Aortic Stenosis (AS) is a disease of the aortic valve that obstructs the outflow of blood from the heart to the rest of the body. It's usually diagnosed by a combination of history, including symptoms of chest pain and dizziness, as well as physical exam findings such as a new heart murmur. When suspected, AS is best diagnosed by an echocardiogram--a non-invasive ultrasound of the heart that can assess the severity of the stenosis, or narrowing, of the valve with regard to the strain it puts on the heart. These measurements via an echocardiogram also determine if and when a valve replacement may be beneficial.
Dizziness
In AS, blood flow out of the heart is diminished because of the narrowing of the valve. This decreases the amount of blood flow to the remainder of the body, including the brain. Though most organs of the body can tolerate periods with reduced oxygenation, the brain can't. Symptoms such as dizziness and fainting are caused by decreased perfusion of the brain.
Chest Pain
AS causes strain on the heart because it has to pump with more force in order to deliver the same amount of blood to other organs. Long-term effects of this strain cause the heart muscle to amplify, or hypertrophy. Hypertrophy of the heart impairs blood flow to the heart muscle in two ways: More muscle needs to be supplied, and the enlarged muscle compresses the blood vessels that lie on top of it, decreasing available blood flow. This diminished flow to the heart muscle causes localized tissue death, which manifests as chest pain similar to a heart attack.
Decreased Exercise Tolerance
For the same reason AS causes chest pain, it can cause decreased exercise tolerance and difficulty breathing. An enlarged or hypertrophic heart doesn't pump as efficiently as a normal heart, especially against a narrowed aortic valve. Thus, less blood is delivered to the muscles and the lungs, leading to easier fatigue.
References
- CURRENT Diagnosis & Treatment: Surgery, 13e; Johnathon Haft; July 2009
- Merck Manual for Health Care Professionals; "Aortic Stenosis"; Merck Research Laboratories; 2006
