LEFT-VENTRICULAR VOLUME CALCULATIONS USING A MULTIPLANAR TRANSESOPHAGEAL ECHOPROBE - IN-VITRO VALIDATION AND COMPARISON WITH BIPLANE ANGIOGRAPHY

Background Biplane angiographic and transthoracic echocardiographic vo lume calculations have shown to be sufficiently reliable in symmetric hearts; however, they are unreliable in the presence of aneurysmatic d istortions. Multiplane transoesophageal echocardiography offers unobst ructed cross-sectional views of the heart from one stable transducer p osition with the potential of imaging irregular cavity forms more accu rately. It was the purpose of this in vitro study to compare the preci sion of multiplanar transoesophageal echocardiography to that of bipla ne angiography in determining left ventricular volumes, especially in aneurysmatic models. Methods Seven silicon rubber models of the left v entricle from post-mortem specimens (four with aneurysms) were filled with 30 different volumes (range 153-256 ml, 197+/-30 ml). Echocardiog raphic cross-sections (20 degrees rotational steps) were obtained from different transducer positions, utilizing a multiplanar probe with a central rotational axis. Volumes were calculated using the disc-summat ion method. For comparison the same volumes were determined by standar d biplane angiography. The minimum number of echo cross-sections neces sary to optimize precision was analysed by calculating volumes for eac h increasing equidistant rotational step. Results Linear correlation b etween measured volume using a multiplanar transoesophageal echoprobe and true volume was high (r=0.97) and significantly better than for bi plane angiography (r=0.88, P<0.001). Measurement bias and imprecision were also significantly lower with multiplanar echocardiography than w ith biplane angiography (3.9+/-7.1% vs 11.1+/-15.4%, and 2.0+/-3.7% vs 5.9+/-8.3%; P<0.001). Precision of biplane angiographic volume measur ements was significantly influenced by the presence of aneurysmatic di stortions. Multiplanar echo volumes, however, were not influenced by l eft ventricular geometry and transducer positions. Nine echo cross-sec tions provided optimal precision. Conclusions Three-dimensional echoca rdiographic volume calculations using a multiplanar transoesophageal e choprobe and the disc-summation method provide precise measurements un affected by left ventricular geometry and transducer position in an in vitro setting. Standard biplane angiography is significantly less pre cise.