The pressure-volume loop shown above compares a control heart with a heart affected by mitral stenosis. Which of the following changes is characteristic of the mitral stenosis loop compared to the control loop?

Explanation

## Image Findings * The image displays two Left Ventricular Pressure-Volume (PV) loops: a 'Control Loop' (gray) and a 'Mitral Stenosis' loop (red). * The 'Mitral Stenosis' loop is shifted to the left compared to the 'Control Loop', indicating lower ventricular volumes. * The 'Mitral Stenosis' loop is narrower horizontally than the 'Control Loop'. * The peak Left Ventricular Pressure (LVP) in the mitral stenosis loop is similar to or slightly lower than the control loop. ## Diagnosis **Key Point:** The PV loop for mitral stenosis demonstrates a **reduced Left Ventricular End-Diastolic Volume (LVEDV)** and **reduced Stroke Volume (SV)**. Mitral stenosis is a valvular heart disease characterized by obstruction to blood flow from the left atrium to the left ventricle during diastole. This obstruction leads to incomplete filling of the left ventricle. As a result, the **Left Ventricular End-Diastolic Volume (LVEDV)** is significantly reduced, which is evident as the leftward shift and narrower appearance of the PV loop in the image. Since stroke volume (SV) is the difference between LVEDV and Left Ventricular End-Systolic Volume (LVESV), a reduced LVEDV directly leads to a **reduced Stroke Volume (SV)**, assuming LVESV remains similar or slightly reduced. ## Differential Diagnosis | Feature | Mitral Stenosis | Aortic Stenosis | Mitral Regurgitation | | :---------------------- | :-------------------------------------------- | :-------------------------------------------- | :------------------------------------------------ | | **LVEDV** | **Reduced** (due to impaired filling) | Normal or increased (compensatory) | Increased (due to regurgitant volume) | | **LVESV** | Normal or slightly reduced | Increased (due to increased afterload) | Reduced (due to forward flow + regurgitant flow) | | **Stroke Volume (SV)** | **Reduced** (narrower loop) | Reduced (due to increased afterload) | Increased total SV (forward + regurgitant), but reduced effective SV | | **LVP (Systolic)** | Normal or slightly reduced | **Increased** (due to increased afterload) | Normal or slightly reduced | | **Loop Shape** | Narrower, shifted left | Taller, narrower, shifted right (increased ESV) | Wider, shifted right (increased EDV) | ## Clinical Relevance **Clinical Pearl:** Patients with mitral stenosis often present with dyspnea on exertion, orthopnea, and paroxysmal nocturnal dyspnea due to elevated left atrial and pulmonary venous pressures. The reduced cardiac output contributes to fatigue and exercise intolerance. ## High-Yield for NEET PG **High-Yield:** The most characteristic finding on a PV loop for mitral stenosis is a **reduced LVEDV** and consequently **reduced stroke volume**, reflecting impaired diastolic filling. **Key Point:** The area enclosed by the PV loop represents the **stroke work** of the left ventricle. In mitral stenosis, both stroke volume and stroke work are reduced. ## Common Traps **Warning:** Do not confuse the PV loop changes of mitral stenosis with those of aortic stenosis (increased LVP, increased LVESV, often reduced SV) or mitral regurgitation (increased LVEDV, increased total SV, reduced effective SV). Each valvular lesion has a distinct PV loop signature. ## Reference [cite:Harrison's Principles of Internal Medicine, Ch 271]