BIPLANE TRANSESOPHAGEAL ECHOCARDIOGRAPHY, TRANSTHORACIC DOPPLER, AND MAGNETIC-RESONANCE-IMAGING IN THE ASSESSMENT OF COARCTATION OF THE AORTA

This study compared flow-sensitive magnetic resonance imaging with bip lane transoesophageal echocardiography in combination with continuous wave Doppler from the suprasternal notch in patients with native coarc tation or after surgical repair. Twenty patients (mean age 33 years, r ange 17-60) were investigated, of whom 15 had under-gone surgery at me an age 13 years, range 5-43. Peak and mean flow in the ascending and d escending aorta as well as coarctation peak velocity were determined w ith the magnetic resonance imaging phase contrast technique. Coarctati on peak velocity was also measured by Doppler from the jugulum. Magnet ic resonance imaging axial sections as well as biplane transoesophagea l echocardiography were used to measure the smallest diameter of the c onstricted segment. Sixteen healthy volunteers, mean age 36 years, ran ge 22-63, provided reference values for magnetic resonance imaging det ermined volume of flow in the aorta. Peak flow in the descending aorta was 9.2 +/- 3.7 l.min(-1) (reference 13.0 +/- 2.5, P<0.01) and mean f low 3.1 +/- 0.9 l.min(-1) (reference 3.4 +/- 0.8, P>0.05). The ratio o f descending-to-ascending peak flow was 0.54 +/- 0.17 (reference 0.69 +/- 0.10, P<0.01) and mean flow 0.68 +/- 0.15 (reference 0.69 +/- 0.08 , P>0.05). The coarctation velocity was slightly higher with Doppler t han with magnetic resonance imaging (+0.24 +/- 0.44 m.s(-1), 95% confi dence interval +0.45 to +0.02 m.s(-1), P=0.05). The coarctation diamet er was slightly larger with magnetic resonance imaging than with trans oesophageal echocardiography (1.4 +/- 3.5 mm, 95% confidence interval +3.1 to -0.3 mm, P=0.11). Both methods are suitable for the assessment and follow-up of coarctation of the aorta. Flow assessment with magne tic resonance imaging provides a hitherto unavailable measure with whi ch to assess the severity of obstruction.