Estimation of Systolic and Diastolic Left Ventricular Blood Flow From Derivatives of Transesophageal Echocardiographic 3D Volume Curves in Cardiac Surgery Patients: A Proof-of-Concept Study.

Objectives
To examine whether estimates of peak global systolic (S') and diastolic (E') left ventricular (LV) flow rates based on 3D echocardiographic volumes are feasible and match physiology.Methods
In this retrospective feasibility study, we included patients undergoing major cardiac surgery. S' and E' were derived from 190 patients by taking the first derivative of the volume-time relationship of 3D ecg-gated transesophageal echocardiography (TEE) images. To examine the quality of images upon which the estimates of flow were based we correlated intraoperative 3D TEE and preoperative 2D transthoracic echocardiography (TTE) volumes. As a proof-of-concept, we then correlated S' flow with stroke volume and S' and E' were compared by valve pathology.Results
In each of the 190 images, S' and E' were derived. There was good correlation between 1) the ejection fraction (EF) of 3D LV images obtained intraoperatively by TEE and preoperatively by TTE (Pearson's r = 0.65) and also 2) S' and stroke volume (Pearson's r = 0.73). Patients with aortic or mitral regurgitation showed higher S' than patients without valve pathologies (-315 mL/s [95% CI -388 mL/s to -264 mL/s] = 0.001, -319 mL/s [95% CI -397 mL/s to -246 mL/s] = 0.001 vs -242 mL/s [95% CI -300 mL/s to -196 mL/s]). These patients also showed higher E' than patients without valve pathologies (302 mL/s [95% CI 237 mL/s to 384 mL/s] = 0.006, 341 mL/s [95%CI 227 mL/s to 442 mL/s] = 0.001 vs 240 mL/s [95%CI 185 mL/s to 315 mL/s]). Patients with aortic stenosis showed no difference in S' or E' (-263 mL/s [95%CI -300 mL/s to -212 mL/s] = 0.793, 255 mL/s [95%CI 188 mL/s to 344 mL/s] = 0.400).Conclusions
Estimates of global peak systolic and diastolic LV flow based on 3D TEE are feasible, promising, and match valve pathologies.