by Y Tian

Created on: April 10, 2009

The human heart is an amazing muscle that tirelessly propels blood around the body, providing every one of the three billions cells in the human body with oxygen and nutrients as well as removing the unwanted waste products. It is an organ that is divided into four parts to allow for efficient filling and pumping of blood within each cardiac cycle. Each chamber has a valve to prevent the backflow of blood during contraction. These four valves (mitral, tricuspid, aortic and pulmonary) control the vital unidirectional blood flow around the body. Thus, whenever a valve fails to perform its functions properly, there are serious health consequences. So what is aortic valve stenosis and what are its symptoms?

From its name, it can be gathered that aortic valve stenosis is a valvular disease that affects the aortic valve, which is the valve situated between the left ventricle (responsible for pumping oxygenated blood to the cells throughout the body) and the aorta (the major artery of the human body). It opens passively during ventricle contraction to allow blood to be ejected from the heart into the aorta and closes passively during ventricle filling to ensure blood does not flow backwards from the aorta into the ventricle. The valve's passive movements do not impede the blood flow.

In aortic valve stenosis, however, the valve is abnormally narrowed and consequently, impeding the flow of blood. This creates a pressure gradient between the left ventricle and the aorta, meaning that the left ventricle has to generate a higher pressure in order to overcome the increased afterload and eject blood into the aorta. The more constricted the valve, the higher the pressure gradient and consequently and the harder the left ventricle has to pump to supply the body's needs. Over time under such pressure, the left ventricle will undergo hypertrophy to try to meet up with the demands. Whenever a ventricle undergoes hypertrophy for compensation, it does not bode well for the body in the long run.

Mild aortic valve stenosis is largely asymptomatic and a patient may even have severe aortic valve stenosis for years without symptoms (due to the compensated hypertrophied left ventricle). However, over time, the demand on the left ventricle will become too much (even for the hypertrophied state) and the patient may suffer from breathlessness (dyspnea) during light exertions as the heart cannot cope with any increased demand on oxygen. In severe cases, when the patient tries to exercise, the heart's inability to provide extra oxygen may result in the patient fainting (also known as syncope). In addition, as the left ventricle hypertrophies, it elevates the heart's own demand on oxygen as well as interferes with the coronary blood vessels. This combination will cause ischemia of the coronary arteries and cause severe chest pain (clinically referred to as angina pectoris). Exertional dyspnea, syncope and angina are the three cardinal symptoms of aortic valve stenosis.

In a physical examination, abnormal heart sounds may be detected by the doctor. This is often how aortic valve stenosis is detected when it is asymptomatic. Some of the sounds that the doctor would be looking for are an early systolic ejection sound, murmurs at the upper right sternal border and prolonged left ventricle systole.

In conclusion, aortic valve stenosis is a serious cardiac condition that is largely asymptomatic until the severe stages. As a result, it is important to regularly seek medical attention and routine physical examinations.

Reference:

Harrison, T. et al. (2005) Harrison's Principles of Internal Medicine, 16th edition. McGraw-Hill Companies, Inc.

http://en.wikipedia.org/wiki/Aortic_valve_stenos is

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