A 42-year-old man with mitral stenosis (MVA 1.2 cm²) is compared with a patient having mitral regurgitation. Which hemodynamic parameter best distinguishes mitral stenosis from mitral regurgitation on cardiac catheterization?

Question

Accepted Answer

C. Elevated pulmonary capillary wedge pressure with a prominent 'a' wave and slow 'y' descent. ## Hemodynamic Distinctions: Mitral Stenosis vs Mitral Regurgitation

**Key Point:** The pulmonary capillary wedge pressure (PCWP) tracing pattern is the most specific hemodynamic discriminator between mitral stenosis and mitral regurgitation.

### PCWP Waveform Patterns

| Feature | Mitral Stenosis | Mitral Regurgitation |
| --- | --- | --- |
| **'a' Wave** | Prominent (forceful atrial contraction against stenotic valve) | Normal or blunted |
| **'x' Descent** | Slow (atrial relaxation delayed by stenosis) | Normal |
| **'v' Wave** | Normal (atrium fills passively during systole) | Prominent (regurgitant flow into atrium) |
| **'y' Descent** | Slow (impaired diastolic filling) | Rapid (rapid atrial emptying into LV) |
| **Mean PCWP** | Elevated | Elevated |
| **LVEDP** | Normal or low (LV protected) | Elevated (LV dilatation) |

**High-Yield:** In mitral stenosis, the characteristic PCWP pattern shows a **prominent 'a' wave with a slow 'y' descent** — the "double-hump" or "M-shaped" contour. This reflects the stenotic mitral valve preventing normal diastolic emptying of the left atrium.

**Clinical Pearl:** In mitral regurgitation, the **'v' wave is prominent** because regurgitant blood flows backward into the left atrium during systole, creating a large systolic wave. The 'y' descent is rapid because the atrium empties quickly into the dilated left ventricle.

**Mnemonic:** **MS = Slow descent** (slow 'y' descent in MS); **MR = Prominent 'v'** (regurgitant wave in MR).

### Pathophysiology

```mermaid
flowchart TD
  A[Mitral Valve Lesion]:::outcome --> B{Stenosis or Regurgitation?}:::decision
  B -->|Stenosis| C[Obstruction to LA emptying]:::outcome
  C --> D[Prominent 'a' wave]:::action
  C --> E[Slow 'y' descent]:::action
  B -->|Regurgitation| F[Systolic backflow into LA]:::outcome
  F --> G[Prominent 'v' wave]:::action
  F --> H[Rapid 'y' descent]:::action
```

![Valvular Heart Disease — Mitral Stenosis diagram](https://mmcphlazjonnzmdysowq.supabase.co/storage/v1/object/public/blog-images/explanation/12205.webp)

Answer

A. Elevated left ventricular end-diastolic pressure with rapid 'x' descent

Answer

B. Reduced cardiac output with elevated systemic vascular resistance

Answer

D. Prominent 'v' wave in the pulmonary capillary wedge pressure tracing

A 42-year-old man with mitral stenosis (MVA 1.2 cm²) is compared with a patient having mitral regurgitation. Which hemodynamic parameter best distinguishes mitral stenosis from mitral regurgitation on cardiac catheterization?

Explanation

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