COMPARISON OF RIGHT-VENTRICULAR VOLUMES BY TRANSTHORACIC AND TRANSESOPHAGEAL ECHOCARDIOGRAPHY IN PATIENTS WITH RIGHT-VENTRICULAR VOLUME OVERLOAD

Assessment of right ventricular volume and function is important in mo st congenital heart diseases before and after corrective or palliative surgery. Since transthoracic echocardiography is often substituted by transesophageal echocardiography in the perioperative setting, it is useful to compare transesophageal echocardiography with transthoracic echocardiography as performed preoperatively. We compared right ventri cular volumes as calculated using these two methods from a four-chambe r view in 21 children and adults with atrial septal defect. For right ventricular end-diastolic volumes of less than 70 ml, and end-systolic volumes of less than 40 ml, a close correlation was found between the techniques (r=0.99 and r=0.91, respectively), with a small degree of underestimation by transesophageal echocardiography. For values larger than 70 ml and 40 ml, respectively, correlation decreased (r=0.41 for end-diastolic volumes and r=0.48 for end-systolic volumes) and undere stimation of volume by transesophageal echocardiography increased. Und erestimation of right ventricular end-diastolic volumes increased with increasing body surface area (r=0.74), and with progressive right ven tricular enlargement (r=0.63). In patients with a body surface area of more than 1m(2), the largest end-diastolic right ventricular length d etermined by transthoracic echocardiography was significantly longer t han that derived by transesophageal echocardiography (p < 0.001), wher eas in smaller patients there was no significant difference between th e two methods (p > 0.1). If right ventricular volumes determined by tr ansthoracic echocardiography using a four-chamber view are substituted by those obtained with transesophageal echocardiography in serial hae modynamic evaluation of patients with atrial septal defect, different correlation equations and, consequently, a different degree of underes timation by transesophageal echocardiography must be considered for la rge and small volumes. This increasing underestimation of larger right ventricular Volumes seems to be based on foreshortening of the long c ross-sectional axis of the right ventricle as seen in the transesophag eal four-chamber view.