An echocardiogram, often called an “echo,” is a non-invasive medical imaging technique that uses high-frequency sound waves to generate dynamic pictures of the heart. This diagnostic tool allows healthcare providers to visualize the heart’s structure and function in real-time motion. The sound waves travel through the chest and bounce off the heart structures to create moving images. This safe procedure provides a comprehensive assessment of the heart muscle, its chambers, and the surrounding blood vessels.
What the Echocardiogram Test Involves
The standard echocardiogram, known as a transthoracic echo, is typically ordered for symptoms such as unexplained shortness of breath, chest pain, or an abnormal heart sound like a murmur. The procedure requires minimal preparation and generally takes less than an hour. During the test, the patient lies on their left side while a technician applies a water-based gel to the chest to transmit the sound waves.
A handheld device, called a transducer, is pressed against the chest to capture different views of the heart. This transducer emits sound waves and records the returning echoes, translating them into moving images on a screen.
The resulting images reveal the size and shape of the heart’s four chambers, indicating if the walls are thickened or chambers are enlarged. The echo also visualizes the heart valves, checking for conditions where valves are too narrow (stenosis) or are leaking blood backward (regurgitation). Furthermore, the test uses Doppler technology, which measures the speed and direction of blood flow through the heart and vessels, assisting in the diagnosis of structural and functional abnormalities.
Defining Ejection Fraction and Its Measurement
The specific measurement that an echocardiogram provides regarding the heart’s pumping action is called the Ejection Fraction (EF). Ejection Fraction is defined as the percentage of blood that the heart pumps out of a chamber with each contraction. Since the left ventricle is the heart’s main pumping chamber responsible for sending oxygen-rich blood to the entire body, EF typically refers to the Left Ventricular Ejection Fraction (LVEF).
To understand this percentage, consider the blood volume within the ventricle. Before contraction, the left ventricle is filled with blood, known as the end-diastolic volume (EDV). When the heart squeezes during systole, it pushes out a portion of that blood, which is called the stroke volume (SV).
The Ejection Fraction is calculated by dividing the stroke volume by the end-diastolic volume and multiplying by 100. The heart does not eject all the blood it holds, so a normal EF is always a percentage, not 100%. For instance, an EF of 60% means that 60% of the blood that filled the left ventricle was pumped out.
The echocardiogram calculates this percentage using advanced imaging techniques. The method recommended by professional cardiology societies is the Modified Simpson method, also known as the biplane method of disks. This technique involves tracing the inner border of the left ventricle in two different views during both the filled (diastolic) and contracted (systolic) states. The software uses these tracings to estimate the volumes of the ventricle at both points, providing the necessary numbers to calculate the Ejection Fraction.
Interpreting Ejection Fraction Results
The numerical result of the Ejection Fraction is a direct indicator of the heart’s systolic function and guides diagnosis and treatment for various heart conditions. For a healthy adult, a Left Ventricular Ejection Fraction is considered normal when it falls between 50% and 70%. This range confirms that the heart is pumping a sufficient portion of its blood volume to meet the body’s needs.
A result that is slightly below this range, between 41% and 49%, is classified as mildly reduced. This finding may suggest early damage to the heart muscle or a risk for developing heart failure, even if the patient is not yet experiencing noticeable symptoms. Healthcare providers often monitor patients in this range closely and may recommend preventative therapies or lifestyle adjustments.
If the Ejection Fraction falls to 40% or lower, it suggests the presence of heart failure with reduced ejection fraction (HFrEF). This reduced pumping capacity means the heart cannot circulate enough blood to adequately supply the body’s organs, leading to symptoms like fatigue and shortness of breath. The lower the EF dips below 40%, the more impaired the heart function is considered, influencing the urgency and type of medical treatment prescribed.
It is possible for the EF to measure higher than the normal range, sometimes exceeding 75%. An unusually high Ejection Fraction can be a sign of underlying conditions, such as hypertrophic cardiomyopathy. In this condition, the heart muscle walls become thickened and stiff, which interferes with the heart’s ability to relax and fill properly. Therefore, the Ejection Fraction is interpreted by cardiologists alongside other clinical data and test results to form a complete picture of heart health.