DIAMETER AND CROSS-SECTIONAL AREA RELATIONSHIP OF THE HUMAN MAIN PULMONARY-ARTERY - EVALUATED BY EPICARDIAL ECHOCARDIOGRAPHY

Correct assessment of vessel cross-sectional area (CSA) is essential f or reliable cardiac output (CO) measurements by means of pulsed Dopple r echocardiography. In 23 patients who underwent coronary artery bypas s grafting (CABG) the main pulmonary artery CSA and diameter changes w ere assessed by epicardial two-dimensional echocardiography using a 7. 5 MHz cm(2) transducer. Our data indicate that the shape of the pulmon ary artery changes over time. Time averaged CSA ranged from 3.51 to 8. 29 cm(2) (mean 5.04 cm(2); SD 1.3 cm(2)) and the distensibility varied from 13% to 33% (mean 23%; SD 5%). The limits of agreement for the CS A calculated from the most suitable diameter (when assuming vessel cir cularity) and the corresponding traced CSA (reference value) during pe ak systole were -0.16 +/- 0.56 cm(2) (mean +/- 2SD). In this idealized set-up (not clinically implementable) the maximal discrepancy between the calculated and traced CSA was 12% and 17% during peak systole and diastole, respectively. Therefore, a potential error in CO determinat ion is incurred if CSA is assessed from a single diameter.