Real-time magnetic resonance imaging–guided transcatheter aortic valve replacement

Abstract

OBJECTIVES Transcatheter aortic valve replacement (TAVR) has become a treatment option for otherwise inoperable or high risk patients. Currently TAVR is performed with a combination of fluoroscopy and transesophageal echocardiography, which has visual limitations including a two dimensional view and poor soft tissue contrast. Real-time magnetic resonance imaging (rtMRI) guidance overcomes these limitations with a three dimensional view of anatomical structures, improved soft tissue contrast, and allows pinpoint accuracy of device delivery. To date a device clinically available in the US has not been used for rtMRI TAVR. We present our results using the CoreValve® device. METHODS The Medtronic CoreValve® delivery catheter system was minimally modified by the investigators to be MRI compatible by replacing the stainless steel components with fluoroplastic resin and high density polyethylene components. Eight swine ranging between 60 and 90 kg underwent rtMRI guided TAVR with an active guidewire via a left subclavian approach. RESULTS Two imaging planes (long axis view and short axis view) were utilized simultaneously for real-time imaging during implantation. Successful deployment was performed without rapid ventricular pacing or cardiopulmonary bypass. Post-deployment images were acquired to evaluate the final valve position in addition to valvular and cardiac function. CONCLUSIONS Our results show that the CoreValve® can be easily and effectively deployed from the left subclavian approach by utilizing rtMRI guidance, a minimally modified valve delivery catheter system, and an active guidewire. This method allows superior visualization prior to deployment, thereby allowing deployment of the valve with pinpoint accuracy. rtMRI has the added benefit of the ability to perform immediate post-procedural functional assessment, while eliminating the morbidity of radiation exposure, rapid ventricular pacing, contrast media renal toxicity, and a more invasive procedure. Use of a commercially available device brings this rtMRI guided approach closer to a clinical reality.

Improved passive catheter tracking with positive contrast for CMR-guided cardiac catheterization using partial saturation (pSAT)

“…Active tracking has been used in CMR-guided electrophysiology studies [ 31 – 34 ]. However, there are no active catheters or guide-wires in clinical use for congenital/structural heart disease with only pre-clinical experience in transcatheter aortic valve implantation and mitral valve interventions [ 16 , 35 ].…”

Interventional cardiac magnetic resonance imaging: current applications, technology readiness level, and future perspectives

“… 112 , 113 After the initial proof of concept in 2004, several other in vivo animal studies have been performed. 32 – 38 It has been shown that the commercially available Medtronic CoreValve ® prosthesis can be used under real-time MR guidance, with small modifications made to the delivery device, of which the metal braiding had to be removed due to severe susceptibility artifacts. 35 , 112 , 113 …”

A guide for pre-procedural imaging for transcatheter aortic valve replacement patients

“…Herein, we have reviewed current technology for assessing the anatomy, physiology, and pathophysiology of the aortic valvular complex, ventricular function, and peripheral vasculature, including echocardiography, cardiac catheterization, cardiac computed tomography, and cardiac magnetic resonance. While large, high-volume academic centers are continually pushing the frontiers of imaging technology and capabilities (Miller et al 2016 ; Biaggi et al 2015 ), and the multimodal imaging techniques outlined in this review are sufficient for safely and effectively caring for the vast majority of patients undergoing TAVR procedures. Our hope is that this review, albeit niche, will increase the familiarity and understanding of currently used imaging technologies for all team members caring for TAVR patients.…”