Pulsed Doppler echocardiographic measurement of beat-to-beat changes in stroke volume in dogs

Abstract

Measurement of stroke volume by pulsed Doppler echocardiography has not been validated against a reference method in vivo. We compared Doppler systolic frequency shift integrals with electromagnetic flowmeter stroke volume in seven open-chest dogs. A pulsed Doppler echocardiographic transducer was held on the aortic arch with the sample volume in the ascending aorta. Stroke volume was varied by epinephrine or pentobarbital infusion, fluid administration or inferior vena caval constriction. Linear regression analysis of stroke volume vs Doppler systolic frequency shift integrals revealed strong correlations and intercepts close to zero (r=0.74-0.096, p<0.001). Minor changes in transducer position did not influence Doppler frequency shift integrals substantially. Therefore, pulsed Doppler echocardiography served as an excellent measurement of stroke volume changes in this model. However, serious limitations are presented that may limit its clinical application.