- 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.
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
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
Systemic lupus erythematosus, severe familial hypercholesterolemia, and ochronosis have occasionally been reported to cause valvular
Grotenhuis HB et al. Reduced aortic elasticity and dilatation are associated with aortic regurgitation and left
ventricular hypertrophy in nonstenotic bicuspid aortic valve patients.
J Am Coll Cardiol. 2007 Apr 17;49(15):1660–5.
O’Brien KD. Epidemiology and genetics of calcific aortic valve disease. J Investig Med. 2007 Sep;55(6):284–91.
Angina, effort syncope, and congestive heart failure are the classic symptoms in patients with acquired aortic stenosis. Angina is the
presenting symptom in approximately 35% of patients, effort
syncope in 15%, and congestive heart failure in 50%.
The onset of these symptoms heralds a dramatic increase in the mortality
rate for these patients if aortic valve replacement is not performed.
Symptoms are therefore the guidepost for intervention, and understanding
them is key to understanding and managing the disease.
Angina occurs in response to myocardial ischemia, which develops
when left ventricular oxygen demand exceeds supply. It should be
noted that although epicardial coronary artery disease may coexist
with aortic stenosis, angina frequently occurs in aortic stenosis
in the absence of coronary artery disease.
As noted earlier, concentric left ventricular hypertrophy develops as a compensatory response to the pressure overload of aortic stenosis. The load on individual myocardial fibers can best be described as
left ventricular wall stress and defined by the Laplace equation:
As left ventricular pressure increases, a parallel increase in left ventricular wall thickness (concentric hypertrophy) helps offset
the pressure overload and maintain stress in the normal range. The
left ventricular myocardium must produce stress in order to shorten;
maintaining normal stress facilitates shortening. This compensatory
mechanism is attended by negative pathophysiologic sequelae, however.
Despite normal epicardial coronary arteries, the coronary blood
flow is reduced; although the flow may be normal at rest, the reserve
needed to offset increased oxygen demands during stress or exercise is inadequate, and thus ischemia develops. The exact mechanism by
which the coronary blood flow reserve is reduced in aortic stenosis
is uncertain, but low capillary density per unit of muscle is at
least one operative factor.
Oxygen demand is best estimated clinically by the product of
heart rate and wall stress. As noted earlier, the hypertrophy initially
maintains wall stress in the normal range, and despite the pressure
overload, myocardial oxygen demand is not increased. Eventually,
however, the hypertrophy cannot keep pace with the pressure demands
of the ventricle, and wall stress increases. This increases oxygen
demand and is another factor contributing to ischemia and the symptoms
In general, syncope results from inadequate cerebral perfusion. The syncope of aortic stenosis usually occurs during exercise. One
theory for exertional syncope in aortic ...