Doppler Echo Cardiac Output Calculator

About Doppler echo cardiac output

Cardiac output is the volume of blood pumped by the heart each minute. Doppler echocardiography provides a noninvasive way to estimate it by measuring flow through the left ventricular outflow tract, or LVOT. This calculator follows the standard continuity-based approach: determine the LVOT cross-sectional area, multiply that area by the Doppler velocity time integral to obtain stroke volume, then multiply stroke volume by heart rate to obtain cardiac output. LVOT area is modeled as a circle. The formula is pi multiplied by the square of one-half the LVOT diameter. Area in square centimeters multiplied by VTI in centimeters produces cubic centimeters, numerically equivalent to milliliters. That result is stroke volume. Multiplying milliliters per beat by beats per minute and dividing by one thousand gives liters per minute. The calculator shows each intermediate value so the source of the final result remains visible. Measurement quality has a major effect on accuracy. Because diameter is squared, a small LVOT diameter error produces a larger area and output error. Diameter is generally measured inner edge to inner edge at the recommended phase and location. VTI should come from a well-aligned pulsed-wave Doppler tracing with the sample volume positioned appropriately. An irregular rhythm may require averaging several representative beats. Heart rate should correspond to the beats used for the VTI measurement. Cardiac output is interpreted in context rather than against one universal target. Body size, age, pregnancy, fever, anemia, exercise, medications, preload, afterload, valve disease, and ventricular function can all influence output. Clinicians often divide cardiac output by body surface area to obtain cardiac index, which allows more useful comparison between people of different sizes. This tool reports unindexed output because body surface area is not one of its inputs. This calculator is intended for education and arithmetic support, not independent diagnosis or treatment. It cannot assess image quality, identify an incorrect Doppler envelope, or account for significant LVOT obstruction, shunts, or valve pathology. A qualified clinician should interpret echocardiographic data together with symptoms, examination, other measurements, and the complete study. If a value appears unexpected, verify units, acquisition timing, tracing selection, and diameter placement before drawing a clinical conclusion.

Doppler cardiac output examples

How to calculate Doppler cardiac output

1. Enter the heart rate corresponding to the Doppler beats used for measurement.
2. Enter the LVOT diameter in centimeters from the echocardiographic study.
3. Enter the traced LVOT velocity time integral in centimeters.
4. Select Calculate Cardiac Output and review the area, stroke volume, and output.

Doppler cardiac output FAQ