Aortic Stenosis: Causes, Symptoms & Treatment

CAUSE: Aortic valve stenosis arises from defective valvular architecture. The ordinary dynamic stress of blood flow across the defective valve progressively traumatizes the valve, resulting in thickening, calcification, and narrowing of the valve orifice.

1. Congenital: A congenital bicuspid valve is the cause of aortic stenosis in 50% of symptomatic patients.

2. Rheumatic endocarditis leads to commissural fusion of valve leaflets, often affecting the mitral valve as well.

3. Degenerative calcific aortic stenosis occurs in elderly patients and appears to be part of the aging process. Degenerative calcific aortic stenosis is less likely to result in symptoms.

PATHOPHYSIOLOGY

1. The obstruction to ventricular outflow that results from the stenotic valve stimulates concentric hypertrophy of the left ventricle to overcome the systolic pressure gradient and maintain cardiac output. 

2. The increased muscle mass of the ventricle leads to increased myocardial oxygen demands. The hypertrophied hyperdynamic ventricle loses its ability to compensate for hemodynamic changes and eventually fails, leading to increased atrial pressures and pulmonary congestion. 

3. The ventricle also loses its ability to increase cardiac output, leading to syncope or angina with exertion. 

CLINICAL FEATURES

1. Typically, symptoms don't appear until the valve orifice has shrunk to less than 1cm2. Patients may have been diagnosed previously or may present for the first time to the ED with dyspnea, angina, or syncope.

2. Physical examination findings: The carotid arterial pulse takes longer and has less energy. The maximum impulse point could be hyperdynamic and enlarged. Auscultation of the heart reveals a harsh systolic murmur that occurs just after the S1 and is transmitted to the carotid arteries. The S2 may diminish as the disease progresses and the contribution of the aortic component (A2) is lost.

DIFFERENTIAL DIAGNOSES 

The murmur of aortic stenosis must be differentiated from other systolic murmurs such as occur with mitral regurgitation, tricuspid regurgitation, pulmonic stenosis, and hypertrophic cardiomyopathy. Significant aortic stenosis must be differentiated from insignificant flow murmurs.

EVALUATION

1. Electrocardiography: Most patients show electrocardiographic evidence of left ventricular hypertrophy.

2. Radiography: Before the development of severe aortic stenosis, a chest radiograph is typically normal. Later on, this could show indications of CHF and an enlarged cardiac silhouette.

THERAPY: The presenting complaint directs the management of emergencies. Many of these individuals will eventually require valve replacement or repair.

DISPOSITION: Patients with syncope, cardiac chest pain, CHF, or arrhythmias usually require admission to the hospital.