' when it blocks more than 70-75% of the artery's cross-sectional area, directly causing obstructive CAD.

Option A: Myocardial bridging is a congenital anomaly where a segment of a coronary artery tunnels through the heart muscle. This causes intermittent, dynamic compression of the artery during systole (heart contraction), not a fixed, permanent obstruction within the vessel.
Option B: Coronary vasospasm is a sudden, temporary, and severe constriction of a coronary artery. This is a functional problem (e.g., Prinzmetal's angina) that transiently reduces blood flow, rather than a permanent structural blockage like a plaque.
Option D: Endothelial dysfunction is an early stage in the development of atherosclerosis where the inner lining of the artery loses its ability to dilate properly. While it contributes to plaque formation over time, by itself it is considered a cause of non-obstructive ischemia, often affecting the microvasculature.

Visual 1: Diagram: Progression of Atherosclerosis - A visual showing a cross-section of a coronary artery, starting from a healthy state and progressing to one with significant plaque buildup, clearly illustrating the narrowing of the lumen.
Visual 2: Illustration: Myocardial Bridging vs. Plaque - A side-by-side comparison showing the external compression of an artery in myocardial bridging versus the internal blockage from an atherosclerotic plaque to highlight the difference between dynamic and fixed obstruction.

Clinical Relevance

Nursing practice connection: Knowing Causes of Obstructive vs. Non-Obstructive Coronary Artery Disease helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Differentiating between obstructive and non-obstructive CAD is critical for determining the correct treatment. Obstructive CAD is often managed with revascularization procedures like stenting or bypass surgery, whereas non-obstructive causes require medical management targeting the underlying functional issue (e.g., calcium channel blockers for vasospasm).
A nurse must recognize that patients can present with similar symptoms (e.g., chest pain) from both causes, but the pathophysiology and treatment plan will be vastly different.
What if? A patient has classic angina symptoms, but a coronary angiogram reveals no significant blockages. The nurse should anticipate that the care team will investigate non-obstructive causes like vasospasm or microvascular dysfunction. Patient education would then focus on lifestyle changes and medications rather than preparing them for a stent or surgery.

How to Approach the Question

First, identify the key term in the question: 'obstructive'. This specifies the type of coronary artery disease.
Understand that 'obstructive' in this context refers to a fixed, physical blockage that narrows the artery, as opposed to a temporary or functional issue.
Evaluate each option based on this definition.
Recognize that plaque buildup (atherosclerosis) is the process that creates a fixed physical blockage.
Identify that myocardial bridging, vasospasm, and endothelial dysfunction all cause ischemia through dynamic or functional mechanisms, not a fixed obstruction.
Conclude that plaque buildup is the only option that fits the definition of an obstructive cause.

Concept Tested & Keywords

Concept Tested: Causes of Obstructive vs. Non-Obstructive Coronary Artery Disease
Stem keywords: obstructive coronary artery disease, cause
Lead-in keywords: Which
Negative lead-in flag: false