Magnetic resonance imaging of a distorted left subclavian artery course: an important clue to an unusual type of double aortic arch.

The objective of this study was to determine if distortion of the left subclavian artery course distinguishes double aortic arch with atretic left dorsal aorta from right aortic arch with mirror image branching. We performed a retrospective case series at a tertiary care center. Twenty-six patients undergoing magnetic resonance imaging for suspicion of a vascular ring were identified, 6 of whom had an atretic left dorsal aorta confirmed by surgical inspection. Six patients with the diagnosis of right aortic arch with mirror image branching were identified for comparison. The course of the left subclavian artery was assessed using surface-rendered magnetic resonance angiography (MRA) and axial fast spin echo images. All patients with double aortic arch had clinical symptoms suggestive of esophageal or tracheal compression. Six patients had double aortic arch, 3 of whom had an atretic left dorsal aorta. In these 3 patients, the branching patterns on MRA mimicked right aortic arch mirror image branching except for the distortion of the initial course of the left subclavian artery. Surgical observation confirmed the presence of an atretic left dorsal aorta that resulted in tension on the left subclavian artery pulling it posteriorly and inferiorly and completing the vascular ring. Patients with right aortic arch mirror image branching demonstrated no such subclavian artery distortion, and these patients did not have clinical symptoms suggestive of a vascular ring. Our results demonstrate that left subclavian artery distortion due to traction by an atretic left arch is an important diagnostic finding in the evaluation 6 patients with suspected vascular rings.

Coronary artery dilatation and aortic outflow tract enlargement in children with unicommissural aortic valves.

We evaluated the aortic outflow tract (AOT) and coronary artery dimensions in pediatric patients with unicommissural aortic valves. A retrospective review of an echocardiographic database identified 37 patients with unicommissural aortic valves. A total of 115 echocardiograms were reviewed, and the right coronary artery (RCA), left main coronary artery (LM), left anterior descending coronary artery aortic valve annulus, aortic root, sinotubular junction (STJ), and ascending aorta were measured and z scores determined. The aortic stenosis peak gradient and the amount of aortic regurgitation (AR) were also measured. The RCA diameter (z score, 1.85 +/- 1.8, p = 0.03) and LM diameter (z score, 1.74 +/- 1.47, p = 0.04) are significantly dilated, as are all the AOT measurements: aortic annulus (2.02 +/- 1.9, p = 0.02), aortic root (2.25 +/- 1.9, p = 0.02), STJ (2.22 +/- 1.74, p = 0.01), and ascending aorta (4.38 +/- 2.03, p < 0.001). Longitudinal follow-up showed that there was no significant variation over time in any variable. The AOT measurements were significantly correlated with each other. A trend was found in which an increasing amount of AR gave an increase in AOT measurements. The aortic gradient was not significantly associated with any measurement. Our study population demonstrated significant dilatation of the RCA and LM as well as the AOT. The dilatation of the AOT structures is likely caused by the same mechanism that accounts for the AOT dilatation in patients with bicommissural aortic valves. Dilatation of the coronary arteries may represent an intrinsic abnormality in the vessel wall. Further studies are needed to define possible changes.

Risk factors for neo-aortic root enlargement and aortic regurgitation following arterial switch operation.

The objectives of this study were to evaluate changes in dimension of the neo-aortic annulus, aortic root, and aortic anastomosis following arterial switch operation (ASO) and to identify risk factors for developing abnormal neo-aortic root enlargement and aortic regurgitation (AR). Prior studies report development of neo-aortic root dilatation and AR in a small subset of patients after ASO. Predisposing factors for neo-aortic root dilatation and development of moderate/severe AR are poorly understood. We performed a retrospective review of all patients with d-transposition of the great arteries (d-TGA) or double-outlet right ventricle with subpulmonary ventricular septal defect (VSD) who underwent ASO from May 1986 to January 2001. Serial echocardiograms were reviewed to measure neo-aortic annulus, root, and anastomosis diameter (z scores) and to determine progression of AR. Potential risk factors were assessed for developing neo-aortic root enlargement and AR. There were 119 patients (44 female and 75 male): 73 patients had simple d-TGA, 36 had d-TGA with ventricular septal defect, and 10 had a Taussig-Bing heart. The median duration of follow-up was 65 months (range, 12-180). The median neo-aortic root (z = 0.55+/-2.2; p < 0.01) and aortic annulus dimensions (z = 1.57+/-1.75; p < 0.01) were significantly increased over the study period. Aortic anastomosis diameter correlated with growth of the ascending aorta (z = 0.55+/-1.24). Development of severe neo-aortic root enlargement was associated with prior pulmonary artery (PA) banding (p < 0.01), the presence of a VSD (p = 0.03), and Taussig-Bing anatomy (p < 0.01) but was independent of coronary arterial anatomy, coronary arterial transfer technique, or associated lesions (p > 0.05). At latest follow-up, there was no or trivial AR in 88 patients, mild AR in 29 patients, and moderate to severe AR in 3 patients. Risk factors for developing mild or worse AR included severe or rapid neo-aortic root dilatation (p < 0.01). Only 3 patients required surgical intervention for AR. Despite the significant prevalence of neo-aortic root enlargement at intermediate follow-up after ASO, there is a low incidence of significant AR. Prior PA banding, the presence of VSD, and Taussig-Bing anatomy are risk factors for severe root enlargement. Surgical intervention for AR was rare (2%), however, serial surveillance of such patients is vital to monitor for neo-aortic root enlargement and potential aortic valve dysfunction.