ONLINE ESTIMATION OF STROKE VOLUME BY MEANS OF ECHOCARDIOGRAPHIC AUTOMATED BORDER DETECTION IN THE CANINE LEFT-VENTRICLE

Echocardiographic automated border detection (ABD) is a new on-line te chnique that can determine the interface between blood and myocardial tissue and calculate left ventricular (LV) cavity area in real time. T he objective of this study was to determine whether ABD measurements o f the LV cavity area could be used to estimate LV stroke volume at bas al conditions and during large changes in LV stroke volume induced by inferior vena caval occlusions in an open-chest canine model. Seven do gs had LV stroke volume measured by electromagnetic flow from the asce nding aorta with epicardial recordings of ABD echocardiographic area a t the midventricular short-axis level. Simultaneous beats of stroke vo lume were recorded along with ABD echo area during baseline apnea and during IVC occlusions. Neither ABD echo stroke area nor stroke volume varied significantly during apnea baseline. Changes in stroke area wer e closely correlated with changes in stroke volume for 540 matched bea ts from 24 IVC occlusions: R = 0.93, standard error of the estimate = 5%, y = 0.92x + 0.4 (p < 0.001). Echocardiographic ABD appears to be a promising new on-line method of determining rapid alterations in LV s troke volume; it also has potential applications to multiple investiga tional and clinical settings.