Transthoracic three-dimensional echocardiography for the assessment of straddling tricuspid or mitral valves

Background: The advent of 3D echocardiography has provided a technique whic h, potentially, could afford significant additional information over conven tional cross-sectional echocardiography in the assessment of patients with straddling atrioventricular valves prior to surgical correction. Methods. E ight patients, aged from 1 month to 9.2 years, were examined with 3D echoca rdiography. All but three had discordant ventriculoarterial connections or double outlet right ventricle. Data suitable for reconstruction was acquire d with transthoracic scanning. Right and left ventricular volumes were calc ulated in the 3D dataset. Results: 3D echocardiography proved capable of de fining the exact degree of straddling by imaging the proportion of tension apparatus attached to either side of the ventricular septum. It was able al so to display the atrioventricular junction "en face", thus permitting iden tification of the precise site of insertion of the muscular ventricular sep tum relative to the atrioventricular junction. This made it possible first, to calculate the degree of valvar override, and second, to predict the loc ation of the penetrating atrioventricular bundle. End-diastolic volume of t he right ventricle in those with straddling tricuspid valves was 73 (61-83) % of normal, and, of the left ventricle in those with mitral valvar straddl ing 71 (40-97)% of normal. Conclusions: 3D echocardiography can aid in plan ning the optimal surgical procedure in patients with straddling or overridi ng atrioventricular valves, as it provides diagnostic information superior to standard cross-sectional techniques. It also allows for exact measuremen t of the volumes of the respective ventricles.