Validation of the accuracy of both right and left ventricular outflow volume determinations and semiautomated calculation of shunt volumes through atrial septal defects by digital color doppler flow mapping in a chronic animal model

OBJECTIVES: The aim of the present study was to quantitate shunt flow volumes through atrial septal defects (ASDs) in a chronic animal model with surgically created ASDs using a new semiautomated color Doppler flow calculation method (ACM). BACKGROUND: Because pulsed Doppler is cumbersome and often inappropriate for color flow computation, new methods such as ACM are of interest. METHODS: In this study, 13 to 25 weeks after ASDs were surgically created in eight sheep, a total of 24 hemodynamic states were studied at a separate open chest experimental session. Electromagnetic (EM) flow probes and meters were used to provide reference flow volumes as the pulmonary and aortic flow volumes (Q(p) and Q(s)) and shunt flow volumes (Q(p) minus Q(s)). Epicardial echocardiographic studies were performed to image the left and right ventricular outflow tract (LVOT and RVOT) forward flow signals. The ACM method digitally integrated spatial and temporal color flow velocity data to provide stroke volumes. RESULTS: Left ventricular outflow tract and RVOT flow volumes obtained by the ACM method agreed well with those obtained by the EM method (r = 0.96, mean difference = 0.78 ± 1.7 ml for LVOT and r = 0.97, mean difference = -0.35 ± 3.6 ml for RVOT). As a result, shunt flow volumes and Q(p)/Q(s) by the ACM method agreed well with those obtained by the EM method (r = 0.96, mean difference = -1.1 ± 3.6 ml/beat for shunt volumes and r = 0.95, mean difference = -0.11 ± 0.22 for Q(p)/Q(s)). CONCLUSIONS: This animal study, using strictly quantified shunt flow volumes, demonstrated that the ACM method can provide Q(p)/Q(s) and shunt measurements semiautomatically and noninvasively.