Enter the Left Ventricular Outflow Tract (LVOT) diameter, the Velocity Time Integral (VTI), and the heart rate into the calculator to determine the cardiac output. This calculator uses echocardiographic measurements to estimate the volume of blood the heart pumps through the circulatory system in a minute.

Cardiac Output Echo Formula

The following formula is used to calculate the cardiac output using echocardiographic measurements:

CO = (π * (LVOTD / 2)^2 * VTI * HR) / 1000

Variables:

  • CO is the cardiac output (L/min)
  • LVOTD is the Left Ventricular Outflow Tract Diameter (cm)
  • VTI is the Velocity Time Integral (cm)
  • HR is the heart rate (beats per minute)

To calculate the cardiac output, first measure the LVOT diameter and VTI using echocardiography. Then, multiply the LVOT area by the VTI and the heart rate. Finally, divide the result by 1000 to convert it to liters per minute (L/min).

What is Cardiac Output?

Cardiac output is the volume of blood the heart pumps per minute. It is a critical parameter in assessing cardiac function and is used to diagnose and monitor patients with heart conditions. Cardiac output is determined by the stroke volume (the amount of blood pumped by the left ventricle of the heart in one contraction) and the heart rate (the number of heartbeats per minute).

How to Calculate Cardiac Output?

The following steps outline how to calculate the Cardiac Output using echocardiographic measurements.

  1. Measure the LVOT diameter (LVOTD) in centimeters using echocardiography.
  2. Measure the VTI in centimeters using Doppler echocardiography.
  3. Record the patient’s heart rate (HR) in beats per minute.
  4. Calculate the LVOT area using the formula: Area = π * (LVOTD / 2)^2.
  5. Multiply the LVOT area by the VTI and the HR to get the stroke volume per minute.
  6. Divide the stroke volume per minute by 1000 to convert it to liters per minute (L/min) to get the cardiac output (CO).
  7. Use the calculator above to verify your results.

Example Problem:

Use the following variables as an example problem to test your knowledge.

LVOT Diameter (LVOTD) = 2 cm

Velocity Time Integral (VTI) = 20 cm

Heart Rate (HR) = 75 bpm