A 62-year-old woman from Delhi presents with syncope during exertion while climbing stairs 2 days ago. She reports progressive exertional dyspnea for 6 months and chest discomfort on effort. On examination, blood pressure is 155/65 mmHg with a narrow pulse pressure, pulse 72/min regular. Carotid pulse is slow-rising and diminished. A systolic ejection murmur is heard at the right upper sternal border radiating to both carotids, with a single S2. Apex beat is displaced laterally. Echocardiography shows a peak aortic valve gradient of 65 mmHg, aortic valve area 0.8 cm², and left ventricular wall thickness of 18 mm. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Severe Aortic Stenosis ### Diagnostic Criteria for Severe AS **Key Point:** Severe aortic stenosis is defined by: - Aortic valve area (AVA) <1.0 cm² (this patient: 0.8 cm²) - Peak aortic gradient ≥64 mmHg (this patient: 65 mmHg) - Mean gradient ≥40 mmHg **High-Yield:** The triad of exertional syncope, exertional dyspnea, and exertional chest pain is the classic symptomatic presentation of severe AS and indicates high mortality risk (~50% within 2 years if untreated). ### Clinical Features of Severe AS | Feature | Finding | Mechanism | |---------|---------|----------| | Pulse character | Slow-rising, diminished (pulsus parvus et tardus) | Reduced stroke volume, prolonged ejection time | | Pulse pressure | Narrow (155/65) | Decreased SV and increased peripheral resistance | | S2 | Single or paradoxically split | Delayed aortic valve closure | | Murmur | Systolic ejection, right upper sternal border → carotids | High-velocity flow across stenotic valve | | Apex beat | Laterally displaced | Eccentric LVH from chronic pressure overload | | LV wall thickness | 18 mm (normal <11 mm) | Concentric hypertrophy from sustained pressure load | **Clinical Pearl:** The slow-rising carotid pulse (pulsus parvus et tardus) is a hallmark of severe AS and reflects the prolonged ejection time and reduced stroke volume. ### Pathophysiology of Symptoms ```mermaid flowchart TD A[Aortic valve stenosis]:::outcome --> B[Increased LV afterload] B --> C[LV concentric hypertrophy] C --> D[Increased LV wall stress] D --> E[Subendocardial ischemia] E --> F[Exertional chest pain]:::outcome C --> G[Reduced LV compliance] G --> H[Elevated LVEDP] H --> I[Pulmonary congestion] I --> J[Exertional dyspnea]:::outcome E --> K[Arrhythmia risk] K --> L[Syncope on exertion]:::outcome ``` **Mnemonic:** **SAD** = Syncope, Angina, Dyspnea = Classic triad of severe AS ### Why Syncope Occurs in Severe AS 1. **Fixed obstruction:** The stenotic valve cannot dilate during exertion; stroke volume cannot increase 2. **Peripheral vasodilation:** Exercise triggers reflex systemic vasodilation, but the fixed obstruction prevents compensatory increase in cardiac output 3. **Result:** Systemic hypotension and cerebral hypoperfusion → syncope This is a medical emergency—syncope in AS indicates severe disease and high risk of sudden cardiac death. **Warning:** Exertional syncope in AS is an absolute indication for aortic valve replacement (AVR). Mortality without intervention is ~50% at 2 years. ### Echocardiographic Severity Grading | Severity | AVA (cm²) | Mean Gradient (mmHg) | Peak Gradient (mmHg) | |----------|-----------|----------------------|----------------------| | Mild | >1.5 | <25 | <36 | | Moderate | 1.0–1.5 | 25–40 | 36–64 | | Severe | <1.0 | >40 | >64 | This patient meets severe criteria on both AVA and gradient. ### Management **High-Yield:** Symptomatic severe AS requires urgent aortic valve replacement (surgical or transcatheter AVR). Medical management is temporizing only—diuretics for pulmonary edema, but vasodilators are contraindicated (risk of syncope/shock).