Real‐time MRI guided atrial septal puncture and balloon septostomy in swine

Abstract

Cardiac perforation during atrial septal puncture (ASP) might be avoided by improved image guidance. X-ray fluoroscopy (XRF), which guides ASP, visualizes tissue poorly and does not convey depth information. Ultrasound is limited by device shadows and constrained imaging windows. Alternatively, real-time MRI (rtMRI) provides excellent tissue contrast in any orientation and may enable ASP and balloon atrial septostomy (BAS) in swine. Custom MRI catheters incorporated "active" (receiver antenna) and "passive" (iron or gadolinium) elements. Wholly rtMRI-guided transfemoral ASP and BAS were performed in 10 swine in a 1.5T interventional suite. Hemodynamic results were measured with catheters and velocity encoded MRI. Successful ASP was performed in all 10 animals. Necropsy confirmed septostomy confined within the fossa ovalis in all. BAS was successful in 9/10 animals. Antenna failure in a re-used needle led to inadvertent vena cava tear prior to BAS in 1 animal. ASP in the same animal was easily performed using a new needle. rtMRI illustrated clear device-tissue-lumen relationships in multiple orientations, and facilitated simple ASP and BAS. The mean procedure time was 19 +/- 10 minutes. Septostomy achieved a mean left to right shunt ratio of 1.3:1 in these healthy animals. Interactive rtMRI permits rapid transcatheter ASP and BAS in swine. Further technical development may enable novel applications.

Electroanatomic Mapping and Radiofrequency Ablation of Porcine Left Atria and Atrioventricular Nodes Using Magnetic Resonance Catheter Tracking

“…Image resolution and contrast-to-noise ratio was sufficient for con- struction of all the required 2D and 3D data for navigation to/within the atrium and/or the AV node. Similar to results achieved in LV EAM, 19 the inherent signal-to-noise and acoustic advantages of MR trackingbased navigation over real-time (rapid, high-bandwidth) MR image-based navigation 18,20,[22][23][24][25] allowed the navigation and ablation procedures to be conducted with an open radiofrequency door and without any hearing protection.In the atrial procedures, 2 devices (EP catheter and torqueable sheath) and in the AV node procedures, 3 devices (EP catheter, torqueable sheath, and stimulation/ pacing catheter) were tracked simultaneously at 13 to 15 fps, at a 1.4ϫ1.4ϫ1.4 mm spatial resolution. Because the MR EP system allows for several simultaneous displays, separate windows were used to focus on individual devices, which proved important when the device positions were greatly separated.…”

Magnetic Resonance–Guided Cardiac Interventions Using Magnetic Resonance–Compatible Devices

“…In particular, animal i-MRI has been used to facilitate procedures such as creation or closure of atrial septal communications, 11,[17][18][19] intracoronary imaging as well as coronary and carotid artery interventions, 9,12,20 -24 stenting of pulmonary arteries, 25 aortic coarctation, 26,27 and vena cava interventions. 28,29 The procedures have been aided by the use of non-MR-safe active guide wires and prototype or commercially available devices and were either solely MR-guided or combined with conventional catheterization before and after the procedure.…”

Real-Time Magnetic Resonance Imaging–Guided Endovascular Recanalization of Chronic Total Arterial Occlusion in a Swine Model

“…16,19 CTO recanalization is a more complex procedure because the vascular lumen is smaller, the diseased vessels tend to be tortuous, and the risk of lethal perforation is higher when catheters are manipulated within the high-pressure arterial system. These support the principle that MRI has potential utility to guide conventional and novel catheter-based interventions because of superior tissue visualization.…”

“…Advances in rapid imaging, combined with development of catheter devices visible under MRI, have made real-time MRI (rtMRI)-guided therapeutic interventions feasible. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] We hypothesize that rtMRI can guide catheter navigation within an occluded artery and that combined CTO recanalization and percutaneous transluminal angioplasty can be conducted en-tirely under rtMRI guidance with the use of custom MRIvisible devices in a swine model.…”