title: The influence of transducer position on the M-mode echocardiographic measurement of the left atrial dimension.
abstract: Eighty-five subjects were investigated to see if the left atrial dimension (LAD) determined by M-mode echocardiography varies with different placements of the transducer in the parasternal long-axis view. Satisfactory images from the third and fourth intercostal spaces were obtained in all subjects. A satisfactory image from the second, third and fourth intercostal spaces was obtained in 58 subjects and from the third, fourth and fifth intercostal spaces in 27 subjects. The mean LAD was significantly smaller (P less than 0.001) in the fourth intercostal space than in the third. The mean value obtained from the fifth intercostal space was smaller than that from the fourth. The beam pathway seen on the two-dimensional echocardiogram indicates that the transducer should preferably be placed in the third intercostal space. If the transducer is placed in a lower intercostal space the measured left atrial dimension might be underestimated.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016275:Atrial Function; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006325:Heart Atria / Q000033:anatomy & histology*; D006331:Heart Diseases / Q000175:diagnosis; D006801:Humans; D008297:Male; D008875:Middle Aged; D014159:Transducers