A 52-year-old woman from Mumbai with a history of rheumatic heart disease presents with chest pain and syncope on exertion. On examination, she has a harsh systolic murmur best heard at the right upper sternal border, a slow rising carotid pulse, and a narrow pulse pressure. Echocardiography shows severe aortic stenosis with a valve area of 0.6 cm². Regarding the hemodynamics, clinical features, and management of aortic stenosis, all of the following are true EXCEPT:

Explanation

## Hemodynamics and Pathophysiology of Aortic Stenosis ### The Pulse Pressure Mechanism **Key Point:** The narrowed pulse pressure (reduced difference between systolic and diastolic BP) in aortic stenosis is primarily due to **reduced stroke volume and decreased aortic compliance**, NOT increased peripheral vascular resistance. **Clinical Pearl:** The stenotic valve acts as a fixed obstruction, reducing the volume of blood ejected per beat. The left ventricle generates high systolic pressure to overcome the stenosis, but diastolic pressure remains relatively normal because the stenotic valve restricts diastolic runoff. This creates the characteristic narrow pulse pressure. **High-Yield:** Narrow pulse pressure = reduced (systolic − diastolic) = reduced stroke volume. This is the fundamental hemodynamic derangement in aortic stenosis. ### Why the Other Options Are Correct | Feature | Explanation | |---------|-------------| | **Exertional syncope** | During exercise, the heart cannot increase cardiac output adequately (fixed stenotic valve limits flow), so systemic BP fails to rise. Cerebral perfusion drops, causing syncope. This is a cardinal symptom of severe AS. | | **LV hypertrophy** | The LV thickens to maintain wall stress (Laplace's law: wall stress ∝ pressure/wall thickness). Initially adaptive, but over time leads to impaired relaxation and diastolic dysfunction. | | **AVR indication** | Symptomatic severe AS (any symptom: angina, syncope, dyspnea) is an absolute indication for aortic valve replacement, regardless of LVEF. Even if LVEF is preserved, symptoms indicate critical stenosis. | ### Why Option 0 Is Wrong The statement incorrectly attributes narrow pulse pressure to increased peripheral vascular resistance. In fact, the narrowed pulse pressure results from: 1. **Reduced stroke volume** — the stenotic valve limits forward flow 2. **Reduced aortic compliance** — the aorta is stiffer and less distensible Peripheral vascular resistance may actually be normal or even reduced as a compensatory mechanism. [cite:Harrison 21e Ch 297]