Use of Intravascular Carbon Dioxide Gas to Demonstrate Interatrial Septal Defects

¹ From the Departments of Medicine, Radiology and Physiology, School of Medicine, Temple University, Philadelphia, Pennsylvania

Carbon dioxide gas injected intravenously will safely demonstrate experimental interatrial defects using a cinefluorographic technique. Under these experimental conditions gas may be demonstrated in the left atrium and ventricle. At the time gas passes through the defect the systemic pressure rises. In the absence of a defect the systemic pressure falls. Left ventricular systolic pressure levels parallel the changes in systemic blood pressure. The presence of gas in the right atrium elevates pressure in the left atrium only a few millimeters of mercury in controls and in the presence of interatrial defects.