ECHOCARDIOGRAPHIC PITFALLS IN THE PREMATURE WITH LARGE PATENT DUCTUS ARTERIOSUS

Abstract

The ultrasound-derived ratio of left atrial to aortic root dimensions (LA/Ao) is used commonly to assess the presence and magnitude of left to right shunting through the PDA in prematures. The results of the present study emphasize the hazards of overreliance on this echo index. Thus, seven of thirty-one consecutive premature infants with severe respiratory distress syndrome and clinical and radiographic evidence of significant ductal left to right shunting were found to have normal LA/Ao ratios, as well as normal absolute left atrial dimensions. The LA/Ao ratios remained normal in these respirator-bound infants despite clinical signs of severe cardiac decompensation. In four of these infants the PDA was ligated surgically, while in two indomethacin was effective. The remaining infant responded to digitalis, diuretics, and fluid restriction, and ultimately closed her PDA spontaneously. Abolition of ductal left to right shunting did not consistently change the LA/Ao ratios or absolute left atrial dimensions in this group. A major finding in these infants was the detection of abnormally enlarged left ventricular end diastolic dimensions in the presence of normal left atrial dimensions. Thus, maximum diagnostic accuracy can be achieved only by a comprehensive echocardiographic evaluation that combines analysis of both atrial and ventricular dimensions since the former, when used alone, may be misleading.