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. 2005 Aug 2;112(5):699-706.
doi: 10.1161/CIRCULATIONAHA.105.542647. Epub 2005 Jul 25.

Real-time magnetic resonance imaging-guided stenting of aortic coarctation with commercially available catheter devices in Swine

Amish N Raval  1 , James D Telep, Michael A Guttman, Cengizhan Ozturk, Michael Jones, Richard B Thompson, Victor J Wright, William H Schenke, Ranil DeSilva, Ronnier J Aviles, Venkatesh K Raman, Michael C Slack, Robert J Lederman
Affiliations

Real-time magnetic resonance imaging-guided stenting of aortic coarctation with commercially available catheter devices in Swine

Amish N Raval et al. Circulation. .

Abstract

Background: Real-time MR imaging (rtMRI) is now technically capable of guiding catheter-based cardiovascular interventions. Compared with x-ray, rtMRI offers superior tissue imaging in any orientation without ionizing radiation. Translation to clinical trials has awaited the availability of clinical-grade catheter devices that are both MRI visible and safe. We report a preclinical safety and feasibility study of rtMRI-guided stenting in a porcine model of aortic coarctation using only commercially available catheter devices.

Method and results: Coarctation stenting was performed wholly under rtMRI guidance in 13 swine. rtMRI permitted procedure planning, device tracking, and accurate stent deployment. "Active" guidewires, incorporating MRI antennas, improved device visualization compared with unmodified "passive" nitinol guidewires and shortened procedure time (26+/-11 versus 106+/-42 minutes; P=0.008). Follow-up catheterization and necropsy showed accurate stent deployment, durable gradient reduction, and appropriate neointimal formation. MRI immediately identified aortic rupture when oversized devices were tested.

Conclusions: This experience demonstrates preclinical safety and feasibility of rtMRI-guided aortic coarctation stenting using commercially available catheter devices. Patients may benefit from rtMRI in the future because of combined device and tissue imaging, freedom from ionizing radiation, and the ability to identify serious complications promptly.

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Figures

Figure 1
Figure 1
Surgically created aortic coarctation in swine before (A–C) and after (D, E) stenting. A, D, Black-blood DIR-FSE MRI. B, E, Contrast-enhanced MRA. C, F, Radiocontrast angiography. Stent-related shielding artifact obliterates contrast in stent lumen (E). Scalloped appearance of aortic wall from apposed stent (D).
Figure 2
Figure 2
rtMRI multislice axial (top left), sagittal (bottom left), and 3D-rendered (right) display of stent delivery across aortic coarctation. Passive (A) and active (B) guidewire tracking are compared. Dumbbell-shaped balloon carrying centrally crimped stent (white arrows) can be seen in both approaches; however, wire is much more clearly visible with active guidewire. S indicates superior; I, inferior; A, anterior; and P, posterior.
Figure 3
Figure 3
Stent delivery sequence. A, Advancing balloon/stent over active guidewire. Also see Data Supplement Movie I. B, Positioning into coarctation. Also see Data Supplement Movie II. C, Balloon inflation. D, Shielding artifact darkens aorta after balloon and guidewire are withdrawn.
Figure 4
Figure 4
Velocity map before and after stenting through plane indicated by blue line. Aortic cross sections are displayed as color maps during systole. Sample 1 shows jet acceleration from coarctation lesion; sample 2, flow reversal from turbulent blood flow; and sample 3, restoration of laminar flow with minimal blood acceleration after stenting.
Figure 5
Figure 5
Early detection of aortic perforation. A, DIR-FSE image of coarctation at before stenting. B, Contrast exit at superior edge of stent (arrow). C, DIR-FSE shows apposed oversized stent with blood accumulation along aortic wall (arrow).
Figure 6
Figure 6
Intentional aortic rupture. A, Simultaneous coronal (top left), axial (bottom left), and sagittal slices displayed and 3D rendered (right). Active wire is across coarctation (green), and oversized balloon is inflated. B, During continuous rtMRI, periaortic hematoma is evident immediately (arrows). DIR-FSE images before (C, D) and after (E, G) intentional rupture. Extravasation appears white. Abbreviations as in Figure 2. Also see Data Supplement Movie III.
Figure 7
Figure 7
Representative necropsy specimen 66 days after stent deployment. Sutures used to create coarctation are visible (arrows). Stent struts are fully apposed to wall and fully endothelialized.
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