End-diastolic volume is the amount of blood that is in the ventricles before the heart contracts. Doctors use end-diastolic volume to estimate the heart's preload volume and to calculate stroke volume and ejection fraction. These different measurements indicate the health of a person's heart.
In this article, we explain what end-diastolic volume is and how doctors use it. We also discuss some conditions that can affect end-diastolic volume.
End-diastolic volume refers to the quantity of blood in the left or right ventricle at the end of diastole, just before systole starts.
The heart consists of four chambers: two atria and two ventricles. The chambers contain valves that open and close in sequence so that blood flows in one direction through the atria and ventricles.
The veins carry oxygen-poor blood into the right atrium, which connects to the right ventricle. From here, the heart pumps blood into the lungs for oxygenation.
The newly oxygenated blood enters the left atrium and flows into the left ventricle, which contracts, forcing blood up through the aorta. The aorta is the largest artery in the body, and it supplies the entire body with oxygen-rich blood.
Diastole occurs when the heart muscle relaxes, and the chambers fill with blood. Blood pressure decreases during diastole.
Systole occurs when the ventricles contract, pushing blood out of the right ventricle into the lungs and out of the left ventricle to the rest of the body. Blood pressure increases during systole.
Doctors use end-diastolic volume to evaluate the condition of a person's heart and their general health.
A doctor can measure end-diastolic volume using the following tests:
- Echocardiogram. In this noninvasive procedure, doctors use ultrasound technology to create detailed images of a person's heart.
- Left heart catheterization. This procedure involves threading a thin, flexible tube called a catheter through a large blood vessel and into the heart. Doctors can use the catheter to take blood samples and measure the pressure and oxygen content in the four chambers of the heart.
Doctors use end-diastolic volume to calculate several different measurements of heart function, which we discuss below. Sometimes, they specifically use left ventricular end-diastolic volume, which is the amount of blood that is present in the left ventricle before contraction.
Doctors use left ventricular end-diastolic volume to estimate cardiac preload, which is how much the cardiac fibers of the ventricle stretch before contraction. Doctors are unable to test preload directly, so they use end-diastolic volume as a close estimate.
Doctors use both end-diastolic volume and end-systolic volume to calculate stroke volume. End-systolic volume is the amount of blood remaining in the ventricle at the end of systole, after the heart has contracted.
Stroke volume is the quantity of blood that the heart pumps out of the left ventricle with each beat.
The formula for stroke volume is: Stroke volume = end-diastolic volume - end-systolic volume.
According to a large 2017 study, normal stroke volume ranges are:
- 48.2–114.3 milliliters (ml) for people aged 18 to 29 years
- 39.1–98.5 ml for people aged 30 to 59 years
- 39.7–115.3 ml for people aged 60 years or older
Ejection fraction refers to the proportion of blood that leaves the left ventricle during systole relative to the end-diastolic volume. Essentially, it is the percentage of blood that the heart pumps out of the left ventricle during each beat.
Doctors use ejection fraction to determine how well the heart is pumping blood and to help diagnose heart failure.
The calculation for ejection fraction is: Ejection fraction = (stroke volume / end-diastolic volume) x 100.
According to the American Heart Association, a healthy ejection fraction ranges between 50% and 70%.
Certain health conditions can affect end-diastolic volume. These include:
Cardiomyopathy is an umbrella term for medical conditions that affect the heart muscle. These conditions can cause the heart muscle to thicken, enlarge, or lose its elasticity.
Cardiomyopathy affects the heart's ability to pump blood around the body, which can lead to an irregular heartbeat, heart failure, and other serious complications.
There are several different types of cardiomyopathy. In people with dilated cardiomyopathy, the ventricles become enlarged, which increases the end-diastolic volume.
Enlargement of the heart muscle can cause the ventricle walls to thicken, causing a condition called hypertrophic cardiomyopathy. This thickening can affect blood flow out of the left ventricle, which can lead to an increase in end-diastolic volume.
Mitral valve regurgitation
Mitral valve regurgitation occurs when blood leaks backward through the mitral valve, which connects the left atrium and ventricle.
The left atrium may enlarge to accommodate the extra blood leaking through the mitral valve. An enlarged left atrium can lead to complications, such as atrial fibrillation, an irregular heartbeat, heart failure, and stroke.
End-diastolic volume is a useful indicator of a person's heart health. Doctors use end-diastolic volume to estimate preload and calculate the heart's stroke volume and ejection fraction.
Certain conditions may affect end-diastolic volume, including cardiomyopathy and mitral regurgitation.