QUANTITATIVE 3-DIMENSIONAL RECONSTRUCTION OF ANEURYSMAL LEFT-VENTRICLES - IN-VITRO AND IN-VIVO VALIDATION

Background Current two-dimensional (2D) echocardiographic measures of left ventricular (LV) volume are most limited by aneurysmal distortion , which restricts application of simple geometric models that assume s ymmetrical shape. 2D methods also fail to provide separate volumes of the aneurysm and nonaneurysmal residual LV cavity, which could help as sess the stroke volume wasted by dyskinesis and the potential residual LV body to guide surgical approaches and predict their outcome. Three -dimensional (3D) echocardiographic reconstruction has potential advan tages for assessing aneurysmal left ventricles because it is not depen dent on geometric assumptions, does not require standardized views tha t may exclude portions of the aneurysm, and can potentially measure se parate aneurysm and nonaneurysm cavity volumes of any shape. The purpo se of this study was first, to validate the accuracy of 3D echocardiog raphic reconstruction for quantifying total LV and separate LV body an d aneurysm volumes in vitro so as to provide direct standards for the separate volumes; and second, to determine the feasibility and accurac y of 3D echocardiographic reconstruction for quantifying the total vol ume and function of aneurysmal left ventricles in an animal model, pro viding a reference standard for instantaneous LV volume. Methods and R esults A recently developed 3D system that automatically combines 2D i mages and their locations was applied (1) to reconstruct 10 aneurysmal ventricular phantoms and 12 gel-filled autopsied human hearts with an eurysms, comparing cavity volumes (total and aneurysm) to those measur ed by fluid displacement; and (2) to reconstruct the left ventricle du ring 19 hemodynamic stages in four dogs with surgically created LV ane urysms, comparing total volumes with actual instantaneous values measu red by an intracavitary balloon attached to an external column for val idation and also calculating the stroke volume wasted by aneurysmal dy skinesis. 3D reconstruction reproduced the distorted aneurysmal LV sha pes. In vitro, calculated volumes (aneurysm, nonaneurysm, and total) a greed well with actual values, with correlation coefficients of .99 an d SEEs of 3.2 to 6.1 cm(3) for phantoms and 3.4 to 4.2 cm(3) for autop sied hearts (mean error, <4% for both). In vivo, LV end-diastolic, end -systolic, and stroke volumes as well as ejection fraction calculated by 3D echocardiography correlated well with actual values (r=.99, .99, .95, and .99, respectively) and agreed closely with them (SEE=4.3 cm( 3), 3.5 cm(3), 1.7 cm(3), and 2%, respectively). The stroke volumes wa sted by the aneurysm were -20.1+/-19.3% of LV body (nonaneurysm) strok e volume. Conclusions Despite distorted ventricular shapes, a recently developed 3D echocardiographic system and surfacing algorithm can acc urately reconstruct aneurysmal left ventricles and quantify total LV v olume (validated in vivo and in vitro) as well as the separate volumes of the aneurysm and residual LV body (validated in vitro). This shoul d improve our ability to evaluate such ventricles and guide surgical a pproaches.