Echocardiographic Indices of Doppler Flow Patterns Compared with MRI or Angiographic Measurements to Detect Significant Coarctation of the Aorta

Abstract

Evaluation for the presence and severity of coarctation of the aorta (CoA) by two-dimensional echocardiography alone can be difficult. The purpose of this study was to use Doppler velocity and pressure gradient half-time in systole and diastole to estimate CoA severity. Doppler echocardiograms of children with suspected CoA and either an aortic angiogram or thoracic magnetic resonance imaging (MRI) performed within 1 month of the echocardiogram were evaluated. Patients with patent ductus arteriosus, significant aortic insufficiency, long tubular CoA, or CoA outside the thorax were excluded. Measured Doppler variables, indexed for heart rate, included systolic velocity half-time (sVHTi), diastolic velocity half-time (dVHTi), systolic pressure half-time (sPHTi), and diastolic pressure half-time (dPHTi). For each of these variables, sensitivity and specificity to detect a significant CoA were determined. A significant CoA was defined as a ratio of the CoA diameter to the diaphragmatic aortic diameter of < 0.5 as imaged by MRI or angiography. Indexed systolic velocity and pressure half-times were found not to be significant predictors for CoA. For the Doppler parameter dVHTi, using a critical value of > 200 msec indexed, we found a positive predictive value of 87% and a negative predictive value of 80%. The parameter dPHTi, using a critical value of > 75 msec indexed, demonstrated positive and negative predictive values of 92% and 79%, respectively. Measurement of dVHTi is a useful predictor for significant CoA, but the parameter dPHTi has an improved positive predictive value for detection of significant CoA. Systolic measurements of velocity or pressure half-times are not adequate to assess severity of CoA.