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Aortic valve stenosis (AS) is a heart condition caused by the incomplete opening of the aortic valve.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. Under some circumstances, the aortic valve becomes narrower than normal, impeding the flow of blood. This is known as aortic valve stenosis, or aortic stenosis, often abbreviated as AS.
1 Pathophysiology
Simultaneous left ventricular and aortic pressure tracings in aortic stenosis
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AO = Ascending aorta; LV = Left ventricle; ECG = Electrocardiogram.
Simultaneous left ventricular and aortic pressure tracings. The left ventricle generates higher pressures than what is transmitted to the aorta. The pressure gradient, caused by aortic stenosis, is represented by the green shaded area. |
When the aortic valve becomes stenotic, it causes a pressure gradient between the left ventricle (LV) and the aorta. The more stenotic the valve, the higher the gradient between the LV and the aorta. For instance, with a mild AS, the gradient may be 20 mmHg. This means that, at peak systole, while the LV may generate a pressure of 140 mmHg, the pressure that is transmitted to the aorta will only be 120 mmHg. So, while a blood pressure cuff may measure a normal systolic blood pressure, the actual pressure generated by the LV would be considerably higher.
In individuals with AS, the left ventricle (LV) has to generate an increased pressure in order to overcome the increased afterload 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.
2 Etiology
Causes of aortic stenosis include acute rheumatic fever , bicuspid aortic valve and congenital anomalies .
3 Physical examination
It is most often diagnosed when it is asymptomatic. It is found on routine examination of the heart. A fairly loud systolic, crescendo-decrescendo murmur is heard loudest at the upper right sternal border, and radiates to the carotid arteries. The murmur increases with squatting, decreases with standing and isometric muscular contraction, which helps distinguish it from hypertrophic obstructive cardiomyopathy (HOCM). RespirationRespiration can refer to: Cellular respiration, which is the use of oxygen in the metabolism of organic molecules. Physiological respiration, which exchanges oxygen and carbon dioxide between an organism and the external environment. has no effect on the loudness of the murmur.
4 Symptoms and signs of aortic stenosis
When symptomaticIn medicine, a disease is symptomatic when it is at a stage when the patient does experience symptoms. It is generally used in counterdistinction of asymptomatic (when the disease is inapparent). See also Asymptomatic., aortic stenosis can cause syncopeSyncope ''can also mean fainting (in medicine . In linguistics, syncope is the deletion of phonemes from a word, or from a phrase treated as a unit; compare elision. Syncope gives rise to many of the silent letters in English spelling. The traditional spe, anginaAngina pectoris (Latin for "pain of the chest") is the result of a lack of oxygen supply to the heart muscle, due to a reduced blood flow around the heart's blood vessels. This lack of oxygen to the heart is known as myocardial ischemia. Angina pectoris i and congestive heart failureCongestive heart failure CHF (also called heart failure is the inability of the heart to pump blood effectively to the body, or requiring elevated filling pressures in order to pump effectively. The term heart failure is frequently misused, especially whe. More symptoms indicate a worse prognosis. Treatment requires replacement of the diseased valve with either a porcine aortic valve or a cadaveric aortic valve , or an prosthetic aortic valve .
