Objective To develop a multiplane transesophageal echocardiography three-dimensional reconstruction system in LVM determination and compare it with M-mode echocardiographic methods.Methods Epicardial M-mode and multiplane transesophageal echocardiography were performed in 18 open-chest dogs before and after coronary artery ligation and LVM were calculated by two methods. Penns formula was based on M-mode images and 3-DE method was based on reconstruction of 18 cross-sectional images of the left ventricle, which were obtained by rotating the phased array of multiplane transesophageal echocardiography probe, into three dimensional format. These results were compared with the actual weight of LVM.Results LVM estimated by 3-DE correlated highly with the actual value of LVM both before and after coronary artery ligation (r=0.95, SEE=2.1 g; and r=0.98, SEE=2.2 g, respectively); on the other hand, the correlation of LVM measured by Penns convention correlated highly with the actual weight before coronary artery ligation (r=0.91, SEE=3.6 g), but differed significantly from that after coronary artery ligation (r=0.63, SEE=7.9 g).Conclusion 3-DE is able to quantitatively assess LVM with high accuracy both in normal hearts and in hearts with regional wall motion abnormalities. Therefore, it is superior to M-mode echocardiography in measuring LVM in patients with combined hypertension and coronary artery disease.