Real-time MRI guided atrial septal puncture and balloon septostomy in swine
Amish N Raval1, Parag V Karmarkar, Michael A Guttman
1Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892-1538, USA.
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.
Insights
Real-time MRI (rtMRI) offers improved guidance for cardiac procedures like atrial septal puncture (ASP) and balloon atrial septostomy (BAS), potentially preventing complications in swine models.
Area of Science:
- Cardiovascular Imaging
- Interventional Cardiology
- Medical Device Development
Background:
- Cardiac perforation during atrial septal puncture (ASP) is a risk associated with current imaging guidance like X-ray fluoroscopy (XRF) and ultrasound.
- XRF offers poor tissue visualization and lacks depth information, while ultrasound has limitations due to device shadows and constrained imaging windows.
Purpose of the Study:
- To evaluate the feasibility of using real-time MRI (rtMRI) for guiding transfemoral atrial septal puncture (ASP) and balloon atrial septostomy (BAS) in a swine model.
- To assess the safety and efficacy of rtMRI-guided procedures compared to conventional methods.
Main Methods:
- Ten swine underwent transcatheter ASP and BAS guided by rtMRI in a 1.5T interventional suite.
- Custom MRI catheters with active and passive elements were utilized.
- Hemodynamic measurements were obtained using catheters and velocity-encoded MRI.
Main Results:
- Successful ASP was achieved in all 10 swine, with necropsy confirming septostomy within the fossa ovalis.
- Successful BAS was achieved in 9 out of 10 animals.
- rtMRI provided clear visualization of device-tissue-lumen relationships, facilitating the procedures. Mean procedure time was 19 ± 10 minutes.
Conclusions:
- Interactive rtMRI enables rapid and safe transcatheter ASP and BAS in swine.
- rtMRI guidance holds promise for improving safety and potentially enabling novel applications in interventional cardiology.
