Untitled

Abstract

Summary: The present investigation was undertaken to assess a new scintigraphic method for the diagnosis of left-ta-right shunts due to atrial septal defect based on the differing stroke volumes of left and right ventricles and to compare it with oxymetric data. Radionuclide ventriculography was carried out after idjection. of 20 mCi 99mtechnetium-labeled red blood cells. TiI:ne-activity curves were obtained from the left and right ventricular regions, and the ratio (A) of end-diastolicend-systolic count rate differences for the left and right ventricles was calculated. The left-to-right shunt (in percent ofthe-pulmonary flow rate) is then giveri as 100 X (I -A/1.43); 1.43 being the previously deterrrlined mean value of A in 66 normal patients. In 16 pafients with an atrial septal defect and/or partial anomalous pulmonary venous connection a correlation of r = 0.81 was found between those shunts determined by the scintigraphic method and those calculated by oxymetric data. The specificity of the method and the sensitivity in detecting left-to-right shunts exceeding 30% are high. The method is practical and already widely used for determination of ejection fraction, end-diastolic volufne and other factors. The combination of this tec~nique