Project Summary Safe pericardial access is an essential and challenging first step for epicardial procedures such as epicardial ablation. Over 300,000 ablation procedures are performed annually in the United States alone, and 20% of patients suffering from ventricular tachycardia will need a pericardial access procedure for epicardial ablation of the heart. The current standard of care for these patients is fluoroscopically guided pericardial access. Unfortunately, tissues layers and key cardiac structures are not easily visible under fluoroscopy leading to accidental needle stick with ventricular puncture and excessive pericardial bleeding in 10% of cases. In low volume centers, complications are even more common, and cardiothoracic surgeons are on-site to perform emergency surgery if necessary. There is a clear unmet clinical need for a device to enable safe, consistent, pericardial access as an alternative to fluoroscopic guidance. The goal of this Phase I STTR project is to demonstrate superior pericardial access with resulting epicardial mapping and ablation using color imaging as compared to fluoroscopically guided procedures (standard of care). To achieve this goal, we will complete the following specific aims: Aim 1: Develop the next generation PeriScope device and demonstrate usability and compatibility with fluoro-free epicardial mapping. We will 1) reduce PeriScope’s access needle to 18G while maintaining high image resolution image quality and 2) develop a color imaging introducer to visualize ablation catheters entering the pericardial space. These innovations will enable a fluoroless pericardial access procedure which will be validated in a 24 subject usability study. Aim 2: Demonstrate improved pericardial access in an acute in vivo study. We will compare pericardial access with resulting epicardial mapping and ablation using the fluoro-free PeriScope tool to fluoroscopically guided procedures. We will compare procedure times and safety as measured by 1) number of pericardial access attempts, 2) severity of complications, 3) number of heart perforations, and 4) resulting volume of pericardial bleeding. This research could have a transformative impact in changing current clinical practice by converting a challenging fluoroscopically guided procedure to a more intuitive and safe color imaging technique. While this study focuses on pericardial access for epicardial ablation, the technique could also be used to deliver epicardial pacing and defibrillation therapies for infants and children with congenital heart disease, as well as benefit thousands of adult patients who have indications for cardiac resynchronization therapy but do not achieve successful implantation due to lack of transvenous access or adequate coronary sinus venous tributaries.