LEFT ATRIAL SIZE AND FUNCTION - ASSESSMENT USING ECHOCARDIOGRAPHIC AUTOMATIC BOUNDARY DETECTION

Objective-To evaluate the waveforms of left atrial area changes obtain ed by automated boundary detection with newly developed acoustic quant ification technology. Design-Ah subjects had measurements of left atri al areas taken in the apical four chamber, parasternal long axis, and parasternal short axis views using both conventional echocardiographic methods and automatic boundary detection on two occasions separated b y at least a week. On the second visit measurements were also repeated in healthy volunteers after acute intravenous volume loading with 1 L itre of saline over 2-5 minutes. Setting-A university medical school e chocardiographic laboratory. Subjects-12 healthy male volunteers and 8 patients with cardiac disease (5 with congestive heart failure, 1 wit h mitral stenosis, and 2 with hypertensive left ventricular hypertroph y, and dilated left atria). Results-There was close correlation betwee n conventionally derived left atrial areas and those obtained by autom atic boundary detection, particularly in the apical four chamber view (r = 0.98). Both inter and intra observer variabilities (coefficient o f variation) for left atrial areas measured by automatic boundary dete ction were good (4.7-14.2% and 8.1-18.6% respectively). The reproducib ility (coefficient of variation) for derived indices of left atrial fu nction, however, was much poorer (10.4-104.8% and 12.5-88% respectivel y). After acute volume loading significant increases in left atrial ar ea were observed at all stages in the cardiac cycle. Conclusions-These data demonstrate that although the reproducibility of left atrial fun ctional indices is poor, instantaneous left atrial cavity measurements with automatic boundary detection are reproducible. This suggests tha t automatic boundary detection may assist in serial non-invasive measu rement of left atrial size to assess disease states and treatments.