Aortic Stenosis

Essentials of Diagnosis

• In adults, usually asymptomatic until middle or old age.
  
• Delayed and diminished carotid pulses.
  
• Soft, absent, or paradoxically split S₂.
  
• Harsh systolic murmur, sometimes with thrill along left sternal border, often radiating to the neck; may be louder at apex in older patients.
  
• ECG usually shows left ventricular hypertrophy; calcified valve on x-ray or fluoroscopy; echo-Doppler is diagnostic in most cases.
  

General Considerations
Aortic valvular stenosis may follow rheumatic fever but is more commonly caused by progressive valvular calcification. This may occur in younger patients with a congenitally bicuspid valve or in elderly individuals with normal three-cusp valves. In the latter group, the aortic valve becomes sclerotic and, with further calcification, stenotic.

Approximately 25% of patients over age 65 and 35% of those over age 70 have echocardiographic evidence of sclerosis, which appears to be related to atherosclerotic vascular disease and is associated with a higher rate of vascular events. About 10-20% of these will progress to hemodynamically significant aortic stenosis over a period of 10-15 years. Thus, aortic stenosis has become the most common surgical valve lesion in developed countries. Degenerative valve disease is three to four times more frequent in men than in women and is more common in smokers and hypertensives. Valvular stenosis must be distinguished from supravalvular obstruction and from outflow obstruction of the left ventricular infundibulum, both relatively rare.

Clinical Findings

A. Symptoms and Signs
Slightly narrowed, thickened, or roughened valves (aortic sclerosis) or aortic dilation may produce the typical murmur and thrill without causing significant hemodynamic effects. In mild or moderate cases, the characteristic signs are a systolic ejection murmur at the aortic area transmitted to the neck and apex; in severe cases, a palpable left ventricular heave or thrill, a weak to absent aortic second sound, or reversed splitting of the second sound are present (see Table 10-1). When the valve area is less than 0.8-1 cm₂ (normal, 3-4 cm₂), ventricular systole becomes prolonged and the typical carotid pulse pattern of delayed upstroke and low amplitude is present, but this may be an unreliable finding in older patients with extensive arteriosclerotic vascular disease. Left ventricular hypertrophy increases progressively, with resulting elevations in ventricular end-diastolic pressure. Cardiac output is maintained until the stenosis is severe (with a valve area < 0.8 cm). Patients may present with left ventricular failure, angina pectoris, or syncope.