Understanding Left Ventricular Ejection Fraction
What Is the Ejection Fraction?
When we discuss “ejection fraction,” this is the term used to discuss the amount of oxygenated and deoxygenated blood that leaves the heart with each contraction. The heart pumps blood in a process known as the cardiac cycle. It is during the cardiac cycle that the heart valves will relax and contract to allow the flow of blood from the atria to the ventricles, and eventually to the rest of the body.
With the second heart beat the blood is ejected from the left ventricle into the aorta. The way in which the cardiac cycle operates, it is while the heart is resting between beats, blood will be entering the ventricles to be ejected again. As not all of the blood is ejected from the heart with the contraction of the ventricles, the “ejection fraction” is the amount that is ejected after the ventricle is filled.
The main ventricle of the heart valve is the left ventricle, the ejection fraction of the heart is measured here. Therefore, it can be stated that the normal range for the left ventricle (LV) ejection fraction is 55 to 70 percent.
What Does the Ejection Fraction Tell Us
The left ventricular ejection fraction (LEVF) might seem like an arbitrary measurement, but it can tell us a lot about the health of a person’s heart. There are certain heart conditions that can affect the way in which the heart muscle contracts. If the heart is not ejecting enough blood, there is not enough oxygen reaching the tissues. The natural physiological response would be to have the heart pump faster. However, this can be quite damaging in a heart that is already weak. If the LEVF is below 55 percent, a physician can diagnose a person having a condition such as left ventricle heart failure.
Abnormal Results: How LEVF Can Be Altered
In previous studies completed, researchers have discovered that there is a higher risk of mortality in people with a lower LEVF. This is a ejection fraction that is less than 55 percent. The LEVF can be measured by various tests such as an echocardiogram using sound waves to see the flow of blood or by a cardiac catheter. It is important to know the ejection fraction for diagnosis and treatment of heart conditions.
Abnormal results for the LEVF can be obtained in various situations that affect the heart muscle. One of the most common heart conditions that alters the ejection fraction is a myocardial infarction or heart attack. A heart attack can damage the muscle and innervation to the heart resulting in an irregular heartbeat. Thus the damaged left ventricle is unable to properly eject the normal amount of blood.
Another medical condition in which it is possible to have an abnormal ejection fraction is congestive heart failure (CHF). Since the heart muscle is weakened over time in congestive heart failure, the amount of blood ejected is also reduced. Someone with CHF may have a left ventricular ejection fraction below 55 percent.
eMedicine: Congestive Heart Failure
American Heart Association: Ejection Fraction Heart Failure Measurement