EVALUATION OF AORTIC COARCTATION AFTER SURGICAL REPAIR - ROLE OF MAGNETIC-RESONANCE-IMAGING AND DOPPLER ULTRASOUND

Objective-To compare the usefulness of magnetic resonance imaging (MRI ) and Doppler ultrasound with that of cross sectional echocardiography and oscillometric blood pressure measurement for the evaluation of ao rtic coarctation after surgical repair. Design-Prospective study. Aort ic diameters measured by cross sectional echocardiography, MRI, and an giography (selected cases) and functional data determined by physical examination, oscillometric blood pressure measurement, and continuous wave Doppler. Setting-Tertiary referral centre. Patients-40 patients a ged 2-28 years (mean 10.6 years) who had had surgical correction of ao rtic coarctation (mean follow up 5-7 years). Results-In all patients M RI gave diameter measurements of the aortic arch and the thoracic aort a whereas in half of them cross sectional echocardiographic measuremen t of the isthmic region failed. The correlation coefficient for aortic diameters measured by MRI and angiography was 0.97 and that between M RI and echocardiography was 0.89. Peak velocities in the descending ao rta correlated better with residual narrowing of the aortic isthmus or distal aortic arch or both than systolic blood pressure gradients bet ween the upper and lower limbs. A peak velocity of <2 m/s in the desce nding aorta during systole excluded important restenosis. Prolongation of anterograde blood flow during diastole always indicated a morpholo gical abnormality-either important restenosis or aneurysmal dilatation . Conclusions-MRI was better than cross sectional echocardiography for imaging the aortic arch after coarctation repair and measuring its di ameter. Peak velocity in the descending aorta correlated better with r esidual stenosis than did the systolic blood pressure gradient between the upper and lower limbs and this index could be used to indicate a need for MRI.