ECHONOMY
Tools for Echocardiographic Calculations
Muhamed Saric, MD, PhD
New York University


Purpose

To
calculate the ratio of pulmonic (Qp) to systemic (Qs) blood flow in
atrial septal defect (ASD), ventricular septal defect (VSD) or patent ductus
arteriosus (PDA) by quantitative Doppler. 
Technical Hints

In ASD and VSD, flow across the
right ventricular outflow tract (RVOT) represents Qp, and the flow across
the left ventricular outflow tract (LVOT) represents Qs. The opposite is
true for PDA. 
Calculator


LVOT 
RVOT 
Diameter (d; in cm) 


Velocity time integral (VTI; in cm) 


Heart rate (beats per minute) 




Answers


LVOT 
RVOT 
Crosssectional area (cm^{2}) 


Stroke volume (mL) 


Flow (L/min) 


Qp : Qs (if ASD or VSD) 


Qp : Qs (if PDA) 


Formulas
LVOT or RVOT Area = (1/2 * d)^{2}
* pi
Stroke Volume = Outflow Tract Area * VTI 
Reference

VargasBarrón J, Sahn DJ, Valdes
Cruz LM, Lima CO, Goldberg SJ, Grenadier E, et al. Clinical utility
of twodimensional Doppler echocardiographic techniques for estimating
pulmonary to systemic blood flow ratios in children with left to right
shunting atrial septal defect, ventricular septal defect or patent ductus
arteriosus.
J Am Coll Cardiol 1984;3:16978.
