PULMONARY VASCULAR DILUTION CURVES RECORDED BY EXTERNAL DETECTION IN THE DIAGNOSIS OF LEFT-TO-RIGHT SHUNTS

Abstract

A simple technique for the recording of indicator-dilution curves from the pulmonary vascular bed and its application to the detection of left-to-right circulatory shunts is described. A gamma-emitting isotope, I131- labelled diodrast, was injected intravenously and its activity in the pulmonary vascular bed determined with a scintillation detector placed over the upper lung field. In the 17 patients in whom the presence of left-to-right shunt was subsequently proved, the descending limb was selectively prolonged, and simple analysis of the curves in a total of 33 patients allowed determination of the presence or absence of a shunt. The advantages of placing the detector over the lung fields as compared to the pre-cardium are described. The clinical value of this simple technique in the study of patients following cardiac operations and in the screening of patients with heart murmurs of uncertain etiology is discussed.