Why does aortic stenosis occur

The classic triad of symptoms of aortic stenosis occur on exertion and include dyspnea, syncope and angina. The development of aortic stenosis takes many years and is initially asymptomatic latent period. The clinical significance of a patient with aortic stenosis who exhibits symptoms must not be underemphasized, as the onset of symptoms is accompanied by a dramatic increase in mortality.

According to one large series, if aortic valve replacement is not performed, patients presenting with dyspnea have a mean life expectancy of 2 years, those with syncope about 3 years and those with angina an average of 5 years.

Angina in aortic stenosis frequently occurs in the absence of coronary artery disease. Instead, myocardial ischemia and angina develop when the oxygen demand of the severely hypertrophied left ventricle exceeds oxygen supply.

It is helpful to know the Law of LaPlace, which explains the phenomenon. Using the above equation, we can understand the pathologic process that develops over many years in patients with aortic stenosis. As LV pressure slowly increases over time due to worsening aortic stenosis, a parallel increase in LV wall thickness concentric hypertrophy occurs to maintain the LV wall stress at a constant level; as discussed, LV wall stress is an important determinant of myocardial O2 demand.

Eventually, the left ventricle LV is unable to hypertrophy any further, but the LV pressure continues to rise as the aortic stenosis worsens. This leads to a rise in LV wall stress, and thus a rise in LV myocardial oxygen demand.

When the heart rate increases in response to exertion, a significant supply vs. Syncope on exertion, or effort syncope, occurs in aortic stenosis due to a sudden decrease in cerebral perfusion with physical activity.

During exercise, the total peripheral resistance TPR decreases significantly because blood is being shunted toward working muscles. In the presence of significant aortic stenosis, the cardiac output is unable to increase enough to accommodate this decreased total peripheral resistance TPR. Hypotension occurs and cerebral perfusion is compromised, resulting in syncope.

This idea can be further reinforced by the following equation:. If the cardiac output is unable to increase due to severe aortic stenosis, and the TPR decreases during exertion, MAP will subsequently be reduced, leading to decreased cerebral perfusion and syncope.

It is important to note that another cause of syncope in patients with aortic stenosis is arrhythmias, especially atrial fibrillation and AV nodal blocks; this is described later in this section. Dyspnea on exertion is due to heart failure. Both systolic and diastolic dysfunction typically contributes to heart failure in patients with aortic stenosis.

Other classic symptoms of heart failure — orthopnea, paroxysmal nocturnal dyspnea PND and signs of right sided heart failure i.

Auscultation of the heart in patients with aortic stenosis can be very helpful in both the diagnosis and in determining the severity of disease. In mild aortic stenosis, the murmur peaks in early systole. As the disease progresses, the peak moves to later in systole; with longer time required to complete LV systole, aortic valve closure is delayed.

The intensity of the murmur typically increases as disease progresses. However, when heart failure develops and cardiac output declines, the murmur becomes softer.

Thus, the intensity of the murmur is not a good indicator of disease severity. Auscultation at the cardiac apex may reveal a murmur that sounds midsystolic or holosystolic and could mimic the murmur of mitral regurgitation. However, this is commonly the result of radiation of the aortic stenosis murmur to the apex rather than coexistent mitral regurgitation. The murmur of hypertrophic cardiomyopathy can also at times mimic the murmur of aortic stenosis.

The Valsalva maneuver decreases the aortic stenosis murmur while it increases the hypertrophic cardiomyopathy murmur. The S2 heart sound is often paradoxically split in patients with aortic stenosis, though the splitting disappears on inspiration.

The split is due to the significantly delayed closure of the aortic valve resulting from the increased time needed to complete LV systole; for more on splitting of S2, see Heart Sounds Topic Review. Enlarge As disease progresses and the aortic valve leaflets lose their mobility, the intensity of S2 decreases.

When the S2 sound is no longer audible, it can be concluded that the aortic stenosis is relatively severe. As the opening becomes smaller, it makes it harder for the heart to pump blood, which can affect your health. This condition is called aortic stenosis also called aortic valve stenosis or aorta stenosis.

Aortic stenosis is a progressive disease that affects up to 2. In most elderly adults, aortic stenosis is caused by a build-up of calcium a mineral found in your blood on the valve leaflets. Over time, this causes the leaflets to become stiff, reducing their ability to fully open and close. A normal aortic valve contains three leaflets. But sometimes people are born with an aortic valve that has one, two, or four leaflets. When defects are present, the aortic valve may leak and this can cause valve problems.

Sometimes strep throat can lead to rheumatic fever which can cause scar tissue to form within the heart. When this happens, the aortic valve may not be able to open and close as it normally should. Some people may develop inflammation and scar tissue after receiving radiation therapy.

This can make the aortic valve stiff and unable to function properly. After being diagnosed with mild aortic stenosis, and living years without symptoms, Larry's condition began to worsen.

Follow Larry's journey. Living life to the fullest is important to you. But aortic stenosis can interrupt your golden years if it goes undetected and untreated. Possible treatments may include medications , valve repair or valve replacement. Written by American Heart Association editorial staff and reviewed by science and medicine advisers. See our editorial policies and staff. Recovery from a heart condition becomes so much more manageable when you have the right kind of emotional support.

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What is aortic valve stenosis? Download our aortic stenosis fact sheet PDF Does aortic stenosis always produce symptoms?