Regarding the pathophysiology and clinical features of mitral stenosis, all of the following are true EXCEPT:

Question

Accepted Answer

C. The stenotic mitral valve causes increased left ventricular afterload and concentric left ventricular hypertrophy. ## Pathophysiology of Mitral Stenosis

**Key Point:** Mitral stenosis causes obstruction to left ventricular filling, NOT increased afterload on the left ventricle. The pathophysiology is fundamentally different from mitral regurgitation or aortic stenosis.

### Hemodynamic Consequences

| Feature | Mitral Stenosis | Aortic Stenosis |
| --- | --- | --- |
| **LV Afterload** | Normal or ↓ | ↑↑ (increased) |
| **LV Hypertrophy** | Concentric (from pulmonary HTN) | Concentric (from valve obstruction) |
| **LA Pressure** | ↑↑ | Normal |
| **Pulmonary Congestion** | Yes, early | Late |

**High-Yield:** Mitral stenosis causes:
1. **Decreased** left ventricular preload (obstruction to filling)
2. **Normal** left ventricular afterload (the stenosis is on the inlet, not outlet)
3. Left atrial hypertrophy and dilation (not LV hypertrophy from afterload)
4. Pulmonary venous congestion → pulmonary hypertension → right ventricular hypertrophy

### Why Option 1 is Wrong

Mitral stenosis does NOT increase left ventricular afterload. The narrowed mitral valve obstructs blood flow INTO the left ventricle, reducing preload. The left ventricle itself experiences normal or reduced afterload. Concentric LV hypertrophy in mitral stenosis, when it occurs, is secondary to pulmonary hypertension (RV hypertrophy pushing the septum), not from increased LV afterload.

### Correct Features (Options 0, 2, 3)

**Option 0 (Correct):** Left atrial enlargement is a hallmark of mitral stenosis. The enlarged, fibrillating atrium is a major source of thrombi → systemic embolism (stroke is a common complication).

**Option 2 (Correct):** Elevated LA pressure is transmitted backward through pulmonary veins → pulmonary congestion, dyspnea, orthopnea, and pulmonary edema.

**Option 3 (Correct):** Rheumatic heart disease accounts for ~80–90% of mitral stenosis cases in India and other developing nations. Post-streptococcal sequela remains the dominant etiology globally.

**Clinical Pearl:** A patient with mitral stenosis presenting with dyspnea on exertion, orthopnea, and a diastolic murmur has pulmonary congestion from backward transmission of elevated LA pressure — NOT from LV dysfunction.

[cite:Robbins 10e Ch 12]

Answer

A. Rheumatic heart disease is the most common cause of mitral stenosis in developing countries like India

Answer

B. Left atrial enlargement leads to atrial fibrillation and increased thromboembolic risk

Answer

D. Pulmonary congestion occurs due to elevated left atrial pressure transmitted backward to the pulmonary vasculature

Regarding the pathophysiology and clinical features of mitral stenosis, all of the following are true EXCEPT:

Explanation

Pathophysiology of Mitral Stenosis

Hemodynamic Consequences

Why Option 1 is Wrong

Correct Features (Options 0, 2, 3)

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Feature	Mitral Stenosis	Aortic Stenosis
LV Afterload	Normal or ↓	↑↑ (increased)
LV Hypertrophy	Concentric (from pulmonary HTN)	Concentric (from valve obstruction)
LA Pressure	↑↑	Normal
Pulmonary Congestion	Yes, early	Late