Chapter 7

• Angina pectoris.
• Dyspnea (left ventricular heart failure).
• Effort syncope.
• Systolic ejection murmur radiating to the carotid arteries.
• Carotid upstroke delayed in reaching its peak and reduced in amplitude (parvus et tardus).
• Echocardiography shows thickened, immobile aortic valve leaflets.
• Doppler echocardiography quantifies increased transvalvular pressure gradient and reduced valve area.

Aortic stenosis is the narrowing of the aortic valve orifice, caused by failure of the valve leaflets to open normally. This reduction in orifice area produces an energy loss as laminar flow is converted to a less efficient turbulent flow, in turn increasing the pressure work that the left ventricle must perform in order to drive blood past the narrowed valve. The concentric left ventricular hypertrophy that develops as a major compensatory mechanism helps the left ventricle cope with the increased pressure work it must perform. These factors—turbulence, energy loss, and hypertrophy—constitute the pathophysiologic underpinnings for the patient’s symptoms. The disease is confirmed through history and physical examination, Doppler echocardiography, and cardiac catheterization.

### Bicuspid Aortic Valve

This is the most common congenital cardiac abnormality, occurring in approximately 2% of the population. It is believed that the bicuspid valve has hemodynamic disadvantages compared with the normal tricuspid valve, leading to valvular degeneration by mechanisms that are still not fully understood. At least mild aortic stenosis develops in approximately 50% of all patients with bicuspid aortic valves, usually by age 50. Bicuspid aortic valve is associated with aortic dilatation and an increased risk of dissection and rupture, independent of any associated valve disease.

### Tricuspid Aortic Valve Degeneration

Many patients born with normal tricuspid aortic valves eventually develop senile degeneration of the valve leaflets and leaflet calcification, thus producing valvular stenosis. Although hypercholesterolemia and diabetes have been defined as risk factors for this degeneration, these conditions account for only a small percentage of all cases. The mechanisms by which some valves degenerate and become stenotic while others remain relatively normal are unknown but are probably related to genetic polymorphisms.

### Congenital Aortic Stenosis

Fusion of the valve leaflets before birth produces congenital aortic stenosis that is occasionally detected for the first time in adulthood. In many respects, however, congenital aortic stenosis appears to differ from acquired adult aortic stenosis. The hypertrophy in congenital aortic stenosis is more exuberant, yet heart failure symptoms. The first clinical manifestation of the disease can be sudden death without the development of premonitory symptoms in about 15% of patients.

### Rheumatic Fever

Rheumatic fever still occasionally causes aortic stenosis in the United States, although this cause is more common in developing nations. Rheumatic heart disease almost never attacks the aortic valve in isolation, usually also affecting the mitral valve to some degree. A patient with aortic stenosis and a perfectly normal mitral valve is considered to have degenerative rather than rheumatic aortic stenosis.

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