A 52-year-old man with a history of acute rheumatic fever presents with a systolic ejection murmur at the right upper sternal border, radiating to the carotids. He has a narrow pulse pressure and a slow-rising carotid pulse. Chest X-ray shows a normal cardiac silhouette. Which investigation is most specific for confirming the diagnosis of aortic stenosis and assessing its hemodynamic severity?

## Diagnosis and Severity Assessment of Aortic Stenosis **Key Point:** Transthoracic echocardiography with Doppler is the gold standard, most specific investigation for confirming aortic stenosis and quantifying its hemodynamic severity. ### Why Transthoracic Echocardiography with Doppler? 1. **Direct visualization of the aortic valve** — identifies: - Valve morphology (bicuspid, tricuspid, calcified) - Degree of valve opening and calcification - Left ventricular hypertrophy and function 2. **Quantifies hemodynamic severity using Doppler:** - Peak aortic jet velocity (Vmax) - Peak systolic gradient (PSG) - Mean systolic gradient (MSG) - Aortic valve area (AVA) by continuity equation 3. **Guides management decisions** — determines need for aortic valve replacement (surgical or transcatheter). ### Severity Grading of Aortic Stenosis | Parameter | Mild | Moderate | Severe | |-----------|------|----------|--------| | **Vmax (m/s)** | <3.0 | 3.0–4.0 | >4.0 | | **PSG (mmHg)** | <36 | 36–64 | >64 | | **MSG (mmHg)** | <25 | 25–40 | >40 | | **AVA (cm²)** | >1.5 | 1.0–1.5 | <1.0 | **High-Yield:** The **continuity equation** is the most accurate non-invasive method for calculating AVA: $$AVA = \frac{LVOT \text{ area} \times LVOT \text{ VTI}}{AV \text{ VTI}}$$ ### Clinical Correlation with Physical Findings **Narrow pulse pressure** and **slow-rising carotid pulse** (pulsus parvus et tardus) are classic signs of hemodynamically significant aortic stenosis, suggesting severe obstruction. Echocardiography quantifies this severity. ### Role of Other Investigations **Electrocardiography** — Shows: - Left ventricular hypertrophy (LVH) with strain pattern - Conduction abnormalities - NOT specific for aortic stenosis; non-diagnostic - Cannot assess severity or valve area **Chest X-ray** — May show: - Aortic valve calcification ("aortic knob") - LVH (cardiomegaly) - NOT specific; cannot quantify severity - Normal CXR does not exclude significant AS **Exercise stress testing** — Contraindicated in symptomatic aortic stenosis due to risk of syncope and sudden cardiac death. Used only in asymptomatic severe AS to assess for inducible symptoms. **Cardiac catheterization** — Reserved for: - Coronary angiography (before valve replacement in older patients) - Discrepancy between clinical and echo findings - Therapeutic intervention (aortic balloon valvuloplasty — rarely used) - NOT first-line for diagnosis or severity assessment **Clinical Pearl:** A patient with the classic triad of aortic stenosis (systolic ejection murmur at right upper sternal border, narrow pulse pressure, slow-rising pulse) requires echocardiography to confirm diagnosis and grade severity. This determines urgency of intervention and prevents sudden cardiac death from unrecognized severe AS.