Unique Protocoling for Unique Anatomy – Individualizing CMR to Evaluate Coarctation of the Aorta (QF_SA_127)

A 43 year-old female with a past medical history of post-ductal coarctation of the aorta presented for evaluation of progressive dyspnea with exertion. She had a history of coarctation of the aorta with occlusion of the aortic lumen distal to the left subclavian takeoff, repaired shortly after birth with a tube graft connecting the left subclavian artery with the proximal thoracic aorta. Her course was complicated by re-coarctation at 15 years old, requiring a second graft from the ascending aorta to the abdominal aorta. She presented now with a chief complaint of progressively worsening dyspnea on exertion. Physical exam was largely normal including a non-elevated JVP, absence of murmurs on cardiac auscultation, and palpated pulses that were symmetric without brachial-femoral delay. Blood pressure measured from each extremity was not elevated and symmetric. Transthoracic echocardiography was obtained showing normal left ventricular size without evidence of hypertrophy and low-normal ejection fraction of about 50% with a tricuspid aortic valve.


Diagnostic Techniques and Their Most Important Findings:

Cardiac MR angiography was obtained using time resolved imaging of contrast kinetics (TRICKS), a MRA technique in which an initial non-contrast full resolution image is obtained and then layered with a series of partial k-space images in parallel acquisition focused on the passage of a contrast bolus, creating a dynamic contrast-enhanced MRA image of vasculature. This showed severe coarctation of the aortic arch consistent with a Type A interrupted aortic arch with two arterial conduits. The proximal conduit was positioned anterior to the right heart and was 16 cm in length with a sharp 142 degree bend connecting the mid ascending aorta to the abdominal aorta. The second conduit was 5.3 cm long and positioned superiorly, connecting the proximal left subclavian artery to the thoracic aorta. Both conduits were found to be patent with inner conduit diameters measuring 16 mm and 12 mm respectively.  Given cardiac MR TRICKS protocoling showing unobstructed flow as well as normal left ventricular size and function seen on echocardiography, it was determined that residual or recurrent arch obstruction was not the cause of her current symptoms. Instead, she was found to be severely deconditioned stating she has been previously recommended to remain sedentary. She was recommended to engage in regular mild-to-moderate aerobic exercise with improvement in her symptoms.


Learning Points from this Case:

Adult patients with congenital heart defects can benefit from imaging with individualized protocoling to best evaluate their unique anatomy. Serial anatomic evaluation with cardiac MR may be preferred over CT-angiography to limit lifetime radiation burden. Advanced imaging with TRICKS protocoling allows for MR angiography with high spatial and temporal resolution, and is therefore an ideal non-invasive option for evaluating cases of complex vascular anatomy and flow such as aortic coarctation.