Doppler Cardiac Output
Use LVOT diameter, LVOT VTI, and heart rate to compute stroke volume and cardiac output. Ensure measurements are obtained in the same cardiac cycle for accuracy.
Measured in parasternal long-axis, mid-systole.
Trace pulse-wave Doppler envelope at LVOT from apical 5-chamber.
How to Use This Calculator
Measure LVOT diameter
Use parasternal long-axis view, inner-edge to inner-edge, mid-systole. Small deviations significantly influence calculated area.
Acquire LVOT VTI
From apical 5-chamber, align pulsed Doppler cursor with LVOT flow and trace the entire systolic envelope.
Insert heart rate
Use simultaneous heart rate to calculate flow per minute. Combine with BSA to derive cardiac index if needed.
Formula
LVOT area = π × (LVOT diameter ÷ 2)2
Stroke volume = LVOT area × LVOT VTI
Cardiac output = Stroke volume × Heart rate ÷ 1000
Outputs are in cm², mL, and L/min respectively.
Full Description
Doppler echocardiography quantifies cardiac output by combining LVOT geometry with flow velocity. Accurate diameter measurement is crucial due to squared dependence. Use this technique during hemodynamic assessments, valve disease evaluation, and perioperative monitoring. Compare with invasive thermodilution or Fick measurements when available.
Frequently Asked Questions
How sensitive is the calculation to LVOT diameter?
Small errors significantly affect stroke volume. Use zoomed, high-quality images and repeat measurements for accuracy.
What if LVOT is elliptical?
Standard calculation assumes circular LVOT. 3D echo or CT can refine area estimation in patients with aortic root pathology.
Can arrhythmias affect results?
Yes. Average multiple beats in atrial fibrillation or frequent ectopy. Align measurement timing with hemodynamic sampling if comparing to invasive data.
How do I obtain cardiac index?
Calculate BSA (Mosteller) and divide cardiac output by BSA (CI = CO ÷ BSA). Many hemodynamic calculators provide both metrics.