Nuklearmedizinische Shunt-Bestimmung beim Ductus arteriosus Botalli

Abstract

ln 9 patients with patent ductus arteriosus, quantification of left-to-right shunt was performed with dye dilution curves after peripheral injection and with radionuclide ventriculography. The study was repeated within 7 days after successful transluminal occlusion of the ductus with an lvalon®-plug. Reproducubility of the method could be studied in one patient in whom reopening of the ductus occurred. Dye dilution curves were analyzed using the method of Carter et al. (2). Radionuclide ventriculography was performed as a combined first-pass and equilibrium study: effective stroke volume was derived from the first pass of the tracer through the heart; during the equilibrium phase left ventricular ejection fraction (EF) and left ventricular enddiastolic volume (EDV) were evaluated. The difference between total left ventricular stroke volume (product of EF and EDV) and effective stroke volume was taken as shunt volume. This volume as a fraction of total left ventricular-stroke volume resulted in percent left-to-right shunt. The sensitivity of the dye technique was 78%; a quantification of the shunt lesion was possible in 55% of all cases (shunt greater than 35%). The sensitivity of the radionuclide technique was 90%. The severity of the lesion could not be determined in one patient with a minimal shunt. After successful occlusion of the ductus, dye dilution curves normalized in all cases. Radionuclide ventriculography showed normalization in all but one patient. This patient with concomitant mitral regurgitation still showed moderate left ventricular volume overload. After occlusion, left ventricular enddiastolic volume significantly decreased (from 224 to 181 ml, p <0.05), effective cardiac output increased (from 6186 to 7476 ml, p <0.01) and ejection fraction remained unchanged (55 vs. 51 %). It is concluded, that combined first-pass and equilibrium radionuclide ventriculography permits reliable determination of left-to-right shunts in patients with patent ductus arteriosus. It provides important additional information concerning the follow-up of EF, EDV and cardiac output. This method is superior to dye dilution techniques