Enter your LVOT Diameter, LVOT VTI, and Heart Rate to calculate Stroke Volume and Cardiac Output. The Stroke Volume Calculator uses echocardiographic measurements to determine how much blood your heart pumps per beat (in mL) and total cardiac output (in L/min).
Stroke Volume
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LVOT Cross-Sectional Area
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Cardiac Output
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Cardiac Output
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Stroke volume is the amount of blood ejected by the left ventricle with each heartbeat, measured in millilitres (mL). It reflects the pumping efficiency of the heart and is a key parameter in cardiac assessment. Normal stroke volume at rest is approximately 60–100 mL per beat.
Stroke volume is calculated as the product of the LVOT (Left Ventricular Outflow Tract) cross-sectional area and the LVOT velocity time integral (VTI): SV = π × (LVOT diameter / 2)² × LVOT VTI. This Doppler-based method is widely used in clinical echocardiography.
The LVOT VTI (Velocity Time Integral) represents the distance blood travels across the LVOT during one systolic ejection, expressed in centimetres. It is measured by tracing the pulsed wave Doppler signal obtained from the apical long axis or 5-chamber view. Normal values are typically 15–25 cm.
The LVOT diameter is measured in the parasternal long axis view during mid-systole, just below the aortic valve. It is typically around 2 cm in adults and is used to calculate the LVOT cross-sectional area.
Cardiac output (CO) is the total volume of blood pumped by the heart per minute. It is calculated by multiplying stroke volume by heart rate: CO = HR × SV. For example, a stroke volume of 60 mL with a heart rate of 100 bpm gives a cardiac output of 6,000 mL/min (6.0 L/min).
Normal resting cardiac output in adults ranges from approximately 4.0 to 8.0 L/min. Values may vary based on body size, fitness level, and physiological state. Cardiac index (cardiac output divided by body surface area) is used when adjusting for body size.
The LVOT Doppler method is non-invasive, reproducible, and does not require contrast agents or radiation. It is considered the gold standard for echocardiographic stroke volume assessment and is widely validated against invasive thermodilution measurements.
Heart rate does not directly determine stroke volume; rather, stroke volume depends on preload, afterload, and myocardial contractility. However, very high or very low heart rates can indirectly affect filling time and therefore stroke volume. Cardiac output is the product of both stroke volume and heart rate.