What Is Aortic Stenosis?

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Aortic stenosis is a valvular heart disease caused by incomplete opening of the aortic valve. This obstruction of the outflow from the left ventricle can occur as a defect of the aortic valve itself, or be caused by an obstruction above or below the valve. This obstruction thus increases the left ventricular pressure and leads to hypertrophic cardiomyopathy.

When valvular aortic stenosis occurs in childhood it is most often congenital, as is most aortic stenosis that occurs above and below the aortic valve. When aortic stenosis occurs in old age it is usually caused by hardening of the valves. The aortic valve controls the direction of blood flow from the left ventricle to the aorta. When in good working order, the aortic valve does not impede the flow of blood between these two spaces.When the aortic valve becomes stenotic, it causes a pressure gradient between the left ventricle (LV) and the aorta.The more constricted the valve, the higher the gradient between the LV and the aorta

In individuals with Aortic Stenosis(AS), the left ventricle (LV) has to generate an increased pressure in order to overcome the increased after load caused by the stenotic aortic valve and eject blood out of the LV. The more severe the aortic stenosis, the higher the gradient is between the left ventricular systolic pressures and the aortic systolic pressures. Due to the increased pressures generated by the left ventricle, the myocardium (muscle) of the LV undergoes hypertrophy (increase in muscle mass). This is seen as thickening of the walls of the LV. The type of hypertrophy most commonly seen in AS is concentric hypertrophy, meaning that all the walls of the LV are (approximately) equally thickened.

There are two pro typical processes that can affect the aortic valve. The first one is aortic stenosis in which the valve fails to open fully, thereby obstructing blood flow out from the heart. The common causes of aortic stenosis are rheumatic fever, degenerative calcification and congenital diseases. The second, aortic insufficiency is also called aortic regurgitation, in which the aortic valve is incompetent and blood flows passively back to the heart in the wrong direction. The common causes may include, dilation of the aorta, previous rheumatic fever and infection. Aortic stenosis and Aortic insufficiency conditions frequently co-exist.

There are various tests conducted. A few of them are listed below:

Electrocardiogram (ECG): Aortic stenosis does not lead to any specific findings on the ECG. But it can lead to a number of electrocardiograph abnormalities. ECG manifestations of left ventricular hypertrophy (LVH) are common in aortic stenosis and arise as a result of the stenosis having placed a chronically high pressure load on the left ventricle.

Cardiac Catheterization: By catheterizing the heart, the pressure on both sides of the aortic valve can be measured. The pressure that is measured can thus be used as a decision maker for further treatment.Though catheterization is used to measure moderate velocity stenosis, Doppler echo is more useful for faster velocities.

Echocardiogram (Heart Ultrasound): This is a non-invasive test to evaluate the aortic valve anatomy and function. Electrocardiograph flow velocities can be used to calculate the aortic valve area.

If mild aortic stenosis remains untreated and progresses into severe aortic stenosis, the left ventricle becomes further dilated and less able to contract and expel blood into the aorta. Ultimately, congestive heart failure can result if a heart valve with aortic stenosis is not repaired or replaced through surgical treatment

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