1348781 - Cardiac Magnetic Resonance (CMR) and Magnetic Resonance Angiography (MRA) for Treatment-Resistant Hypertension in Adolescent Pregnancy

A 16-year-old G1P0 female at 32w1d was transferred to our academic hospital due to concern for premature labor. History was significant for gestational diabetes and poorly controlled hypertension, blood pressure (BP) up to 171/96 mmHg prior to transfer. Records from prior workup were not available. Echocardiogram demonstrated critical aortic coarctation measuring 3 mm with a peak gradient of 50 mmHg, bicuspid aortic valve without stenosis and severely dilated left atrium and ventricle with LVEF of 60%. Patient was mildly symptomatic with orthopnea. Delivery was planned for 37w, however patient returned to hospital just days later with systolic blood pressure (SBP) in 190s. Labor was induced with assisted second stage of delivery to minimize pushing. Delivery was uncomplicated, and the neonate’s Apgar score was 8 at 10 minutes. CMR and MRA were performed promptly after delivery, for surgical planning. Patient was discharged on labetalol 800 mg TID and nifedipine 60 mg BID.

Several months later, the patient underwent balloon dilation and placement of 14 mm x 34 mm covered CP stent. Labetalol dose was reduced to 200 mg BID and nifedipine was discontinued. Two weeks post-op, patient’s SBPs were in 120s.


Diagnostic Techniques and Their Most Important Findings:

CMR and MRA confirmed severe coarctation with near interruption of the aortic isthmus and hypoplastic aortic arch, bicuspid aortic valve without stenosis, and mild aortic regurgitation (Figure 1). LVEF was 56%, LV mass 194 g (above the 97^th percentile, which is 142 g^[1]), and LV mass index 116 g/m² (z-score 7.2).

Cardiac CTA was obtained for procedural planning (Figure 2). Extensive collateral vessels noted in the neck and along the descending thoracic aorta. Right and left subclavian arteries were dilated.

Post-procedural chest radiograph – the first radiograph performed – showed rib notching (Figure 3), classically associated with coarctation, with undefined sensitivity and specificity.^[2] Post-procedural CTA showed patent stent graft.


Learning Points from this Case:

In an adolescent with treatment-resistant hypertension, a diagnosis of late-presenting coarctation should be considered; our case demonstrates this applies also in pregnancy with gestational diabetes. Coarctation may not be detected until adolescence or adulthood, particularly in the context of extensive collateralization.^[3] Diagnostic imaging for hypertension includes echocardiography, CMR, MRA or CTA aorta and renal arteries, and renal ultrasound. CMR is an effective, non-invasive, and non-ionizing diagnostic tool to evaluate cardiac function in patients with resistant hypertension.^[4] MRA and CTA both evaluate collaterals, which can help with clinical decision making in challenging cases. MRA aorta can also be used to measure velocity and flow volumes, and to calculate pressure gradient. This case reinforces the role of CMR and MRA in the evaluation of secondary hypertension. It also demonstrates how extensive collateralization can be – sufficient to support a desired pregnancy to viability and longer.