June 01, 2019
Mayo Clinic is a recognized world leader in the development of innovative approaches to the science and delivery of medical care. In the last decade, there has been tremendous growth and expansion in innovative pursuits to address the unmet needs of the patient, the provider and the health care system. To facilitate those endeavors, Mayo Clinic Cardiovascular Medicine formed the Virtual Reality Innovations Group, directed by Suraj Kapa, M.D., an electrophysiologist at Mayo Clinic in Rochester, Minnesota.
Augmented and virtual reality
Augmented reality (AR) and virtual reality (VR) describe disruptive innovative technologies that have the potential to vastly change the landscape of cardiology practice and approach to patient care. VR is a completely simulated, interactive and computer-generated experience. Any type of sensory feedback can be incorporated; although most environments utilize visual and auditory feedback, medical systems frequently also incorporate tactile feedback. AR involves real-world objects and environments overlaid seamlessly with computer-generated perceptions. AR starts with the real world and alters the environment, while VR creates a totally simulated world.
VR clip from patient defibrillation system with cardiac structures stripped away
Clip from projected VR of patient cardiac device shows combined epicardial-endocardial pacing-defibrillation system with cardiac structures stripped away and projected in 3D space.
Dr. Kapa and his colleagues use Digital Imaging and Communications in Medicine (DICOM) images from computerized tomography or magnetic resonance imaging to create a virtual 3D space, which provides an immersive and engaging new way to visualize patient images. This technique provides a remarkably different perspective to both planned procedures and patient care.
In patients with complex congenital heart disease undergoing cardiac ablation or device procedures, this technology re-creates patient regional anatomy in a 3D space, appreciating subtle patient anatomical variations as well as relationships to collateral structures. It has also been successfully applied to help with pre-procedural planning in patients with implanted cardiac devices undergoing extraction. In addition, VR techniques are proving to be a valuable tool in the training of residents and fellows. Future additions to this lab will include tactile and haptic feedback, which will bring realistic touch, force feedback and precise motion tracking.
Artificial intelligence (AI) has the ability to detect and recognize patterns that elude humans, providing unique opportunities to further understand disease pathophysiology, diagnoses and treatments. AI has already shown tremendous promise, with the Food and Drug Administration approving three AI medical devices last year.
The Cardiovascular Innovation Laboratory is fully immersing itself in AI and applying AI to the many different facets of its current practice. Mayo Clinic cardiology's use of AI to detect asymptomatic left ventricular dysfunction from the surface electrocardiogram (ECG) was discussed in Mayo Clinic Cardiovascular Update in 2019, based on the team's research published in Nature Medicine in 2019.
Dr. Kapa's team is currently exploring the application of AI algorithms to the ECG in sinus rhythm to screen for occult atrial fibrillation (AF). The team used a cohort of 77,428 Mayo Clinic patients to develop and test the AI algorithm. Using the developed algorithm, the team identified an electrocardiographic signature during normal sinus rhythm that could predict with excellent accuracy an AF diagnosis (with area under the curve of 0.84, sensitivity 76.1%, specificity 76.4% and overall accuracy of 76.4%).
About 20% of patients with a stroke from AF were unaware of AF prior to the stroke diagnosis. Although the U.S. Preventive Services Task Force has concluded that there is insufficient evidence to determine whether the benefits of screening asymptomatic individuals for AF outweigh the harms, development of an innovative method to detect those patients at risk of developing AF could provide an opportunity to implement primary and secondary treatment strategies and reduce the risk of complications from AF, such as stroke.
Novel devices and procedures
Novel device creation, procedure development and testing are all specialties of Mayo Clinic's advanced cardiovascular innovation research. Examples include:
Minimally invasive pericardiectomy for treatment of heart failure with preserved ejection fraction
Half of patients with heart failure have a preserved ejection fraction (HFpEF), and unfortunately to date there are very few effective treatments available. Electrophysiologist Samuel J. Asirvatham, M.D., and heart failure specialist Barry A. Borlaug, M.D., have developed a minimally invasive pericardiectomy approach as a potential treatment option for patients with HFpEF. The hypothesis is that removal of the pericardium will lead to improved effective LV diastolic compliance (even as myocardial properties remain unchanged) because the external constraining effect of the pericardium has been eliminated.
Catheter prototype in place with blade poised for minimally invasive pericardiectomy
A fluoroscopic image pair of the catheter prototype used for the minimally invasive pericardiectomy shows, at left, the catheter in place with blade located at tip. At right, after slicing the pericardium with the device, a catheter is clearly observed outside the epicardial space.
Results to date are encouraging, demonstrating that percutaneous resection of the pericardium, performed in a minimally invasive subxiphoid procedure, attenuates the rise in left ventricular filling pressures during volume loading in normal dogs and in a hypertensive pig model with features of human HFpEF.
In addition to reduced filling pressures, improvements in left ventricular volume with saline loading also were observed. Drs. Asirvatham and Borlaug have received a Mayo Clinic Transform the Practice Award for this project, and a patient pilot is planned.
Carbon nanotube patches to facilitate cardiac conduction
Current treatment approaches for ventricular arrhythmias (VA) focus on anti-arrhythmic medications or cardiac ablation to achieve tissue homogenization or to physically disrupt regions of slowly conducting myocardium. Although more patients are being treated with ablative approaches, sometimes ablation is not feasible, leaving the patient with limited alternatives.
A team led by Dr. Kapa is studying the application of a biopatch with mechanical, electrical and physiological properties consistent with native cardiac tissue to these areas of slow conduction. To produce the biopatch, the team created a nanofibrillated cellulose single-walled carbon nanotube bioink and used it to 3D-print desired conductive patterns. The end product is a carbon nanotube biopatch that is flexible, mechanically robust and, most importantly, highly conductive, allowing propagation of conduction between two different zones of normal cardiac tissue but bypassing the disrupted zone.
Restoration of cardiac activation with a carbon nanotube biopatch
Three phases of restoration of cardiac activation with a carbon nanotube biopatch are shown in three rows of images. Starting at top left, this row shows that after obtaining a baseline, surgical disruption of myocardium was performed. In the middle level, after disruption, there is a clear change in the activation wavefront as indicated by isochronal activation pattern. At the bottom level, upon application of the conductive carbon nanotube biopatch, there was restoration of activation pattern back to baseline.
The biopatches were tested on canines in vivo, where a thoracotomy was performed to expose the ventricular surface and an incision was made in the myocardium to create a surgical disruption. With passive application of the biopatch, restoration of the cardiac electrical wavefront activation pattern returned to baseline (pre-surgical incision). This study truly demonstrates a potential novel approach to arrhythmia therapy.
Researchers across the entire Mayo Clinic enterprise continue to explore the application of these pioneering technologies to advance the science and improve patient care.
For more information
Cardiovascular Innovation Laboratory. Mayo Clinic.
Mayo Clinic. Artificial Intelligence-enabled ECG screening for asymptomatic left ventricular dysfunction. Cardiovascular Update. 2019;17(1).
Attia ZI, et al. Screening for cardiac contractile dysfunction using an artificial intelligence–enabled electrocardiogram. Nature Medicine. 2019;25:70.